Internal Revenue Bulletin 2025-41 (PDF rendition): IRS Revenue Rulings

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Bulletin No. 2025–41
October 6, 2025
HIGHLIGHTS
OF THIS ISSUE
These synopses are intended only as aids to the reader in
identifying the subject matter covered. They may not be
relied upon as authoritative interpretations.
ADMINISTRATIVE, INCOME TAX
Notice 2025-54, page 479.
Optional special per diem rates. This notice provides the
2025-2026 special per diem rates for taxpayers to use in
substantiating the amount of ordinary and necessary business
expenses incurred while traveling away from home. The notice
includes (1) the special transportation industry rate, (2) the
rate for the incidental expenses only deduction, and (3) the
rates and list of high-cost localities for the high-low substanti-
ation method.
EXCISE TAX
Notice 2025-51, page 448.
This Notice of Determinations adds 39 chemical substances
to the list of taxable substances under § 4672 subject to the
tax imposed by § 4671.
INCOME TAX
Notice 2025-52, page 474.
This notice explains the circumstances under which the four-
year replacement period under section 1033(e)(2) is extended
for livestock sold on account of drought. The Appendix to this
notice contains a list of counties that experienced exceptional,
extreme, or severe drought conditions during the 12-month
period ending August 31, 2025. Taxpayers may use this list to
determine if any extension is available.
Rev. Rul. 2025-19, page 445.
Federal rates; adjusted federal rates; adjusted federal long-
term rate, and the long-term tax exempt rate. For purposes of
sections 382, 1274, 1288, 7872 and other sections of the
Code, tables set forth the rates for October 2025.
Rev. Rul. 2025-20, page 447.
Fringe benefits aircraft valuation formula. For purposes of sec-
tion 1.61-21(g) of the Income Tax Regulations, relating to the
rule for valuing non-commercial flights on employer-provided
aircraft, the Standard Industry Fare Level (SIFL) cents-per-mile
rates and terminal charge in effect for the second half of 2025
are set forth.
Finding Lists begin on page ii.

The IRS Mission
Provide America’s taxpayers top-quality service by helping
them understand and meet their tax responsibilities and
enforce the law with integrity and fairness to all.
Introduction
The Internal Revenue Bulletin is the authoritative instrument
of the Commissioner of Internal Revenue for announcing offi-
cial rulings and procedures of the Internal Revenue Service
and for publishing Treasury Decisions, Executive Orders, Tax
Conventions, legislation, court decisions, and other items of
general interest. It is published weekly.
It is the policy of the Service to publish in the Bulletin all sub-
stantive rulings necessary to promote a uniform application
of the tax laws, including all rulings that supersede, revoke,
modify, or amend any of those previously published in the
Bulletin. All published rulings apply retroactively unless other-
wise indicated. Procedures relating solely to matters of inter-
nal management are not published; however, statements of
internal practices and procedures that affect the rights and
duties of taxpayers are published.
Revenue rulings represent the conclusions of the Service
on the application of the law to the pivotal facts stated in
the revenue ruling. In those based on positions taken in rul-
ings to taxpayers or technical advice to Service field offices,
identifying details and information of a confidential nature are
deleted to prevent unwarranted invasions of privacy and to
comply with statutory requirements.
Rulings and procedures reported in the Bulletin do not have the
force and effect of Treasury Department Regulations, but they
may be used as precedents. Unpublished rulings will not be
relied on, used, or cited as precedents by Service personnel in
the disposition of other cases. In applying published rulings and
procedures, the effect of subsequent legislation, regulations,
court decisions, rulings, and procedures must be considered,
and Service personnel and others concerned are cautioned
against reaching the same conclusions in other cases unless
the facts and circumstances are substantially the same.
The Bulletin is divided into four parts as follows:
Part I.—1986 Code.
This part includes rulings and decisions based on provisions
of the Internal Revenue Code of 1986.
Part II.—Treaties and Tax Legislation.
This part is divided into two subparts as follows: Subpart A,
Tax Conventions and Other Related Items, and Subpart B,
Legislation and Related Committee Reports.
Part III.—Administrative, Procedural, and Miscellaneous.
To the extent practicable, pertinent cross references to these
subjects are contained in the other Parts and Subparts. Also
included in this part are Bank Secrecy Act Administrative
Rulings. Bank Secrecy Act Administrative Rulings are issued
by the Department of the Treasury’s Office of the Assistant
Secretary (Enforcement).
Part IV.—Items of General Interest.
This part includes notices of proposed rulemakings, disbar-
ment and suspension lists, and announcements.
The last Bulletin for each month includes a cumulative index
for the matters published during the preceding months. These
monthly indexes are cumulated on a semiannual basis, and are
published in the last Bulletin of each semiannual period.
The contents of this publication are not copyrighted and may be reprinted freely. A citation of the Internal Revenue Bulletin as the source would be appropriate.
October 6, 2025 Bulletin No. 2025–41

Part I
Section 1274.—
Determination of Issue
Price in the Case of Certain
Debt Instruments Issued for
Property
(Also Sections 42, 280G, 382, 467, 468, 482, 483,
1288, 7520, 7872.)
Rev. Rul. 2025-19
This revenue ruling provides vari-
ous prescribed rates for federal income
tax purposes for October 2025 (the
current month). Table 1 contains the
short-term, mid-term, and long-term
applicable federal rates (AFR) for the
current month for purposes of section
1274(d) of the Internal Revenue Code.
Table 2 contains the short-term, mid-
term, and long-term adjusted applica-
ble federal rates (adjusted AFR) for the
current month for purposes of section
1288(b). Table 3 sets forth the adjusted
federal long-term rate and the long-
term tax-exempt rate described in sec-
tion 382(f). Table 4 contains the appro-
priate percentages for determining the
low-income housing credit described in
section 42(b)(1) for buildings placed in
service during the current month. How-
ever, under section 42(b)(2), the appli-
cable percentage for non-federally sub-
sidized new buildings placed in service
after July 30, 2008, shall not be less
than 9%. Finally, Table 5 contains the
federal rate for determining the present
value of an annuity, an interest for life
or for a term of years, or a remainder or
a reversionary interest for purposes of
section 7520.
REV. RUL. 2025-19 TABLE 1
Applicable Federal Rates (AFR) for October 2025
Period for Compounding
AnnualSemiannualQuarterlyMonthly
Short-term
AFR3.81%3.77%3.75%3.74%
110% AFR4.19%4.15%4.13%4.11%
120% AFR4.57%4.52%4.49%4.48%
130% AFR4.96%4.90%4.87%4.85%
Mid-term
AFR3.87%3.83%3.81%3.80%
110% AFR4.25%4.21%4.19%4.17%
120% AFR4.65%4.60%4.57%4.56%
130% AFR5.04%4.98%4.95%4.93%
150% AFR5.83%5.75%5.71%5.68%
175% AFR6.81%6.70%6.64%6.61%
Long-term
AFR4.73%4.68%4.65%4.64%
110% AFR5.22%5.15%5.12%5.10%
120% AFR5.70%5.62%5.58%5.56%
130% AFR6.17%6.08%6.03%6.00%
REV. RUL. 2025-19 TABLE 2
Adjusted AFR for October 2025
Period for Compounding
AnnualSemiannualQuarterlyMonthly
Short-term adjusted AFR2.88%2.86%2.85%2.84%
Mid-term adjusted AFR2.93%2.91%2.90%2.89%
Long-term adjusted AFR3.58%3.55%3.53%3.52%
Bulletin No. 2025–41 445 October 6, 2025

REV. RUL. 2025-19 TABLE 3
Rates Under Section 382 for October 2025
Adjusted federal long-term rate for the current month3.58%
Long-term tax-exempt rate for ownership changes during the current month (the highest of the adjusted federal
long-term rates for the current month and the prior two months.)
3.65%
REV. RUL. 2025-19 TABLE 4
Appropriate Percentages Under Section 42(b)(1) for October 2025
Note: Under section 42(b)(2), the applicable percentage for non-federally subsidized new buildings placed in service after
July 30, 2008, shall not be less than 9%.
Appropriate percentage for the 70% present value low-income housing credit8.00%
Appropriate percentage for the 30% present value low-income housing credit 3.43%
REV. RUL. 2025-19 TABLE 5
Rate Under Section 7520 for October 2025
Applicable federal rate for determining the present value of an annuity, an interest for life or a term of years,
or a remainder or reversionary interest
4.6%

Section 42.—Low-Income
Housing Credit
The applicable federal short-term, mid-term,
and long-term rates are set forth for the month of
October 2025. See Rev. Rul. 2025-19, page 445.
Section 280G.—Golden
Parachute Payments
The applicable federal short-term, mid-term,
and long-term rates are set forth for the month of
October 2025. See Rev. Rul. 2025-19 page 445.
Section 382.—Limitation
on Net Operating Loss
Carryforwards and
Certain Built-In Losses
Following Ownership
Change
The adjusted applicable federal long-term rate
is set forth for the month of October 2025. See Rev.
Rul. 2025-19, page 445.
Section 467.—Certain
Payments for the Use of
Property or Services
The applicable federal short-term, mid-term,
and long-term rates are set forth for the month of
October 2025. See Rev. Rul. 2025-19, page 445.
Section 468.—Special
Rules for Mining and Solid
Waste Reclamation and
Closing Costs
The applicable federal short-term rates are set
forth for the month of October 2025. See Rev. Rul.
2025-19, page 445.
Section 482.—Allocation
of Income and Deductions
Among Taxpayers
The applicable federal short-term, mid-term,
and long-term rates are set forth for the month of
October 2025. See Rev. Rul. 2025-19, page 445.
Section 483.—Interest on
Certain Deferred Payments
The applicable federal short-term, mid-term,
and long-term rates are set forth for the month of
October 2025. See Rev. Rul. 2025-19, page 445.
Section 1288.—Treatment
of Original Issue Discount
on Tax-Exempt Obligations
The adjusted applicable federal short-term, mid-
term, and long-term rates are set forth for the month
of October 2025. See Rev. Rul. 2025-19, page 445.
Section 7520.—Valuation
Tables
The applicable federal mid-term rates are set
forth for the month of October 2025. See Rev. Rul.
2025-19, page 445.
Section 7872.—Treatment
of Loans With Below-
Market Interest Rates
The applicable federal short-term, mid-term,
and long-term rates are set forth for the month of
October 2025. See Rev. Rul. 2025-19, page 445.

October 6, 2025 446 Bulletin No. 2025–41

Bulletin No. 2025–41 447 October 6, 2025
Section 61. Gross Income
Defined
26 CFR 1.61-21: Taxation of Fringe Benefits
Rev. Rul. 2025-20
For purposes of the taxation of fringe
benefits under section 61 of the Internal
Revenue Code, section 1.61-21(g) of
the Income Tax Regulations provides a
rule for valuing noncommercial flights
on employer-provided aircraft. Section
1.61-21(g)(5) provides an aircraft val-
uation formula to determine the value
of such flights. The value of a flight is
determined under the base aircraft valua-
tion formula (also known as the Standard
Industry Fare Level formula or SIFL)
by multiplying the SIFL cents-per-mile
rates applicable for the period during
which the flight was taken by the appro-
priate aircraft multiple provided in sec-
tion 1.61-21(g)(7) and then adding the
applicable terminal charge. The SIFL
cents-per-mile rates in the formula and
the terminal charge are calculated by the
Department of Transportation (DOT) and
are reviewed semi-annually.
The following chart sets forth the ter-
minal charge and SIFL mileage rates:
Period During Which the Flight Is Taken Terminal Charge SIFL Mileage Rates
7/1/25 - 12/31/25 $53.62 Up to 500 miles
= $.2933 per mile
501-1500 miles
= $.2237 per mile
Over 1500 miles
= $.2150 per mile
DRAFTING INFORMATION
The principal author of this revenue rul-
ing is Kathleen Edmondson of the Office
of Associate Chief Counsel (Employee
Benefits, Exempt Organizations and
Employment Taxes). For further informa-
tion regarding this revenue ruling, contact
Ms. Edmondson at (202) 317-6798 (not a
toll-free number).

October 6, 2025 448 Bulletin No. 2025–41
Part III
Superfund Tax on Chemical
Substances; Notice of
Determinations to Add
Substances to List of
Taxable Substances
Notice 2025-51
SUMMARY: This notice of determi-
nations modifies the list of taxable sub-
stances to include the following 39 sub-
stances: acrylonitrile-butadiene rubber
((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44, m=25.54),
bromo-isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80),
chloroprene rubber, ethylene-propyl-
ene-ethylidene norbornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46,
o=2.71), ethylene vinyl acetate (VA < 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05),
ethylene vinyl acetate (VA ≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58), hydro-
genated acrylonitrile-butadiene rubber
((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m= 38.86),
isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90), poly(ethylene-pro-
pylene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04,
n=40.96), emulsion styrene-butadiene rub-
ber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83, n=2.53),
solution styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16, n=32.85), emulsion
styrene butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26), solution styrene-bu-
tadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31,
n=2.50), hydrogenated acrylonitrile-buta-
diene rubber ((C
4
H
8
)
x
-(C
3
H
3
N)
y
-(C
15
H
24
O)
a
; x=2,783.05, y=1,907.27, a=5.74), bro-
mobutyl isobutylene isoprene rubber
((C
4
H
8
)
x
(C
5
H
8
)
y
(Br
2
)
z
; x=7071, y=59,
z=50), chlorobutyl isobutylene isoprene
rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Cl
2
)
z
); x=7036,
y=88, z=70), DIPE–di-isopropyl ether,
di-isodecyl phthalate, di-isononyl adipate,
di-isononyl phthalate, di-tridecyl phthalate,
ethylene propylene diene (EPDM) rubber
((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250,
z=98), isodecyl alcohol, isodecyl benzoate,
isooctyl alcohol, linear nonyl phthalate, lin-
ear nonyl undecyl phthalate, linear undecyl
phthalate, linear nonyl tri-mellitate, neo
decanoic acid, neo pentanoic acid, non-
ene, regular butyl rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036, y=88), tridecyl alcohol, tri-
isononyl tri-mellitate, di-isobutylene, poly-
isobutylene, styrene-acrylonitrile ((C
3
H
3
N)
a
-(C
8
H
8
)
s
; a=0.26, s=0.74), and acryloni-
trile butadiene styrene ((C
3
H
3
N)
a
-(C
4
H
6
)
b
-(C
8
H
8
)
s
; a=0.16, b=0.10, s=0.74),
EFFECTIVE DATES: The effective date
for purposes of the tax under section 4671
of the Internal Revenue Code (Code) for
the taxable substances added to the list is
January 1, 2026. For the effective date for
purposes of refund claims under section
4662(e) of the Code for the taxable sub-
stances added to the list, see the determi-
nation for each substance.
FOR FURTHER INFORMATION
CONTACT: Andrew Clark or Jacob
Peeples at (202) 317-6855 (not a toll-free
number).
SUPPLEMENTARY INFORMATION:
Background
Section 4671(a) of the Code imposes
an excise tax on the sale or use of a taxable
substance by the importer thereof (section
4671 tax). Section 4672(a)(1) of the Code
defines the term taxable substance as any
substance which, at the time of sale or use
by the importer, is listed as a taxable sub-
stance by the Secretary of the Treasury or
the Secretary’s delegate (Secretary) on the
list of taxable substances under section
4672(a) (List).
Under section 4672(a)(2), an importer
or exporter of any substance may request
that the Secretary determine whether such
substance should be added to the List as
a taxable substance or should be removed
from the List. Under section 4672(a)(2)
(B) and (a)(4) and (b)(2), the Secretary
is required to add a substance to the List
if the Secretary determines that any tax-
able chemicals that are listed in section
4661(b) of the Code constitute more than
20 percent of the weight, or more than
20 percent of the value, of the materials
used to produce such substance, which
determination is required under section
4672(a)(2)(B) and (a)(4) to be made based
on the predominant method of production
(weight or value test). Section 4672(a)(4)
authorizes the Secretary to remove a sub-
stance from the List only if such substance
meets neither the weight nor the value test
of section 4672(a)(2)(B).
Section 4672(a)(3) includes an initial
list of taxable substances. Section 4 of
Notice 2021-66 (2021-52 I.R.B. 901) pro-
vides the list of 101 substances that the
Secretary added to the List before Novem-
ber 15, 2021. On May 31, 2024, the Secre-
tary published a Notice of Determination
in the Federal Register (89 FR 47238)
adding polyoxymethylene to the List;
this Notice of Determination was also
published in the Internal Revenue Bul-
letin as Notice 2024-50 (2024-26 I.R.B.
1789). On August 4, 2025, the Secretary
published a Notice of Determinations in
the Federal Register (90 FR 36520) add-
ing 21 substances to the List; this Notice
of Determinations was also published in
the Internal Revenue Bulletin as Notice
2025-41 (2025-34 I.R.B. 325). Rev. Proc.
2022-26 (2022-29 I.R.B. 90), as modified
by Rev. Proc. 2023-20 (2023-15 I.R.B.
636), provides the exclusive procedures
by which an importer, exporter, or inter-
ested person may request a determination
that a particular substance be added to or
removed from the List.
Section 4671(b)(3) authorizes the Secre-
tary to prescribe a tax rate for taxable sub-
stances in lieu of the tax rate specified in
section 4671(b)(2). The tax rate prescribed
by the Secretary for a substance added to
the List is calculated by multiplying the
conversion factor for each taxable chemi-
cal used in the production of the substance
by the corresponding tax rate for that tax-
able chemical under section 4661(b), and
adding those results together. Conversion
factors are determined based on the pre-
dominant method of production of the sub-
stance. See sections 8 and 10.04(8) of Rev.
Proc. 2022-26. Importers are not required
to use the prescribed tax rate for a taxable
substance and may calculate their own rate
under section 4671(b)(1).
Pursuant to Section 4672(a)(4), this
notice of determinations modifies the List
to include the 39 additional taxable sub-
stances listed in the Summary of Determi-
nations section of this notice, as explained

Bulletin No. 2025–41 449 October 6, 2025
in the Requests to Add Substances to the
List and General Explanation of Determi-
nations sections of this notice. The deter-
mination for each specific substance added
to the List is explained in parts 1 through
39 of the Modifications to the List of Tax-
able Substances section of this notice.
The updated List and prescribed
tax rates for taxable substances will be
included in the instructions to Form 6627,
Environmental Taxes.
Summary of Determinations
On September 15, 2025, the Secretary
determined to add the following sub-
stances to the List:
1. Acrylonitrile-butadiene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44, m=25.54)
2. Bromo-isobutene-isoprene rubber
((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20,
m=1.80)
3. Chloroprene rubber
4. Ethylene-propylene-ethylidene nor-
bornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46, o=2.71)
5. Ethylene vinyl acetate (VA < 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95,
m=21.05)
6. Ethylene vinyl acetate (VA ≥ 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42,
m=24.58)
7. Hydrogenated acrylonitrile-butadiene
rubber ((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28,
m= 38.86)
8. Isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90)
9. Poly(ethylene-propylene) rubber
((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04, n=40.96)
10. Emulsion styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83, n=2.53)
11. Solution styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16, n=32.85)
12. Emulsion styrene butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26)
13. Solution styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50)
14. Hydrogenated acrylonitrile-butadiene
rubber ((C
4
H
8
)
x
-(C
3
H
3
N)
y
-(C
15
H
24
O)
a
;
x=2,783.05, y=1,907.27, a=5.74)
15. Bromobutyl isobutylene isoprene
rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Br
2
)
z
; x=7071,
y=59, z=50)
16. Chlorobutyl isobutylene isoprene rub-
ber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Cl
2
)
z
); x=7036,
y=88, z=70)
17. DIPE–di-isopropyl ether
18. Di-isodecyl phthalate
19. Di-isononyl adipate
20. Di-isononyl phthalate
21. Di-tridecyl phthalate
22. Ethylene propylene diene (EPDM)
rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
;
x=5134, y=2250, z=98)
23. Isodecyl alcohol
24. Isodecyl benzoate
25. Isooctyl alcohol
26. Linear nonyl phthalate
27. Linear nonyl undecyl phthalate
28. Linear undecyl phthalate
29. Linear nonyl tri-mellitate
30. Neo decanoic acid
31. Neo pentanoic acid
32. Nonene
33. Regular butyl rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
;
x=7036, y=88)
34. Tridecyl alcohol
35. Tri-isononyl tri-mellitate
36. Di-isobutylene
37. Polyisobutylene
38. Styrene-acrylonitrile ((C
3
H
3
N)
a
-(C
8
H
8
)
s
; a=0.26, s=0.74)
39. Acrylonitrile butadiene styrene
((C
3
H
3
N)
a
-(C
4
H
6
)
b
-(C
8
H
8
)
s
; a=0.16,
b=0.10, s=0.74)
Requests to Add Substances to the List
For each of the substances listed in
the Summary of Determinations section
of this notice, an importer or an exporter
submitted a petition to the IRS in accor-
dance with Rev. Proc. 2022-26 requesting
a determination under section 4672(a)(2)
to add the substance to the List. For each
substance, the petition represented that
taxable chemicals constitute more than 20
percent of the weight of materials used to
produce the substance, based on the pre-
dominant method of production.
General Explanation of Determinations
After reviewing the petitions for each
of the substances listed in the Summary of
Determinations section of this notice, the
Secretary determined that taxable chem-
icals constitute more than 20 percent by
weight of the materials used to produce
the substance, based on the predominant
method of production. Therefore, each
of the substances is added to the List as
required under section 4672(a)(2) and (4).
The Secretary made the determinations to
add these substances to the List in accor-
dance with the requirements of section
4672(a)(2) and (4), and pursuant to the
procedures set forth in Rev. Proc. 2022-
26, as modified by Rev. Proc. 2023-20.
The relevant information for each tax-
able substance is provided in the specific
determinations included in parts 1 through
39 of the Modifications to the List of Tax-
able Substances section of this notice.
The tax rate for each taxable substance, as
prescribed by the Secretary, is provided in
paragraph (a)(6) of each specific determi-
nation. All scientific information provided
in the specific determinations reflects
the information provided by petitioners
as published in each taxable substance’s
respective Notice of Filing.
Classification numbers proposed by
each petitioner are included in paragraph
(b) of each part, after each specific deter-
mination. The classification numbers
provided with respect to a taxable sub-
stance are not part of the determination
of whether it is added to the List and do
not impact whether such substance is a
taxable substance. Taxpayers may not rely
on classification numbers for any purpose
under sections 4661, 4662, 4671, and
4672, including (but not limited to) iden-
tification of a substance as a taxable sub-
stance on the List. Classification numbers
may change over time. The Department of
the Treasury (Treasury Department) and
the IRS do not anticipate updating this
document to reflect any such changes.
For purposes of the section 4671 tax,
all the modifications in parts 1 through 39
of the Modifications to the List of Tax-
able Substances section of this notice are
effective on and after January 1, 2026. For
purposes of refund claims under section
4662(e), see the effective date for each
specific determination in paragraph (a)(5)
(ii) of each of parts 1 through 39 of the
Modifications to the List of Taxable Sub-
stances section of this notice.
Modifications to the List of Taxable
Substances
1. Determination to Add Acrylonitrile-
butadiene Rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
;
n=13.44, m=25.54) to the List
Arlanxeo USA LLC and Arlanxeo Can-
ada Inc., importers and exporters of acrylo-

October 6, 2025 450 Bulletin No. 2025–41
nitrile-butadiene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
;
n=13.44, m=25.54), submitted a petition in
accordance with Rev. Proc. 2022-26 request-
ing to add acrylonitrile-butadiene rubber
((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44, m=25.54) to
the List. According to the petition, the tax-
able chemicals butadiene, propylene, and
ammonia constitute 64.59 percent by weight
of the materials used to produce acryloni-
trile-butadiene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
;
n=13.44, m=25.54), based on the predomi-
nant method of production.
(a) Determination. Acrylonitrile-buta-
diene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44,
m=25.54) is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
acrylonitrile-butadiene rubber is through
a radical polymerization of acrylonitrile
and butadiene in an emulsion process.
Acrylonitrile monomer is produced by the
SOHIO process (i.e., catalytic ammoxida-
tion of propylene).
(2) Stoichiometric material consump-
tion equation:
n C
4
H
6
(butadiene) + m [C
3
H
6
(propyl-
ene) + NH
3
(ammonia) + 3/2 O
2
] →
(C
4
H
6
)
n
-(C
3
H
3
N)
m
(acrylonitrile-buta-
diene rubber) + 3m H
2
O
(3) Reasons for the determination: The
acrylonitrile-butadiene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44, m=25.54) petition
was filed on February 7, 2025. The notice
of filing summarizing the petition and
requesting comments was published in the
Federal Register (90 FR 14684) on April
3, 2025. The Treasury Department and
the IRS received no written comments in
response to the notice of filing. A public
hearing was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals butadiene, pro-
pylene, and ammonia constitute more than
20 percent by weight of the materials used
in the production of acrylonitrile-butadi-
ene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44,
m=25.54), based on the predominant
method of production. Therefore, the test
in section 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of acrylo-
nitrile-butadiene rubber ((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44, m=25.54) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.58 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of acrylonitrile-butadiene rubber
((C
4
H
6
)
n
-(C
3
H
3
N)
m
; n=13.44, m=25.54)
are 0.35 for butadiene, 0.52 for propylene,
and 0.21 for ammonia. The tax rate is cal-
culated by adding the products of the con-
version factor for each taxable chemical
by the tax rate for that taxable chemical:
((0.35 x $9.74) + (0.52 x $9.74) + (0.21 x
$5.28) = $9.58).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.59.0000
(ii) Schedule B number: 4002.59.0000
(iii) CAS number: 9003-18-3
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
2. Determination to Add Bromo-
isobutene-isoprene Rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80) to the
List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters of
bromo-isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80), sub-
mitted a petition in accordance with Rev.
Proc. 2022-26 requesting to add bro-
mo-isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80) to
the List. According to the petition, the
taxable chemicals butylene, bromine,
and sodium hydroxide constitute 97.89
percent by weight of the materials used
to produce bromo-isobutene-isoprene
rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20,
m=1.80), based on the predominant
method of production.
(a) Determination. Bromo-isobu-
tene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
bromo-isobutene-isoprene rubber involves
reacting a hexane solution of butyl rubber
with elemental bromine. Butyl rubber is
produced via the cationic copolymeriza-
tion of butylene with isoprene in the pres-
ence of a Friedel-Crafts catalyst at low
temperature, around -100°C.
(2) Stoichiometric material consump-
tion equation:
n C
4
H
8
(butylene) + m C
5
H
8
(iso-
prene) + m/2 Br
2
(bromine) + m/2
NaOH (sodium hydroxide) → (C
4
H
8
)
n
(C
5
H
7.5
Br
0.5
)
m
(bromo-isobutene-iso-
prene rubber) + m/2 NaBr + m/2 H
2
O
(3) Reasons for the determination: The
bromo-isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80) peti-
tion was filed on February 7, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 14694) on
April 3, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process in
section 4672(a)(2)(B) in making this deter-
mination. A review of the stoichiometric
material consumption equation and other
information in the petition shows that the
taxable chemicals butylene, bromine, and
sodium hydroxide constitute more than
20 percent by weight of the materials
used in the production of bromo-isobu-
tene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80), based on the predom-
inant method of production. Therefore, the
test in section 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of bro-
mo-isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20, m=1.80) to
the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026

Bulletin No. 2025–41 451 October 6, 2025
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): April 1, 2023
(6) Tax rate prescribed by the Secre-
tary: $9.72 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of bromo-isobutene-isoprene
rubber ((C
4
H
8
)
n
-(C
5
H
7.5
Br
0.5
)
m
; n=98.20,
m=1.80) are 0.97 for butylene, 0.03 for
bromine, and 0.01 for sodium hydroxide.
The tax rate is calculated by adding the
products of the conversion factor for each
taxable chemical by the tax rate for that
taxable chemical: ((0.97 x $9.74) + (0.03
x $8.90) + (0.01 x $0.56) = $9.72).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.39.0000
(ii) Schedule B number: 4002.39.0000
(iii) CAS number: 68441-14-5
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
3. Determination to Add Chloroprene
Rubber to the List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters of
chloroprene rubber, submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add chloroprene rubber to
the List. According to the petition, the tax-
able chemicals butadiene, chlorine, and
sodium hydroxide constitute 100 percent
by weight of the materials used to produce
chloroprene rubber, based on the predom-
inant method of production.
(a) Determination. Chloroprene rubber
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing
chloroprene rubber is through polymeriza-
tion of chloroprene initiated by a radical
initiator in an emulsion process. Chloro-
prene monomer is made from butadiene
by first reacting it with chlorine in the gas
phase at ca 500 K to form 3,4-dichloro-
but-1-ene and 1,4-dichlorobut-2-ene. The
former, on reaction with sodium hydrox-
ide, yields chloroprene monomer.
(2) Stoichiometric material consump-
tion equation:
n [C
4
H
6
(butadiene) + Cl
2
(chlorine)
+ NaOH (sodium hydroxide)] →
(C
4
H
5
Cl)
n
(chloroprene rubber) + n
NaCl + n H
2
O
(3) Reasons for the determination:
The chloroprene rubber petition was filed
on February 7, 2025. The notice of filing
summarizing the petition and requesting
comments was published in the Federal
Register (90 FR 14691) on April 3, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals butadi-
ene, chlorine, and sodium hydroxide con-
stitute more than 20 percent by weight of
the materials used in the production of
chloroprene rubber, based on the pre-
dominant method of production. There-
fore, the test in section 4672(a)(2)(B) is
satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of chlo-
roprene rubber to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secretary:
$10.51 per ton. The conversion factors for
the taxable chemicals used in the production
of chloroprene rubber are 0.61 for butadi-
ene, 0.80 for chlorine, and 0.45 for sodium
hydroxide. The tax rate is calculated by
adding the products of the conversion fac-
tor for each taxable chemical by the tax rate
for that taxable chemical: ((0.61 x $9.74) +
(0.80 x $5.40) + (0.45 x $0.56) = $10.51).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.49.0000
(ii) Schedule B number: 4002.49.0000
(iii) CAS number: 9010-98-4
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 4002.99.0000
(ii) Schedule B number: 4002.99.0000
4. Determination to Add Ethylene-
propylene-ethylidene Norbornene
Rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
;
m=56.82, n=40.46, o=2.71) to the List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters
of ethylene-propylene-ethylidene nor-
bornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46, o=2.71), submitted
a petition in accordance with Rev. Proc.
2022-26 requesting to add ethylene-propyl-
ene-ethylidene norbornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46,
o=2.71) to the List. According to the peti-
tion, the taxable chemicals ethylene, pro-
pylene, and butadiene constitute 95.05
percent by weight of the materials used
to produce ethylene-propylene-ethylidene
norbornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46, o=2.71), based on the
predominant method of production.
(a) Determination. Ethylene-propyl-
ene-ethylidene norbornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46,
o=2.71) is added to the list of taxable sub-
stances under section 4672(a). Other per-
tinent information is as follows:
(1) Predominant method of production:
The predominant method of producing eth-
ylene-propylene-ethylidene norbornene
rubber is through the catalytic polymer-
ization of ethylene, propylene, and non-
conjugated diene monomers in a solution
using various catalysts. Non-conjugated
diene monomers include ethylidene nor-
bornene and dicyclopentadiene. The non-
conjugated diene monomers are produced
from cyclopentadiene and butadiene, and
cyclopentadiene, respectively.
(2) Stoichiometric material consump-
tion equation:
m C
2
H
4
(ethylene) + n C
3
H
6
(pro-
pylene) + o [C
5
H
6
(cyclopentadi-
ene) + C
4
H
6
(butadiene)] → (C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
(ethylene-propyl-
ene-ethylidene norbornene rubber)

October 6, 2025 452 Bulletin No. 2025–41
(3) Reasons for the determination:
The ethylene-propylene-ethylidene nor-
bornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46, o=2.71) petition
was filed on February 7, 2025. The notice
of filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 14695) on
April 3, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals ethylene, pro-
pylene, and butadiene constitute more
than 20 percent by weight of the materials
used in the production of ethylene-propyl-
ene-ethylidene norbornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46,
o=2.71), based on the predominant
method of production. Therefore, the test
in section 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
ethylene-propylene-ethylidene nor-
bornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46, o=2.71) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): April 1, 2023
(6) Tax rate prescribed by the Secretary:
$9.25 per ton. The conversion factors for
the taxable chemicals used in the produc-
tion of ethylene-propylene-ethylidene nor-
bornene rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
(C
9
H
12
)
o
; m=56.82, n=40.46, o=2.71) are 0.44 for
ethylene, 0.47 for propylene, and 0.04 for
butadiene. The tax rate is calculated by
adding the products of the conversion fac-
tor for each taxable chemical by the tax rate
for that taxable chemical: ((0.44 x $9.74) +
(0.47 x $9.74) + (0.04 x $9.74) = $9.25).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.70.0000
(ii) Schedule B number: 4002.70.0000
(iii) CAS number: 25038-36-2
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
5. Determination to Add Ethylene
Vinyl Acetate (VA < 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05) to the
List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters
of ethylene vinyl acetate (VA < 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05),
submitted a petition in accordance with
Rev. Proc. 2022-26 requesting to add eth-
ylene vinyl acetate (VA < 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05) to the
List. According to the petition, the tax-
able chemicals ethylene and methane
constitute 66.23 percent by weight of the
materials used to produce ethylene vinyl
acetate (VA < 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
;
n=78.95, m=21.05), based on the predom-
inant method of production.
(a) Determination. Ethylene vinyl
acetate (VA < 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
;
n=78.95, m=21.05) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing ethylene vinyl acetate (VA < 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05)
is through a solution polymerization
employing the monomers of ethylene and
vinyl acetate in tert-butanol as a solvent
and a radical polymerization initiator.
(2) Stoichiometric material consump-
tion equation:
n C
2
H
4
(ethylene) + m [C
2
H
4
(eth-
ylene) + 1/2 CH
4
(methane) + 2 CO +
1/2 O
2
] → (C
2
H
4
)
n
(C
4
H
6
O
2
)
m
(ethylene
vinyl acetate (VA < 50%)) + 1/2m CO
2
(3) Reasons for the determination: The
ethylene vinyl acetate (VA < 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05) peti-
tion was filed on February 7, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 14688) on
April 3, 2025. The Treasury Department
and the IRS received no written comments
in response to the notice of filing. A public
hearing was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals eth-
ylene and methane constitute more than
20 percent by weight of the materials
used in the production of, based on the
predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of eth-
ylene vinyl acetate (VA < 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95, m=21.05) to the
List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.09 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of ethylene vinyl acetate ((VA
< 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=78.95,
m=21.05) are 0.70 for ethylene and 0.04
for methane. The tax rate is calculated by
adding the products of the conversion fac-
tor for each taxable chemical by the tax
rate for that taxable chemical: ((0.70 x
$9.74) + (0.04 x $6.88) = $7.09).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 3901.30.6000
(ii) Schedule B number: 3901.30.6000
(iii) CAS number: 24937-78-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
6. Determination to Add Ethylene
Vinyl Acetate (VA ≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58) to the
List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters

Bulletin No. 2025–41 453 October 6, 2025
of ethylene vinyl acetate (VA ≥ 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58),
submitted a petition in accordance with
Rev. Proc. 2022-26 requesting to add eth-
ylene vinyl acetate (VA ≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58) to the
List. According to the petition, the tax-
able chemicals ethylene and methane
constitute 62.91 percent by weight of the
materials used to produce ethylene vinyl
acetate (VA ≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
;
n=75.42, m=24.58), based on the predom-
inant method of production.
(a) Determination. Ethylene vinyl
acetate (VA ≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
;
n=75.42, m=24.58) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing ethylene vinyl acetate (VA ≥ 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58)
is through a solution polymerization
employing the monomers of ethylene and
vinyl acetate in tert-butanol as a solvent
and a radical polymerization initiator.
(2) Stoichiometric material consump-
tion equation:
n C
2
H
4
(ethylene) + m [C
2
H
4
(eth-
ylene) + 1/2 CH
4
(methane) + 2 CO +
1/2 O
2
] → (C
2
H
4
)
n
(C
4
H
6
O
2
)
m
(ethylene
vinyl acetate (VA ≥ 50%)) + 1/2m CO
2
(3) Reasons for the determination:
The ethylene vinyl acetate (VA ≥ 50%)
((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58)
petition was filed on February 7, 2025.
The notice of filing summarizing the
petition and requesting comments was
published in the Federal Register (90
FR 14683) on April 3, 2025. The Trea-
sury Department and the IRS received
no written comments in response to the
notice of filing. A public hearing was nei-
ther requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals ethylene and
methane constitute more than 20 percent
by weight of the materials used in the
production of, based on the predominant
method of production. Therefore, the test
in section 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of eth-
ylene vinyl acetate (VA ≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42, m=24.58) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $6.77 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of ethylene vinyl acetate (VA
≥ 50%) ((C
2
H
4
)
n
-(C
4
H
6
O
2
)
m
; n=75.42,
m=24.58) are 0.66 for ethylene and 0.05
for methane. The tax rate is calculated by
adding the products of the conversion fac-
tor for each taxable chemical by the tax
rate for that taxable chemical: ((0.66 x
$9.74) + (0.05 x $6.88) = $6.77).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 3905.29.0000
(ii) Schedule B number: 3905.29.0000
(iii) CAS number: 24937-78-8
(2) The Secretary is unable to confirm
the following classification numbers: Not
applicable.
7. Determination to Add Hydrogenated
Acrylonitrile-Butadiene Rubber
((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m=38.86)
to the List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters
of hydrogenated acrylonitrile-butadi-
ene rubber ((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28,
m=38.86), submitted a petition in
accordance with Rev. Proc. 2022-26
requesting to add hydrogenated acry-
lonitrile-butadiene rubber ((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m=38.86) to the
List. According to the petition, the
taxable chemicals butadiene, propyl-
ene, ammonia, and methane constitute
63.48 percent by weight of the materials
used to produce hydrogenated acryloni-
trile-butadiene rubber ((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m=38.86), based on the pre-
dominant method of production.
(a) Determination. Hydrogenated
acrylonitrile-butadiene rubber ((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m=38.86) is added
to the list of taxable substances under sec-
tion 4672(a). Other pertinent information
is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing hydrogenated acrylonitrile-butadiene
rubber is via catalytic hydrogenation of
acrylonitrile-butadiene rubber which is
derived from the emulsion polymerization
of butadiene and acrylonitrile.
(2) Stoichiometric material consump-
tion equation:
n C
4
H
6
(butadiene) + m [C
3
H
6
(pro-
pylene) + NH
3
(ammonia) + 3/2 O
2
]
+ n [1/4 CH
4
(methane) + 1/2 H
2
O]
→ (C
4
H
8
)
n
-(C
3
H
3
N)
m
(hydrogenated
acrylonitrile-butadiene rubber) + 3m
H
2
O + 1/4n CO
2
(3) Reasons for the determination:
The hydrogenated acrylonitrile-butadi-
ene rubber (C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28,
m=38.86) petition was filed on February
7, 2025. The notice of filing summariz-
ing the petition and requesting comments
was published in the Federal Register (90
FR 14686) on April 3, 2025. The Trea-
sury Department and the IRS received
two non-substantive written comments in
response to the notice of filing. One com-
ment received by the IRS recommended
prohibiting the manufacture of this sub-
stance. The other comment received by
the IRS was unrelated to the determina-
tion for this substance. The comments
did not address whether hydrogenated
acrylonitrile-butadiene rubber ((C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m=38.86) meets
the weight or value test under section
4672(a)(2)(B). A public hearing was nei-
ther requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals butadiene, pro-
pylene, ammonia, and methane constitute
more than 20 percent by weight of the
materials used in the production of, based
on the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.

October 6, 2025 454 Bulletin No. 2025–41
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
hydrogenated acrylonitrile-butadiene
rubber (C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28,
m=38.86) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Sec-
retary: $9.54 per ton. The conversion
factors for the taxable chemicals used
in the production of hydrogenated
acrylonitrile-butadiene rubber (C
4
H
8
)
n
-(C
3
H
3
N)
m
; n=22.28, m=38.86) are 0.36
for butadiene, 0.49 for propylene, 0.20
for ammonia, and 0.03 for methane.
The tax rate is calculated by adding the
products of the conversion factor for
each taxable chemical by the tax rate for
that taxable chemical: ((0.36 x $9.74) +
(0.49 x $9.74) + (0.20 x $5.28) + (0.03 x
$6.88) = $9.54).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.59.0000
(ii) Schedule B number: 4002.59.0000
(iii) CAS number: 308068-83-9
(2) The Secretary is unable to confirm
the following classification numbers: Not
applicable.
8. Determination To Add Isobutene-
isoprene Rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
;
n=99.10, m=0.90) to the List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters of
isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90) submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add isobutene-isoprene rub-
ber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90)
to the List. According to the petition, the
taxable chemical butylene constitutes
98.91 percent by weight of the materials
used to produce isobutene-isoprene rub-
ber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90),
based on the predominant method of pro-
duction.
(a) Determination. Isobutene-iso-
prene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10,
m=0.90) is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of pro-
ducing isobutene-isoprene rubber is via
the cationic copolymerization of butylene
with isoprene in the presence of a Frie-
del-Crafts catalyst at low temperature,
around -100°C. The final product contains
0.7 wt% of additives.
(2) Stoichiometric material consump-
tion equation:
n C
4
H
8
(butylene) + m C
5
H
8
(isoprene)
→ (C
4
H
8
)
n
(C
5
H
8
)
m
(isobutene-isoprene
rubber)
(3) Reasons for the determination:
The isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90) petition
was filed on February 7, 2025. The notice
of filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 14689) on
April 3, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process in
section 4672(a)(2)(B) in making this deter-
mination. A review of the stoichiometric
material consumption equation and other
information in the petition shows that the
taxable chemical butylene constitutes more
than 20 percent by weight of the materials
used in the production of isobutene-iso-
prene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10,
m=0.90), based on the predominant method
of production. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of isobu-
tene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
;
n=99.10, m=0.90) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.64 per ton. The conversion factor
for the butylene used in the production of
isobutene-isoprene rubber ((C
4
H
8
)
n
-(C
5
H
8
)
m
; n=99.10, m=0.90) is 0.99. The tax rate
is calculated by multiplying the conver-
sion factor by the tax rate for butylene:
(0.99 x $9.74 = $9.64).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.31.0000
(ii) Schedule B number: 4002.31.0000
(iii) CAS number: 9010-85-9
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
9. Determination to Add Poly(ethylene-
propylene) Rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
;
m=59.04, n=40.96) to the List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters of
poly(ethylene-propylene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04, n=40.96), submit-
ted a petition in accordance with Rev.
Proc. 2022-26 requesting to add poly(eth-
ylene-propylene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
;
m=59.04, n=40.96) to the List. According
to the petition, the taxable chemicals eth-
ylene and propylene constitute 100 percent
by weight of the materials used to produce
poly(ethylene-propylene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04, n=40.96), based on
the predominant method of production.
(a) Determination. Poly(ethylene-pro-
pylene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
;
m=59.04, n=40.96) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of pro-
ducing poly(ethylene-propylene) rubber
is through the catalytic polymerization
of ethylene and propylene monomers in a
solution using various catalysts.
(2) Stoichiometric material consump-
tion equation:
m C
2
H
4
(ethylene) + n C
3
H
6
(propyl-
ene) → (C
2
H
4
)
m
-(C
3
H
6
)
n
(poly(eth-
ylene-propylene) rubber)
(3) Reasons for the determination: The
poly(ethylene-propylene) rubber ((C
2
H
4
)

Bulletin No. 2025–41 455 October 6, 2025
m
-(C
3
H
6
)
n
; m=59.04, n=40.96) petition
was filed on February 7, 2025. The notice
of filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 14690) on
April 3, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals ethylene and
propylene constitute more than 20 percent
by weight of the materials used in the pro-
duction of poly(ethylene-propylene) rub-
ber ((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04, n=40.96),
based on the predominant method of
production. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
poly(ethylene-propylene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04, n=40.96) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Sec-
retary: $9.74 per ton. The conversion
factors for the taxable chemicals used in
the production of poly(ethylene-propyl-
ene) rubber ((C
2
H
4
)
m
-(C
3
H
6
)
n
; m=59.04,
n=40.96) are 0.49 for ethylene and 0.51
for propylene. The tax rate is calculated
by adding the products of the conver-
sion factor for each taxable chemical
and the tax rate for that taxable chem-
ical: ((0.49 x $9.74) + (0.51 x $9.74) =
$9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 9010-71-1
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 3901.40.0000
(ii) Schedule B number: 3901.40.0000
10. Determination to Add Emulsion
Styrene-butadiene Rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83, n=2.53) to the List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters
of emulsion styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83; n=2.53), sub-
mitted a petition in accordance with Rev.
Proc. 2022-26 requesting to add emulsion
styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83; n=2.53) to the List. Accord-
ing to the petition, the taxable chemicals
butadiene, benzene, and ethylene consti-
tute 100 percent by weight of the materials
used to produce emulsion styrene-butadi-
ene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83;
n=2.53), based on the predominant
method of production.
(a) Determination. Emulsion sty-
rene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
;
m=15.83; n=2.53) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing emulsion styrene-butadiene rubber is
through the emulsion polymerization of
butadiene and styrene initiated by free
radicals. Styrene monomer is produced by
the dehydrogenation of ethylbenzene. Eth-
ylbenzene is produced via a Friedel-Crafts
reaction of benzene and ethylene.
(2) Stoichiometric material consump-
tion equation:
m C
4
H
6
(butadiene) + n [C
6
H
6
(ben-
zene) + C
2
H
4
(ethylene)] → (C
4
H
6
)
m
-(C
8
H
8
)
n
(emulsion styrene-butadiene
rubber) + n H
2
(hydrogen)
(3) Reasons for the determination:
The emulsion styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83; n=2.53) peti-
tion was filed on February 7, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 14686) on
April 3, 2025. The Treasury Department
and the IRS received no written comments
in response to the notice of filing. A public
hearing was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals buta-
diene, benzene, and ethylene constitute
more than 20 percent by weight of the
materials used in the production of emul-
sion styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83; n=2.53), based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of emul-
sion styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83; n=2.53) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.74 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of emulsion styrene-butadi-
ene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=15.83;
n=2.53) are 0.76 for butadiene, 0.18 for
benzene, and 0.06 for ethylene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.76 x $9.74) + (0.18 x $9.74)
+ (0.06 x $9.74) = $9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS numbers: 4002.19.0015
(rubber), 4002.11.0000 (latex)
(ii) Schedule B numbers: 4002.19.9000
(rubber), 4002.11.0000 (latex)
(iii) CAS number: 9003-55-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
11. Determination to Add Solution
Styrene-butadiene Rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16, n=32.85) to the
List
Arlanxeo USA LLC and Arlanxeo
Canada Inc., importers and exporters of
solution styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16; n=32.85), submitted
a petition in accordance with Rev. Proc.

October 6, 2025 456 Bulletin No. 2025–41
2022-26 requesting to add solution sty-
rene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
;
m=67.16; n=32.85) to the List. Accord-
ing to the petition, the taxable chemicals
butadiene, benzene, and ethylene consti-
tute 100 percent by weight of the materi-
als used to produce solution styrene-buta-
diene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16;
n=32.85), based on the predominant
method of production.
(a) Determination. Solution sty-
rene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
;
m=67.16; n=32.85) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of pro-
duction: The predominant method of
producing solution styrene-butadiene
rubber is through the anionic polym-
erization of butadiene and styrene ini-
tiated by alkyl lithium compounds in
hexanes as solvent. Styrene monomer
is produced by the dehydrogenation of
ethylbenzene. Ethylbenzene is produced
via a Friedel-Crafts reaction of benzene
and ethylene.
(2) Stoichiometric material consump-
tion equation:
m C
4
H
6
(butadiene) + n [C
6
H
6
(ben-
zene) + C
2
H
4
(ethylene)] → (C
4
H
6
)
m
-(C
8
H
8
)
n
(solution styrene-butadiene
rubber) + n H
2
(hydrogen); m=67.16;
n=32.85
(3) Reasons for the determination:
The solution styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16; n=32.85)
petition was filed on February 7, 2025.
The notice of filing summarizing the
petition and requesting comments was
published in the Federal Register (90
FR 14690) on April 3, 2025. The Trea-
sury Department and the IRS received
no written comments in response to the
notice of filing. A public hearing was nei-
ther requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals butadiene, ben-
zene, and ethylene constitute more than 20
percent by weight of the materials used in
the production of solution styrene-buta-
diene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16;
n=32.85), based on the predominant
method of production. Therefore, the test
in section 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of solu-
tion styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16; n=32.85) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.74 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of solution styrene-butadiene rub-
ber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=67.16; n=32.85)
are 0.51 for butadiene, 0.36 for benzene,
and 0.13 for ethylene. The tax rate is cal-
culated by adding the products of the con-
version factor for each taxable chemical
and the tax rate for that taxable chemical:
((0.51 x $9.74) + (0.36 x $9.74) + (0.13 x
$9.74) = $9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 9003-55-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 4002.19.0016
(ii) Schedule B number: 4002.19.1600
12. Determination to Add Emulsion
Styrene Butadiene Rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26) to the List
Michelin North America, Inc., an
importer of emulsion styrene butadi-
ene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14,
n=2.26), submitted a petition in accor-
dance with Rev. Proc. 2022-26 request-
ing to add emulsion styrene butadiene
rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14,
n=2.26) to the List. According to the
petition, the taxable chemicals butadiene,
benzene, and ethylene constitute 100 per-
cent by weight of the materials used to
produce emulsion styrene butadiene rub-
ber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26),
based on the predominant method of pro-
duction.
(a) Determination. Emulsion sty-
rene butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
;
m=14.14, n=2.26) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
emulsion styrene butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26) is through a
low temperature, emulsion copolymer-
ization of butadiene and styrene, using
fatty and rosin acid soaps as an emulsifier,
and organic hydroperoxides as an initia-
tor. Styrene monomer is produced by the
dehydrogenation of ethylbenzene. Ethyl-
benzene is produced via a Friedel-Crafts
reaction of benzene and ethylene.
(2) Stoichiometric material consump-
tion equation:
m C
4
H
6
(butadiene) + n [C
6
H
6
(ben-
zene) + C
2
H
4
(ethylene)] → (C
4
H
6
)
m
-(C
8
H
8
)
n
(emulsion styrene butadiene
rubber) + n H
2
(hydrogen); m=14.14;
n=2.26
(3) Reasons for the determination:
The emulsion styrene butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26) peti-
tion was filed on February 7, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 14692) on
April 3, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals buta-
diene, benzene, and ethylene constitute
more than 20 percent by weight of the
materials used in the production of emul-
sion styrene butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26), based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of emul-
sion styrene butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14, n=2.26) to the List:

Bulletin No. 2025–41 457 October 6, 2025
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.74 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of emulsion styrene butadi-
ene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=14.14,
n=2.26) are 0.76 for butadiene, 0.18 for
benzene, and 0.06 for ethylene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.76 x $9.74) + (0.18 x $9.74)
+ (0.06 x $9.74) = $9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.19.0015
(ii) Schedule B number: 4002.19.9000
(iii) CAS number: 9003-55-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
13. Determination to Add Solution
Styrene-butadiene Rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50) to the List
Michelin North America, Inc., an
importer of solution styrene-butadi-
ene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31,
n=2.50), submitted a petition in accor-
dance with Rev. Proc. 2022-26 requesting
to add solution styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50) to
the List. According to the petition, the
taxable chemicals butadiene, benzene and
ethylene constitute 100 percent by weight
of the materials used to produce solution
styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50), based on the pre-
dominant method of production.
(a) Determination. Solution sty-
rene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
;
m=13.31, n=2.50) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
solution styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50) is through
the continuous polymerization of butadi-
ene and styrene initiated by alkyl lithium
compounds in toluene or CMHC (cyclo-
hexane and methylhexane) as solvents.
Styrene monomer is produced by the
dehydrogenation of ethylbenzene. Ethyl-
benzene is produced via a Friedel-Crafts
reaction of benzene and ethylene.
(2) Stoichiometric material consump-
tion equation:
m C
4
H
6
(butadiene) + n [C
6
H
6
(ben-
zene) + C
2
H
4
(ethylene)] → (C
4
H
6
)
m
-(C
8
H
8
)
n
(solution styrene butadiene
rubber) + n H
2
(hydrogen); m=13.31;
n=2.5
(3) Reasons for the determination:
The solution styrene-butadiene rubber
((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50) peti-
tion was filed on February 7, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 14693) on
April 3, 2025. The Treasury Department
and the IRS received one non-substantive
written comment on the necessity of the
filing to understand its impact in response
to the notice of filing. The comment did
not address whether solution styrene-buta-
diene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31,
n=2.50) meets the weight or value test
under section 4672(a)(2)(B). A public
hearing was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals buta-
diene, benzene and ethylene constitute
more than 20 percent by weight of the
materials used in the production of solu-
tion styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50), based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of solu-
tion styrene-butadiene rubber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026

(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.74 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of solution styrene-butadiene rub-
ber ((C
4
H
6
)
m
-(C
8
H
8
)
n
; m=13.31, n=2.50)
are 0.73 for butylene, 0.20 for benzene,
and 0.07 for ethylene. The tax rate is cal-
culated by adding the products of the con-
version factor for each taxable chemical
and the tax rate for that taxable chemical:
((0.73 x $9.74) + (0.20 x $9.74) + (0.07 x
$9.74) = $9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.19.0016
(ii) Schedule B number: 4002.19.1600
(iii) CAS number: 9003-55-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
14. Determination to Add
Hydrogenated Acrylonitrile-butadiene
Rubber ((C
4
H
8
)
x
-(C
3
H
3
N)
y
-(C
15
H
24
O)
a
;
x=2,783.05, y=1,907.27, a=5.74) to the
List
Zeon Chemicals L.P., an importer
and exporter of hydrogenated acryloni-
trile-butadiene rubber ((C
4
H
8
)
x
-(C
3
H
3
N)
y
-(C
15
H
24
O)
a
; x=2,783.05, y=1,907.27,
a=5.74), also known as “HNBR,” sub-
mitted a petition in accordance with Rev.
Proc. 2022-26 requesting to add HNBR
to the List. According to the petition, the
taxable chemicals butadiene, propylene,
ammonia, methane, butylene, toluene, sul-
furic acid, and sodium hydroxide consti-
tute 67.01 percent by weight of the mate-
rials used to produce HNBR, based on the
predominant method of production.
(a) Determination. Hydrogenated
acrylonitrile-butadiene rubber ((C
4
H
8
)
x
-(C
3
H
3
N)
y
-(C
15
H
24
O)
a
; x=2,783.05,
y=1,907.27, a=5.74) is added to the list of
taxable substances under section 4672(a).
Other pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
HNBR is via catalytic hydrogenation of

October 6, 2025 458 Bulletin No. 2025–41
acrylonitrile-butadiene rubber (“NBR”)
in a solution of acetone and in the pres-
ence of a catalyst. NBR is derived from
the emulsion polymerization of butadiene
and acrylonitrile. Acrylonitrile monomer
is produced by the SOHIO process (i.e.,
catalytic ammoxidation of propylene).
Hydrogen is made from steam-methane
reforming. Butylated hydroxytoluene is
produced from the reaction of p-cresol
with butylene. p-Cresol is prepared by a
two-step route beginning with the sulfon-
ation of toluene, followed by basic hydro-
lysis.
(2) Stoichiometric material consump-
tion equation:
x C
4
H
6
(butadiene) + y C
3
H
6
(propyl-
ene) + y NH
3
(ammonia) + 3/2y O
2
+
1/2x CH
4
(methane) + x H
2
O + a C
7
H
8

(toluene) + a H
2
SO
4
(sulfuric acid) +
2a NaOH (sodium hydroxide) + 2a
C
4
H
8
(butylene) → (C
4
H
8
)
x
-(C
3
H
3
N)
y
-(C
15
H
24
O)
a
(HNBR) + 1/2x CO
2
(car-
bon dioxide)+ (3y+2a) H
2
O (water)
+ a Na
2
SO
3
(sodium sulfite)+ x H
2
1

(hydrogen)
(3) Reasons for the determination: The
HNBR petition was filed on February 14,
2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
14685) on April 3, 2025, and a correction
was published in the Federal Register (90
FR 19245) on May 6, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals butadi-
ene, propylene, ammonia, methane, buty-
lene, toluene, sulfuric acid, and sodium
hydroxide constitute more than 20 per-
cent by weight of the materials used in
the production of HNBR, based on the
predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
HNBR to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): April 1, 2023
(6) Tax rate prescribed by the Secre-
tary: $10.02 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of HNBR are 0.58 for butadi-
ene, 0.31 for propylene, 0.13 for ammo-
nia, 0.09 for methane, 0.002 for butylene,
0.002 for toluene, 0.002 for sulfuric acid,
and 0.002 for sodium hydroxide. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.58 x $9.74) + (0.31 x $9.74)
+ (0.13 x $5.28) + (0.09 x $6.88) + (0.002
x $9.74) + (0.002 x $9.74) + (0.002 x
$0.52) + (0.002 x $0.56) = $10.02).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.59.0000
2
(ii) Schedule B number: 4002.59.0000
(iii) CAS number: 88254-10-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
15. Determination to Add Bromobutyl
Isobutylene Isoprene Rubber (((C
4
H
8
)
x
(C
5
H
8
)
y
(Br
2
)
z
); x=7071, y=59, z=50) to
the List
Exxon Mobil Corporation, an exporter
of bromobutyl isobutylene isoprene rub-
ber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Br
2
)
z
; x=7071, y=59,
z=50), also known as “BIIR,” submitted
a petition in accordance with Rev. Proc.
2022-26 requesting to add BIIR to the
List. According to the petition, the tax-
able chemicals isobutylene (an isomer of
butylene) and bromine constitute 99.01
percent by weight of the materials used to
produce BIIR, based on the predominant
method of production.
(a) Determination. Bromobutyl isobu-
tylene isoprene rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Br
2
)
z
; x=7071, y=59, z=50) is added to
the list of taxable substances under section
4672(a). Other pertinent information is as
follows:
(1) Predominant method of produc-
tion: The predominant method of reg-
ular butyl rubber production is using a
carbocationic polymerization reaction
of isobutylene and a comonomer of iso-
prene. The catalyst system used is typi-
cally composed of aluminum chloride,
boron trifluoride or similar dissolved in
a methyl chloride solvent. Monomer feed
of isobutylene and isoprene dissolved
in a methyl chloride solvent are fed to a
reactor operated at approximately -100°C
to control the rapid exothermic polymer-
ization reaction generating a high molec-
ular weight butyl rubber polymer. To
obtain this high molecular weight poly-
mer it is necessary for the feed monomers
to be as pure as possible ensuring that the
feed system stays as dry as possible. The
methyl chloride and unreacted monomers
are flashed overhead and recycled back to
the feed system while the polymer is pre-
cipitated out as a solid which is finished
and packaged.
The polymerization process for BIIR
starts with the exact same process for reg-
ular butyl rubber outlined above. A subse-
quent halogenation step is then carried out
in a well agitated vessel to ionically sub-
stitute a bromine molecule to the polymer
backbone while the polymer is dissolved
in an appropriate solvent. The solvent
is then flashed precipitating out a solid
which is then baled and packaged.
(2) Stoichiometric material consump-
tion equation:
7071 C
4
H
8
(isobutylene) + 59 C
5
H
8

(isoprene) + 50 Br
2
(bromine) →
[7071 C
4
H
8
+ 59 C
5
H
8
+ 50 Br
2
]
(BIIR)
1
The petition, and consequently the notice of filing, inadvertently omitted “x H
2
” from the products side of the stoichiometric material consumption equation. This omission has no impact on
the weight or value test. For clarity “x H
2
” has been included here.
2
The Notice of Filing erroneously stated that the HTSUS number as “4002.59.000” and the Schedule B number as “4002.59.000.” These errors are corrected here.

Bulletin No. 2025–41 459 October 6, 2025
(3) Reasons for the determination:
The BIIR petition was filed on April 8,
2025.
3
The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
20346) on May 13, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals isobutylene (an
isomer of butylene) and bromine consti-
tute more than 20 percent by weight of the
materials used in the production of BIIR,
based on the predominant method of pro-
duction. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of BIIR
to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.63 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of BIIR are 0.97 for butylene
and 0.02 for bromine. The tax rate is
calculated by adding the products of the
conversion factor for each taxable chemi-
cal and the tax rate for that taxable chem-
ical: ((0.97 x $9.74) + (0.02 x $8.90) =
$9.63).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.39.00
(ii) Schedule B number: 4002.39.00
(iii) CAS number: 68441-14-5
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
16. Determination to Add Chlorobutyl
Isobutylene Isoprene Rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Cl
2
)
z
); x=7036, y=88, z=70) to
the List
Exxon Mobil Corporation, an exporter
of chlorobutyl isobutylene isoprene rub-
ber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Cl
2
)
z
); x=7036, y=88,
z=70), also known as “CIIR,” submitted
a petition in accordance with Rev. Proc.
2022-26 requesting to add CIIR to the
List. According to the petition, the taxable
chemicals isobutylene (an isomer of buty-
lene) and chlorine constitute 98.50 percent
by weight of the materials used to produce
CIIR, based on the predominant method
of production.
(a) Determination. Chlorobutyl isobu-
tylene isoprene rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
(Cl
2
)
z
); x=7036, y=88, z=70) is added to
the list of taxable substances under section
4672(a). Other pertinent information is as
follows:
(1) Predominant method of production:
The predominant method of production
of regular butyl rubber is using a carbo-
cationic polymerization reaction of isobu-
tylene and a comonomer of isoprene. The
catalyst system used is typically composed
of aluminum chloride, boron trifluoride
or similar with an initiator dissolved in a
methyl chloride solvent. Monomer feed
of isobutylene and isoprene dissolved in a
methyl chloride solvent are fed to a reac-
tor operated at approximately -100⁰C to
control the rapid exothermic polymeriza-
tion reaction generating a high molecular
weight regular butyl rubber polymer. To
obtain this high molecular weight polymer
it is necessary for the feed monomers to be
as pure as possible as well as ensuring that
the feed system stays as dry as possible.
The methyl chloride and unreacted mono-
mers are flashed overhead and recycled
back to the feed system while the polymer
is precipitated out as a solid which is then
baled and packaged.
The polymerization process for CIIR
starts with the exact same process for reg-
ular butyl rubber outlined above. A subse-
quent halogenation step is then carried out
in a well agitated vessel to ionically sub-
stitute a chlorine molecule to the polymer
backbone while the polymer is dissolved
in an appropriate solvent. The solvent
is then flashed, precipitating out a solid
which is then baled and packaged.
(2) Stoichiometric material consump-
tion equation:
7036 C
4
H
8
(isobutylene) + 88 C
5
H
8

(isoprene) + 70 Cl
2
(chlorine) → [7036
C
4
H
8
+ 88 C
5
H
8 +
70 Cl
2
] (CIIR)
(3) Reasons for the determination:
The CIIR petition was filed on April 8,
2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
20350) on May 13, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals isobu-
tylene (an isomer of butylene) and chlo-
rine constitute more than 20 percent by
weight of the materials used in the pro-
duction of CIIR, based on the predom-
inant method of production. Therefore,
the test in section 4672(a)(2)(B) is sat-
isfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of CIIR
to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.50 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of CIIR are 0.97 for butylene
and 0.01 for chlorine. The tax rate is cal-
culated by adding the products of the con-
version factor for each taxable chemical
and the tax rate for that taxable chemical:
((0.97 x $9.74) + (0.01 x $5.40) = $9.50).
3
The Notice of Filing erroneously stated the year of filing as 2023. This error is corrected here.

October 6, 2025 460 Bulletin No. 2025–41
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.39.00
(ii) Schedule B number: 4002.39.00
(iii) CAS number: 68081-82-3
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
17. Determination to Add DIPE–Di-
isopropyl Ether to the List
Exxon Mobil Corporation, an exporter
of DIPE–di-isopropyl ether submitted
a petition in accordance with Rev. Proc.
2022-26 requesting to add DIPE–di-iso-
propyl ether to the List. According to the
petition, the taxable chemical propylene
constitutes 82.40 percent by weight of the
materials used to produce DIPE–di-iso-
propyl ether, based on the predominant
method of production.
(a) Determination. DIPE–di-isopropyl
ether is added to the list of taxable sub-
stances under section 4672(a). Other per-
tinent information is as follows:
(1) Predominant method of production:
DIPE–di-isopropyl ether is produced via
isopropyl alcohol (IPA) production using
a two-step indirect hydration process.
A mixed propane/propylene stream is
reacted with aqueous sulfuric acid to form
a H
2
SO
4
/propylene extract. The formed
isopropyl hydrogen sulfate is further
reacted with additional IPA under acidic
conditions to form DIPE–di-isopropyl
ether such that two moles of isopropanol
are converted to one mole of DIPE–di-iso-
propyl ether and one mole of water.
(2) Stoichiometric material consump-
tion equation:
2 C
3
H
6
[propylene] + H
2
O [water] →
C
6
H
14
O [DIPE–di-isopropyl ether]
(3) Reasons for the determination:
The DIPE–di-isopropyl ether petition was
filed on May 1, 2025. The notice of filing
summarizing the petition and requesting
comments was published in the Federal
Register (90 FR 21126) on May 16, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemical propylene con-
stitutes more than 20 percent by weight
of the materials used in the production
of DIPE–di-isopropyl ether, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
DIPE–di-isopropyl ether to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Sec-
retary: $7.99 per ton. The conversion
factor for the propylene used in the pro-
duction of DIPE–di-isopropyl ether is
0.82. The tax rate is calculated by mul-
tiplying the conversion factor by the
tax rate for propylene: (0.82 x $9.74 =
$7.99).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 2909.19.18.00
(ii) Schedule B number: 2909.19.18.00
(iii) CAS number: 108-20-3
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
18. Determination to Add Di-isodecyl
Phthalate to the List
Exxon Mobil Corporation, an exporter
of di-isodecyl phthalate, submitted a peti-
tion in accordance with Rev. Proc. 2022-
26 requesting to add di-isodecyl phthalate
to the List. According to the petition, the
taxable chemicals propylene and orthox-
ylene (an isomer of xylene) constitute
64.50 percent by weight of the materials
used to produce di-isodecyl phthalate,
based on the predominant method of pro-
duction.
(a) Determination. Di-isodecyl phthal-
ate is added to the list of taxable sub-
stances under section 4672(a). Other per-
tinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
di-isodecyl phthalate is via esterification.
This process can be readily carried
out in heated kettles with agitation and
provision for water takeoff. Esterification
catalysts (e.g., sulfuric acid or p-toluene-
sulfonic acid) speed the reaction and are
neutralized, washed, and then removed.
The purity requirements for commercial
plasticizers are very high; phthalate esters
are usually colorless and are mostly odor-
less. In the case of phthalates, the esterifi-
cation is carried out through the reaction
of phthalic anhydride and 2-ethylhexanol
to produce dioctyl phthalate (DOP).
This reaction usually requires an
excess of alcohol, which is readily recy-
cled. Analogous syntheses yield aliphatic
dicarboxylic acid esters, benzoates, and
trimellitates.
(2) Stoichiometric material consump-
tion equation:
5.45 C
3
H
6
[propylene] + 0.35 C
5
H
10

[amylene] + 2 CO [carbon monoxide]
+ 4 H
2
[hydrogen] + C
8
H
10
[orthox-
ylene] + 3 O
2
[oxygen] → C
28
H
46
O
4

[di-isodecyl phthalate] + 4 H
2
O
[water]
(3) Reasons for the determination:
The di-isodecyl phthalate petition was
filed on April 8, 2025. The notice of filing
summarizing the petition and requesting
comments was published in the Federal
Register (90 FR 20354) on May 13, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals propylene and
orthoxylene (an isomer of xylene) consti-
tute more than 20 percent by weight of the
materials used in the production of di-iso-
decyl phthalate, based on the predominant
method of production. Therefore, the test
in section 4672(a)(2)(B) is satisfied.

Bulletin No. 2025–41 461 October 6, 2025
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
di-isodecyl phthalate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.31 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of di-isodecyl phthalate are 0.51
for propylene and 0.24 for xylene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.51 x $9.74) + (0.24 x $9.74)
= $7.31).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers: Not applicable.
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2917.33.00.10
(ii) Schedule B number: 2917.33.00.10
(iii) CAS number: 68515-49-1
19. Determination to Add Di-isononyl
Adipate to the List
Exxon Mobil Corporation, an exporter
of di-isononyl adipate, also known as
“DINA,” submitted a petition in accor-
dance with Rev. Proc. 2022-26 requesting
to add DINA to the List. According to the
petition, the taxable chemicals propylene,
benzene, and nitric acid constitute 79.20
percent by weight of the materials used to
produce DINA, based on the predominant
method of production.
(a) Determination. Di-isononyl adipate
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
DINA is produced via esterification. The
di-isononyl adipate di-ester is made by
reacting primary isononyl (C9) alcohol
with adipic acid. The ester is produced by
esterification of two moles of isononyl C9
alcohol and one mole of adipic acid in the
presence of a catalyst.
By using excess alcohol (up to 30%
molar excess of C9 alcohol) and remov-
ing the water, the equilibrium is shifted
towards the formation of the di-ester. The
reactants are charged into a reactor and
heated up. The reaction rate is acceler-
ated by using, for example, tetra-n-butyl
titanate introduced at high temperature
(140°C – 250°C), while removing the
water formed.
Excess alcohol is distilled from the
ester by vacuum prior to neutralization and
recycled into subsequent batches. The final
ester is purified by neutralizing with a base
such as an aqueous solution of sodium car-
bonate. The remaining excess water is dis-
tilled off and the ester is then filtered using
filter agents. The degree of purity of the
ester has a minimum 99.0 wt%.
(2) Stoichiometric material consump-
tion equation:
4.82 C
3
H
6
[propylene] + 0.30 C
5
H
10

[amylene] + 2 CO [carbon monoxide]
+ 7 H
2
[hydrogen] + C
6
H
6
[benzene]
+ 0.50 O
2
[oxygen] + 2 HNO
3
[nitric
acid] → C
24
H
46
O
4
[di-isononyl adi-
pate] + 4 H
2
O [water] + N
2
O [nitrous
oxide]
(3) Reasons for the determination:
The DINA petition was filed on May 1,
2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
21131) on May 16, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals propylene,
benzene, and nitric acid constitute more
than 20 percent by weight of the materi-
als used in the production of DINA, based
on the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of DINA
to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.07 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of DINA are 0.51 for propylene,
0.20 for benzene, and 0.32 for nitric acid.
The tax rate is calculated by adding the
products of the conversion factor for each
taxable chemical and the tax rate for that
taxable chemical: ((0.51 x $9.74) + (0.20
x $9.74) + (0.32 x $0.48) = $7.07).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 2917.12.20.00
(ii) Schedule B number: 2917.12.2000
(iii) CAS number: 33703–08–1
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
20. Determination to Add Di-isononyl
Phthalate to the List
Exxon Mobil Corporation, an exporter
of di-isononyl phthalate, submitted a peti-
tion in accordance with Rev. Proc. 2022-26
requesting to add di-isononyl phthalate to
the List. According to the petition, the tax-
able chemicals propylene and orthoxylene
(an isomer of xylene) constitute 62.90
percent by weight of the materials used to
produce di-isononyl phthalate, based on the
predominant method of production.
(a) Determination. Di-isononyl phthal-
ate is added to the list of taxable sub-
stances under section 4672(a). Other per-
tinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
di-isononyl phthalate is via esterification.
Most plasticizers are products of sim-
ple esterification reactions, which can be
readily carried out in heated kettles with
agitation and provision for water takeoff.
While some plants produce plasticizers

October 6, 2025 462 Bulletin No. 2025–41
by such batch methods, newer, highly
automated plants operate continuously,
particularly if they emphasize a single
product. Esterification catalysts (e.g.
sulfuric acid or p-toluenesulfonic acid)
speed the reaction and are neutralized,
washed, and then removed. The purity
requirements for commercial plasticizers
are very high; phthalate esters are usually
colorless and are mostly odorless. The
reaction usually requires an excess of
alcohol, which is readily recycled. Anal-
ogous syntheses yield aliphatic dicarbox-
ylic acid esters, benzoates, and trimelli-
tates.
The hydrogen used for these reactions
is not produced from steam-methane
reforming; the source is from a POx reac-
tor, which feeds liquids, not methane. The
POx process is an industrial process that
converts hydrocarbons feeds into syngas
(a combination of H
2
and CO gas). The
hydrocarbon feed is in the liquid state;
it does not feed gas (such as methane)
or solids. The unit feeds a variety of liq-
uid hydrocarbons such as paraffins, ole-
fins, and aromatics in the C9-C20

range,
obtained from the refinery pipestills and
other chemicals units.
(2) Stoichiometric material consump-
tion equation:
5.12 x 0.94 C
3
H
6
[propylene] + 5.12 x
0.06 C
5
H
10
[amylene] + 2 CO [carbon
monoxide] + 4 H
2
[hydrogen] + C
8
H
10

[orthoxylene] + 3 O
2
[oxygen] →
C
26
H
42
O
4
[di-isononyl phthalate] + 4
H
2
O [water]
(3) Reasons for the determination:
The di-isononyl phthalate petition
was filed on May 1, 2025. The notice
of filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 20551) on
May 14, 2025. The Treasury Depart-
ment and the IRS received no written
comments in response to the notice of
filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals propylene and
orthoxylene (an isomer of xylene) con-
stitute more than 20 percent by weight
of the materials used in the production of
di-isononyl phthalate, based on the pre-
dominant method of production. There-
fore, the test in section 4672(a)(2)(B) is
satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
di-isononyl phthalate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.11 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of di-isononyl phthalate are 0.48
for propylene and 0.25 for xylene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.48 x $9.74) + (0.25 x $9.74)
= $7.11).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers: Not applicable.
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2917.33.00.50
(ii) Schedule B number: 2917.33.00.50
(iii) CAS number: 68515-48-0
21. Determination to Add Di-tridecyl
Phthalate to the List
Exxon Mobil Corporation, an exporter
of di-tridecyl phthalate, submitted a peti-
tion in accordance with Rev. Proc. 2022-
26 requesting to add di-tridecyl phthalate
to the List. According to the petition, the
taxable chemicals propylene and orthox-
ylene (an isomer of xylene) constitute
68.10 percent by weight of the materi-
als used to produce di-tridecyl phthalate,
based on the predominant method of pro-
duction.
(a) Determination. Di-tridecyl phthal-
ate is added to the list of taxable sub-
stances under section 4672(a). Other per-
tinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
di-tridecyl phthalate
4
is via esterification.
This process can be readily carried
out in heated kettles with agitation and
provision for water takeoff. Esterifica-
tion catalysts (e.g., sulfuric acid or p-tol-
uenesulfonic acid) speed the reaction
and are neutralized, washed, and then
removed. The purity requirements for
commercial plasticizers are very high;
phthalate esters are usually colorless
and are mostly odorless. In the case of
phthalates, the esterification is carried
out through the reaction of phthalic
anhydride and 2-ethylhexanol to produce
dioctyl phthalate (DOP).
This reaction usually requires an
excess of alcohol, which is readily recy-
cled. Analogous syntheses yield aliphatic
dicarboxylic acid esters, benzoates, and
trimellitates.
(2) Stoichiometric material consump-
tion equation:
7.70 x 0.94 C
3
H
6
[propylene] + 7.70 x
0.06 C
5
H
10
[amylene] + 2 CO [carbon
monoxide] + 4 H
2
[hydrogen] + C
8
H
10

[orthoxylene] + 3 O
2
[oxygen] →
C
34
H
58
O
4
[di-tridecyl phthalate] + 4
H
2
O [water]
(3) Reasons for the determination: The
di-tridecyl phthalate petition was filed on
April 8, 2025. The notice of filing sum-
marizing the petition and requesting
comments was published in the Federal
Register (90 FR 20352) on May 13, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals pro-
4
The Notice of Filing for di-tridecyl phthalate had a typographical error misstating the name of the taxable substance in the predominant method of production section. This error is corrected
here.

Bulletin No. 2025–41 463 October 6, 2025
pylene and orthoxylene (an isomer of
xylene) constitute more than 20 percent
by weight of the materials used in the pro-
duction of di-tridecyl phthalate, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of di-tri-
decyl phthalate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.50 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of di-tridecyl phthalate are 0.57
for propylene and 0.20 for xylene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.57 x $9.74) + (0.20 x $9.74)
= $7.50).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers: Not applicable.
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2917.34.01.50
(ii) Schedule B number: 2917.34.0150
(iii) CAS number: 68515-47-9
22. Determination to Add Ethylene
Propylene Diene (EPDM) Rubber
((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134,
y=2250, z=98) to the List
Exxon Mobil Corporation, an exporter
of ethylene propylene diene (EPDM)
rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134,
y=2250, z=98), submitted a petition in
accordance with Rev. Proc. 2022-26
requesting to add EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250, z=98)
to the List. According to the petition, the
taxable chemicals ethylene, propylene,
and butadiene constitute 97.41 percent by
weight of the materials used to produce
EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
;
x=5134, y=2250, z=98), based on the pre-
dominant method of production.
(a) Determination. Ethylene propyl-
ene diene (EPDM) rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250, z=98) is added
to the list of taxable substances under sec-
tion 4672(a). Other pertinent information
is as follows:
(1) Predominant method of production:
The predominant method of producing
EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
;
x=5134, y=2250, z=98) is copolymeriza-
tion of ethylene and propylene with or
without a small amount of a non-conju-
gated diene.
(2) Stoichiometric material consump-
tion equation:
5,134 C
2
H
4
[ethylene] + 2,250 C
3
H
6

[propylene] + 98 C
4
H
6
[butadiene] +
98 C
5
H
6
[cyclopentadiene] → (5,134
C
2
H
4
+ 2,250 C
3
H
6
+ 98 C
9
H
12
)
[EPDM]
(3) Reasons for the determination:
The EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250, z=98) peti-
tion was filed on May 1, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 21825)
on May 21, 2025. The Treasury Depart-
ment and the IRS received one non-sub-
stantive written comment regarding the
effect of EPDM on the environment
and wildlife in response to the notice
of filing. The comment did not address
whether EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250, z=98) meets
the weight or value test under section
4672(a)(2)(B). A public hearing was nei-
ther requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals ethylene, pro-
pylene, and butadiene constitute more
than 20 percent by weight of the materials
used in the production of EPDM rubber
((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250,
z=98), based on the predominant method
of production. Therefore, the test in sec-
tion 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
;
x=5134, y=2250, z=98) to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.45 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of EPDM rubber ((C
2
H
4
)
x
(C
3
H
6
)
y
(C
9
H
12
)
z
; x=5134, y=2250, z=98) are 0.57
for ethylene, 0.38 for propylene, and 0.02
for butadiene. The tax rate is calculated
by adding the products of the conversion
factor for each taxable chemical and the
tax rate for that taxable chemical: ((0.57
x $9.74) + (0.38 x $9.74) + (0.02 x $9.74)
= $9.45).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.70.00
(ii) Schedule B number: 4002.70.0000
(iii) CAS number: 25034-71-3
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
23. Determination to Add Isodecyl
Alcohol to the List
Exxon Mobil Corporation, an exporter
of isodecyl alcohol, submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add isodecyl alcohol to
the List. According to the petition, the
taxable chemical propylene constitutes
72.00 percent by weight of the materials
used to produce isodecyl alcohol, based
on the predominant method of produc-
tion.
(a) Determination. Isodecyl alcohol
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing iso-
decyl alcohol is in an oxonation reaction.
Plasticizer alcohols, including isodecyl
alcohol, are derived from the oxo reaction
with branched olefins. Refinery-connected

October 6, 2025 464 Bulletin No. 2025–41
polygas units generate many of these ole-
fins as purified cuts or fractions.
The hydrogen used for these reac-
tions are not produced from steam-meth-
ane reforming. The source of hydrogen
is from a Pox reactor, which feeds liq-
uids, not methane. The Pox process is an
industrial process that converts hydrocar-
bons feeds into syngas (a combination of
hydrogen and carbon monoxide gas). The
hydrocarbon feed is in the liquid state. The
unit feeds a variety of liquid hydrocarbons
such as paraffins, olefins, and aromatics in
the C5-C20 range, obtained from the refin-
ery pipestills and other chemicals units.
(2) Stoichiometric material consump-
tion equation:
2.88 x 0.94 C
3
H
6
[propylene] + 2.88
x 0.06 C
5
H
10
[amylene] + CO [car-
bon monoxide] + 2 H
2
[hydrogen] →
C
10
H
22
O [isodecyl alcohol]
(3) Reasons for the determination: The
isodecyl alcohol petition was filed on May
1, 2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
21129) on May 16, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical propyl-
ene constitutes more than 20 percent by
weight of the materials used in the pro-
duction of isodecyl alcohol, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of iso-
decyl alcohol to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.01 per ton. The conversion factor
for the propylene used in the production
of isodecyl alcohol is 0.72. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for propylene: (0.72
x $9.74 = $7.01).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 68526-85-2
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 3823.70.60.00
(ii) Schedule B number: 3823.70.6000
24. Determination to Add Isodecyl
Benzoate to the List
Exxon Mobil Corporation, an exporter
of isodecyl benzoate, submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add isodecyl benzoate to
the List. According to the petition, the
taxable chemicals propylene and toluene
constitute 69.10 percent by weight of the
materials used to produce isodecyl benzo-
ate, based on the predominant method of
production.
(a) Determination. Isodecyl benzoate
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing
isodecyl benzoate is via esterification. The
isodecyl benzoate ester is made by react-
ing primary isodecyl (C10) alcohol with
benzoic acid. The ester is produced by
esterification of one mole of isodecyl C10
alcohol and one mole of benzoic acid in
the presence of a catalyst.
By using excess alcohol (up to 30%
molar excess of C10 alcohol) and remov-
ing the water, the equilibrium is shifted
towards the formation of the ester. The
reactants are charged into a reactor and
heated up. The reaction rate is acceler-
ated by using, for example, tetra-n-butyl
titanate introduced at high temperature
(140°C – 250°C), while removing the
water formed.
Excess alcohol is distilled from the
ester by vacuum prior to neutralization
and recycled into subsequent batches.
The final ester is purified by neutralizing
with a base such as an aqueous solution of
sodium carbonate. The remaining excess
water is distilled off and the ester is then
filtered using filter agents. The degree of
purity of the ester has a minimum 99.0
wt%.
(2) Stoichiometric material consump-
tion equation:
2.71 C
3
H
6
[propylene] + 0.17 C
5
H
10

[amylene] + CO [carbon monoxide] +
2 H
2
[hydrogen] + C
6
H
5
CH
3
[toluene]
+ 1.5 O
2
[oxygen] → C
17
H
26
O
2
[iso-
decyl benzoate] + 2 H
2
O [water]
(3) Reasons for the determination:
The isodecyl benzoate petition was
filed on May 1, 2025. The notice of
filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 21130) on
May 16, 2025. The Treasury Depart-
ment and the IRS received no written
comments in response to the notice of
filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals propylene and
toluene constitute more than 20 percent
by weight of the materials used in the pro-
duction of isodecyl benzoate, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of iso-
decyl benzoate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.60 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of isodecyl benzoate are 0.43 for
propylene and 0.35 for toluene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable

Bulletin No. 2025–41 465 October 6, 2025
chemical and the tax rate for that taxable
chemical: ((0.43 x $9.74) + (0.35 x $9.74)
= $7.60).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers: Not applicable.
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2916.31.50.00
(ii) Schedule B number: 2916.31.0002
(iii) CAS number: 131298-44-7
25. Determination to Add Isooctyl
Alcohol to the List
Exxon Mobil Corporation, an exporter
of isooctyl alcohol, submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add isooctyl alcohol to the
List. According to the petition, the tax-
able chemical propylene constitutes 68.10
percent by weight of the materials used
to produce isooctyl alcohol, based on the
predominant method of production.
(a) Determination. Isooctyl alcohol
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing isooctyl alcohol is in an oxonation
reaction. Plasticizer alcohols, including
isooctyl alcohol, are derived from the oxo
reaction with branched olefins. Refin-
ery-connected polygas units generate
many of these olefins as purified cuts or
fractions. For example, isooctyl alcohol
is produced from heptene, which is an
isomeric mixture of C7 olefins that are
derived from the reaction of propylene
and butylenes. The extent of branching
in heptane depends on the reaction con-
ditions and feedstock ratio at the polygas
units. Since these conditions are variable,
the specifications of the alcohol product
may vary among producers.
The hydrogen used for these reactions
are not produced from steam-methane
reforming. The source of hydrogen is
from POx reactor, which feeds liquids, not
methane. The POx process is an industrial
process that converts hydrocarbons feeds
into syngas (a combination of hydrogen
and carbon monoxide gas). The hydro-
carbon feed is in the liquid state. The unit
feeds a variety of liquid hydrocarbons
such as paraffins, olefins, and aromatics
in the C5-C20 range, obtained from the
refinery pipestills and other chemicals
units.
(2) Stoichiometric material consump-
tion equation:
2.24 x 0.94 C
3
H
6
[propylene] + 2.24 x
0.06 C
5
H
10
[amylene] + CO [carbon
monoxide] + 2 H
2
[hydrogen] →
C
8
H
18
O [isooctyl alcohol]
(3) Reasons for the determination:
The isooctyl alcohol petition was filed
on May 1, 2025. The notice of filing
summarizing the petition and request-
ing comments was published in the Fed-
eral Register (90 FR 21126) on May 16,
2025. The Treasury Department and the
IRS received one non-substantive writ-
ten comment regarding the importance
of evaluating the data in response to the
notice of filing. The comment did not
address whether isooctyl alcohol meets
the weight or value test under section
4672(a)(2)(B). A public hearing was nei-
ther requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical propyl-
ene constitutes more than 20 percent by
weight of the materials used in the pro-
duction of isooctyl alcohol, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
isooctyl alcohol to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $6.62 per ton. The conversion factor
for the propylene used in the production
of isooctyl alcohol is 0.68. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for propylene: (0.68
x $9.74 = $6.62).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 2905.16.00.50
(ii) Schedule B number: 2905.16.0050
(iii) CAS number: 68526-83-0
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
26. Determination to Add Linear Nonyl
Phthalate to the List
Exxon Mobil Corporation, an exporter
of linear nonyl phthalate, submitted a peti-
tion in accordance with Rev. Proc. 2022-26
requesting to add linear nonyl phthalate to
the List. According to the petition, the tax-
able chemicals ethylene and orthoxylene
(an isomer of xylene) constitute 67.40 per-
cent by weight of the materials used to pro-
duce linear nonyl phthalate, based on the
predominant method of production.
(a) Determination. Linear nonyl
phthalate is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing
linear nonyl phthalate is via esterification.
The linear nonyl phthalate di-ester is
made by reacting a mix of primary C9
alcohol with phthalic anhydride. The ester
is produced by esterification of two moles
of a linear C9 alcohol with one mole of
phthalic anhydride in the presence of an
acidic catalyst.
By using excess alcohol (up to 25%
molar excess of C9 alcohol) and remov-
ing the water, the equilibrium is shifted
towards the formation of the di-ester. The
reactants are charged into a reactor and
heated up. The reaction rate is acceler-
ated by using, for example, tetra-n-butyl
titanate introduced at high temperature
(140°C – 250°C), while removing the
water formed.
The final ester is purified by neutraliz-
ing with a base such as an aqueous solu-
tion of sodium carbonate. Then excess
alcohol is distilled off using steam/nitro-
gen stripping after neutralization. The
remaining excess water is distilled off and
the ester is then filtered using filter agents.

October 6, 2025 466 Bulletin No. 2025–41
The degree of purity of the ester is up
to > 99.5 wt%. The overall formula is
C
26
H
42
O
4
and the molecular weight is 418
g/mole, based on an average carbon num-
ber of the alkyl groups, with 9 carbons
being the predominant number.
The linear C9 alcohol is obtained
through hydroformylation of octene.
Octene is obtained through ethylene
oligomerization. Hydroformylation is the
reaction of octene, at high pressure and
temperature in the presence of a catalyst,
with syngas (a mixture of carbon mon-
oxide and hydrogen). An alcohol with
one carbon atom higher versus the start-
ing olefin is obtained, hence octene gives
nonanol. The hydroformylation induces
0.3 branches per molecule predominantly
on the 2-postion carbon of the alcohol.
phthalic anhydride is obtained through air
oxidation of o.xylene.
(2) Stoichiometric material consump-
tion equation:
8 C
2
H
4
[ethylene] + 2 CO [carbon
monoxide] + 4 H
2
[hydrogen] + C
8
H
10

[orthoxylene] + 3 O
2
[oxygen] →
C
26
H
42
O
4
[linear nonyl phthalate] + 4
H
2
O [water]
(3) Reasons for the determination:
The linear nonyl phthalate petition was
filed on April 8, 2025. The notice of filing
summarizing the petition and requesting
comments was published in the Federal
Register (90 FR 20348) on May 13, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals eth-
ylene and orthoxylene (an isomer of
xylene) constitute more than 20 percent
by weight of the materials used in the
production of linear nonyl phthalate,
based on the predominant method of
production. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of lin-
ear nonyl phthalate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.69 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of linear nonyl phthalate are 0.54
for ethylene and 0.25 for xylene. The tax
rate is calculated by adding the products
of the conversion factor for each taxable
chemical and the tax rate for that taxable
chemical: ((0.54 x $9.74) + (0.25 x $9.74)
= $7.69).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 68515-45-7
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2917.33.00.50
(ii) Schedule B number: 2917.33.0050
27. Determination to Add Linear Nonyl
Undecyl Phthalate to the List
Exxon Mobil Corporation, an exporter
of linear nonyl undecyl phthalate, sub-
mitted a petition in accordance with Rev.
Proc. 2022-26 requesting to add linear
undecyl phthalate to the List. Accord-
ing to the petition, the taxable chemicals
ethylene and orthoxylene (an isomer
of xylene) constitute 69.14 percent by
weight of the materials used to produce
linear nonyl undecyl phthalate, based on
the predominant method of production.
(a) Determination. Linear nonyl unde-
cyl phthalate is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing linear nonyl undecyl phthalate is via
esterification. The linear nonyl undecyl
phthalate di-ester is made by reacting a
mix of primary C9 alcohol and primary
C11 alcohol with phthalic anhydride. The
ester is produced by esterification of one
mole of a linear C9 alcohol and one mole
of a linear C11

alcohol mix with one mole
of phthalic anhydride in the presence of
an acidic catalyst. By using excess alco-
hol (up to 25% molar excess of the alcohol
mix) and removing the water, the equilib-
rium is shifted towards the formation of
the di-ester. The reactants are charged into
a reactor and heated up. The reaction rate
is accelerated by using, for example, tet-
ra-n-butyl titanate introduced at high tem-
perature (140°C – 250°C), while remov-
ing the water formed. The final ester is
purified by neutralizing with a base such
as an aqueous solution of sodium carbon-
ate. Then excess alcohol is distilled off
using steam/nitrogen stripping after neu-
tralization. The remaining excess water is
distilled off and the ester is then filtered
using filter agents. The degree of purity of
the ester is up to >99.5 wt%.
The overall formula is C
28
H
46
O
4
and
the molecular weight is 446 g/mole, based
on an average carbon number of the alkyl
groups, which are C9 and C11 carbons.
The linear C9/C11 alcohols are obtained
through hydroformylation of octene/
decene. octene/decene is obtained through
ethylene oligomerization. Hydroformy-
lation is the reaction of octene/decene,
at high pressure and temperature in the
presence of a catalyst, with syngas (a mix-
ture of carbon monoxide and hydrogen).
An alcohol with one carbon atom higher
versus the starting olefin is obtained,
hence octene/decene gives nonanol/unde-
canol. The hydroformylation induces 0.3
branches per molecule predominantly
on the 2-postion carbon of the alcohol.
Phthalic anhydride is obtained through air
oxidation of orthoxylene.
The hydrogen used for these reactions
is not produced from steam-methane
reforming; the source is from a POx reac-
tor, which feeds liquids, not methane. The
POx process is an industrial process that
converts hydrocarbons feeds into syngas
(a combination of hydrogen and carbon
monoxide gas). The hydrocarbon feed
is in the liquid state; it does not feed gas
(such as methane) or solids. The unit feeds
a variety of liquid hydrocarbons such as
paraffins, olefins, and aromatics in the
C5-C20

range, obtained from the refinery
pipestills and other chemicals units.
(2) Stoichiometric material consump-
tion equation:
9 C
2
H
4
[ethylene] + 2 CO [carbon
monoxide] + 4 H
2
[hydrogen] + C
8
H
10

Bulletin No. 2025–41 467 October 6, 2025
[orthoxylene] + 3 O
2
[oxygen] →
C
28
H
46
O
4
[linear nonyl undecyl phthal-
ate] + 4 H
2
O [water]
(3) Reasons for the determination:
The linear nonyl undecyl phthalate
petition was filed on April 8, 2025. The
notice of filing summarizing the petition
and requesting comments was published
in the Federal Register (90 FR 20553) on
May 14, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemicals ethylene and
orthoxylene (an isomer of xylene) con-
stitute more than 20 percent by weight
of the materials used in the production of
linear nonyl undecyl phthalate, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of lin-
ear nonyl undecyl phthalate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.89 per ton. The conversion factors
for the taxable chemicals used in the pro-
duction of linear nonyl undecyl phthalate
are 0.57 for ethylene and 0.24 for xylene.
The tax rate is calculated by adding the
products of the conversion factor for each
taxable chemical and the tax rate for that
taxable chemical: ((0.57 x $9.74) + (0.24
x $9.74) = $7.89)
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 3812.20.10.00
(ii) Schedule B number: 3812.20.0000
(iii) CAS number: 68515-43-5
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
28. Determination to Add Linear
Undecyl Phthalate to the List
Exxon Mobil Corporation, an exporter
of linear undecyl phthalate, submitted
a petition in accordance with Rev. Proc.
2022-26 requesting to add linear unde-
cyl phthalate to the List. According to the
petition, the taxable chemicals ethylene
and orthoxylene (an isomer of xylene)
constitute 70.72 percent by weight of the
materials used to produce linear unde-
cyl phthalate, based on the predominant
method of production.
(a) Determination. Linear undecyl
phthalate is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of produc-
tion: The predominant method of pro-
ducing linear undecyl phthalate di-ester
is by reacting a mix of primary C11 alco-
hol with phthalic anhydride. The ester is
produced by esterification of two moles
of a linear C11 alcohol with one mole of
phthalic anhydride in the presence of an
acidic catalyst.
By using excess alcohol (up to 25%
molar excess of C11 alcohol) and remov-
ing the water, the equilibrium is shifted
towards the formation of the di-ester. The
reactants are charged into a reactor and
heated up. The reaction rate is acceler-
ated by using, for example, tetra-n-butyl
titanate introduced at high temperature
(140°C – 250°C), while removing the
water formed.
The final ester is purified by neutraliz-
ing with a base such as an aqueous solu-
tion of sodium carbonate. Then excess
alcohol is distilled off using steam/nitro-
gen stripping after neutralization. The
remaining excess water is distilled off
and the ester is then filtered using filter
agents.
The degree of purity of the ester is
up to >99.5 wt%. The overall formula is
C
30
H
50
O
4
and the molecular weight is 474
g/mole, based on an average carbon num-
ber of the alkyl groups, with 11 carbons
being the predominant number.
The linear C11 alcohol is obtained
through hydroformylation of decene.
Decene is obtained through ethylene
oligomerization. Hydroformylation is the
reaction of decene, at high pressure and
temperature in the presence of a catalyst,
with syngas (a mixture of carbon monox-
ide and hydrogen). An alcohol with one
carbon atom higher versus the starting
olefin is obtained, hence decene gives
undecanol. The hydroformylation induces
0.3 branches per molecule predominantly
on the 2-position carbon of the alcohol.
Phthalic anhydride is obtained through air
oxidation of o.xylene.
(2) Stoichiometric material consump-
tion equation:
10 C
2
H
4
[ethylene] + 2 CO [carbon
monoxide] + 4 H
2
[hydrogen] + C
8
H
10

[orthoxylene] + 3 O
2
[oxygen] →
C
30
H
50
O
4
[linear undecyl phthalate] +
4 H
2
O [water]
(3) Reasons for the determination:
The linear undecyl phthalate petition was
filed on April 8, 2025. The notice of filing
summarizing the petition and requesting
comments was published in the Federal
Register (90 FR 20353) on May 13, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals eth-
ylene and orthoxylene (an isomer of
xylene) constitute more than 20 percent
by weight of the materials used in the
production of linear undecyl phthalate,
based on the predominant method of
production. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of lin-
ear undecyl phthalate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022

October 6, 2025 468 Bulletin No. 2025–41
(6) Tax rate prescribed by the Secre-
tary: $7.89 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of linear undecyl phthalate
are 0.59 for ethylene and 0.22 for xylene.
The tax rate is calculated by adding the
products of the conversion factor for each
taxable chemical and the tax rate for that
taxable chemical: ((0.59 x $9.74) + (0.22
x $9.74) = $7.89)
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers: Not applicable.
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2917.33.00.50
(ii) Schedule B number: 2917.33.00.50
(iii) CAS number: 3648-20-2
29. Determination to Add Linear Nonyl
Tri-mellitate to the List
Exxon Mobil Corporation, an exporter of
linear nonyl tri-mellitate, submitted a peti-
tion in accordance with Rev. Proc. 2022-26
requesting to add linear nonyl tri-mellitate
to the List. According to the petition, the
taxable chemical ethylene constitutes 53.90
percent by weight of the materials used to
produce linear nonyl tri-mellitate, based on
the predominant method of production.
(a) Determination. Linear nonyl
tri-mellitate is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of production:
The predominant method of production of
linear nonyl tri-mellitate is using an esteri-
fication reaction. The linear nonyl tri-mel-
litate tri-ester is made by reacting primary
C9 alcohol with trimellitic anhydride. The
ester is produced by esterification of three
moles of a linear C9 alcohol and one mole
of trimellitic anhydride in the presence of
an acidic catalyst.
By using excess alcohol (up to 30%
molar excess of C9 alcohol) and remov-
ing the water, the equilibrium is shifted
towards the formation of the tri-ester. The
reactants are charged into a reactor and
heated up. The reaction rate is acceler-
ated by using, for example, tetra-n-butyl
titanate introduced at high temperature
(140°C – 250°C), while removing the
water formed.
Excess alcohol is distilled from the
ester by vacuum prior to neutralization
and recycled into subsequent batches.
The final ester is purified by neutralizing
with a base such as an aqueous solution of
sodium carbonate. The remaining excess
water is distilled off and the ester is then
filtered using filter agents.
The degree of purity of the ester has a
minimum 99.0 wt%. The overall formula
is C
36
H
60
O
6
and the molecular weight is
589 g.mol-1, based on the carbon numbers
of the alkyl groups, with 9 carbons being
the predominant number and the average
(>97% C9). The alkyl groups typically
have methyl- or ethyl- branching, with on
average 0.3 branches per molecule typi-
cally found on the second carbon of the
alkyl chain closest to the aromatic ring.
The linear C9 alcohol is obtained
through hydroformylation of octene.
Octene is obtained through ethylene
oligomerization. Hydroformylation is
the reaction of ctene at high pressure and
temperature in the presence of a catalyst
with syngas (a mixture of carbon mon-
oxide and hydrogen). An alcohol with
one carbon atom higher versus the start-
ing olefin is obtained, hence octene gives
nonanol. The hydroformylation induces
0.3 branches per molecule predominantly
on the two-position carbon of the alcohol.
Trimellitic anhydride is obtained through
air oxidation of 1,2,4-trimethylbenzene.
(2) Stoichiometric material consump-
tion equation:
12 C
2
H
4
[ethylene] + 3 CO [carbon
monoxide] + 6 H
2
[hydrogen] +
C
9
H
4
O
5
[trimellitic anhydride] →
C
36
H
60
O
6
[linear nonyl tri-mellitate] +
2 H
2
O [water]
(3) Reasons for the determination:
The linear nonyl tri-mellitate petition was
filed on May 1, 2025. The notice of filing
summarizing the petition and requesting
comments was published in the Federal
Register (90 FR 21125) on May 16, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical eth-
ylene constitutes more than 20 percent
by weight of the materials used in the
production of linear nonyl tri-mellitate,
based on the predominant method of
production. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of lin-
ear nonyl tri-mellitate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $5.55 per ton. The conversion factor
for the ethylene used in the production of
linear nonyl tri-mellitate is 0.57. The tax
rate is calculated by multiplying the con-
version factor by the tax rate for ethylene:
(0.57 x $9.74 = $5.55).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 2917.39.20.00
(ii) Schedule B number: 2917.39.2000
(iii) CAS number: 220582-53-6
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
30. Determination to Add Neo
Decanoic Acid to the List
Exxon Mobil Corporation, an exporter
of neo decanoic acid, submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add neo decanoic acid to the
List. According to the petition, the taxable
chemical propylene constitutes 66.20 per-
cent by weight of the materials used to
produce neo decanoic acid, based on the
predominant method of production.
(a) Determination. Neo decanoic acid
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of production of
neo decanoic acid is Koch synthesis.

Bulletin No. 2025–41 469 October 6, 2025
(2) Stoichiometric material consump-
tion equation:
2.88 x 0.94 C
3
H
6
[propylene] + 2.88
x 0.06 C
5
H
10
[amylene] + CO [carbon
monoxide] + H
2
O [water] → C
10
H
20
O
2

[neo decanoic acid]
(3) Reasons for the determination:
The neo decanoic acid petition was filed
on May 1, 2025. The notice of filing
summarizing the petition and request-
ing comments was published in the Fed-
eral Register (90 FR 21824) on May 21,
2025. The Treasury Department and the
IRS received one non-substantive written
comment cautioning against the danger
of producing the substance in response to
the notice of filing. The comment did not
address whether neo decanoic acid meets
the weight or value test under section
4672(a)(2)(B). A public hearing was nei-
ther requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemical propylene con-
stitutes more than 20 percent by weight of
the materials used in the production of neo
decanoic acid, based on the predominant
method of production. Therefore, the test
in section 4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of neo
decanoic acid to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $6.43 per ton. The conversion factor
for the propylene used in the production of
neo decanoic acid is 0.66. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for propylene: (0.66
x $9.74 = $6.43).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 26896-20-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2915.90.18.00
(ii) Schedule B number: 2915.90.0000
31. Determination to Add Neo
Pentanoic Acid to the List
Exxon Mobil Corporation, an exporter
of neo pentanoic acid, submitted a peti-
tion in accordance with Rev. Proc. 2022-
26 requesting to add neo pentanoic acid
to the List. According to the petition, the
taxable chemical isobutylene (an isomer
of butylene) constitutes 54.90 percent by
weight of the materials used to produce
neo pentanoic acid, based on the predomi-
nant method of production.
(a) Determination. Neo pentanoic acid
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing neo pentanoic acid is via Koch syn-
thesis. Isobutylene is reacted with carbon
monoxide at >1000 psig and a highly
acidic (Lewis acid) catalyst (Koch reac-
tion) in a continuous, stirred tank reac-
tor. The acid is sent to a distillation tower
finishing section. Light rejects (paraffins,
olefins, and light acids) are removed,
prime neopentanoic acid is recovered
at high purity (>99.7 wt%), and acidic
byproducts removed.
(2) Stoichiometric material consump-
tion equation:
C
4
H
8
[isobutylene] + CO [carbon mon-
oxide] + H
2
O

[water]→ C
5
H
10
O
2
[neo
pentanoic acid]
(3) Reasons for the determination: The
neo pentanoic acid petition was filed on
May 1, 2025. The notice of filing sum-
marizing the petition and requesting
comments was published in the Federal
Register (90 FR 20346) on May 13, 2025.
The Treasury Department and the IRS
received no written comments in response
to the notice of filing. A public hearing
was neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemical isobutylene (an
isomer of butylene) constitutes more than
20 percent by weight of the materials
used in the production of neo pentanoic
acid, based on the predominant method of
production. Therefore, the test in section
4672(a)(2)(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of neo
pentanoic acid to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $5.36 per ton. The conversion factor
for the butylene used in the production of
neo pentanoic acid is 0.55. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for butylene: (0.55 x
$9.74 = $5.36)
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 2915.60.50.00
(ii) Schedule B number: 2915.60.0000
(iii) CAS number: 75-98-9
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
32. Determination to Add Nonene to
the List
Exxon Mobil Corporation, an exporter
of nonene, submitted a petition in accor-
dance with Rev. Proc. 2022-26 requesting
to add nonene to the List. According to
the petition, the taxable chemical propyl-
ene constitutes 90.50 percent by weight
of the materials used to produce nonene,
based on the predominant method of pro-
duction.
(a) Determination. Nonene is added to
the list of taxable substances under section
4672(a). Other pertinent information is as
follows:
(1) Predominant method of production:
The predominant method of producing
nonene is oligomerization.

October 6, 2025 470 Bulletin No. 2025–41
Nonene (C
9
H
18
) and tetramer (C
12
H
24
)
are olefins that are obtained by oligom-
erization of feedstock that contains pro-
pylene. Each product actually contains
several isomeric olefins with varying
degrees of branching and different posi-
tions of the olefinic double bond. Refin-
ery-generated propylene is of sufficient
quality to be used as the feedstock mate-
rial. The most common process initiates
the reaction with a supported phosphoric
acid catalyst at temperatures ranging
from 120°C to 225°C. Reaction tempera-
ture and feed composition determine the
range of olefins in a given product stream.
If the feedstock is a propylene-rich C3
stream, C9 and C12 olefins are the dom-
inant products. Some processes that use
a mixed C3/C4 feed generate a spectrum
of products that also includes heptene
(C7) and octene (C8). Distillation sep-
arates the mix into the desired product
fractions. Nonene and tetramer have
distillation ranges of 127°C-149°C and
182°C-215°C, respectively. Assuming
83 percent and 79 percent of theoreti-
cal yield for production of nonene and
tetramer, respectively, 1.21 and 1.27
units of propylene are consumed per unit
of nonene and tetramer produced, respec-
tively.
(2) Stoichiometric material consump-
tion equation:
2.88 x 0.94 C
3
H
6
[propylene] + 2.88
x 0.06 C
5
H
10
[amylene] → C
9
H
18

[nonene]
(3) Reasons for the determination:
The nonene petition was filed on May 1,
2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
21826) on May 21, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical propyl-
ene constitutes more than 20 percent by
weight of the materials used in the pro-
duction of nonene, based on the predom-
inant method of production. Therefore,
the test in section 4672(a)(2)(B) is sat-
isfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of non-
ene to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $8.77 per ton. The conversion factor
for the propylene used in the production of
nonene is 0.90. The tax rate is calculated
by multiplying the conversion factor by
the tax rate for propylene: (0.90 x $9.74
= $8.77).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 68526-55-6
5
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2901.29.50.00
(ii) Schedule B number: 2901.29.6000
33. Determination To Add Regular
Butyl Rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036,
y=88) to the List
Exxon Mobil Corporation, an exporter
of regular butyl rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036, y=88), submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add regular butyl rubber
((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036, y=88) to the
List. According to the petition, the taxable
chemical isobutylene (an isomer of buty-
lene) constitutes 98.50 percent by weight
of the materials used to produce regular
butyl rubber, based on the predominant
method of production.
(a) Determination. Regular butyl rub-
ber ((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036, y=88) is
added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing reg-
ular butyl rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036,
y=88) is via cationic copolymerization of
isobutylene with isoprene in the presence
of a catalyst. The catalyst system used is
typically composed of aluminum chloride,
boron trifluoride or similar with an initia-
tor dissolved in a methyl chloride solvent.
Monomer feed of isobutylene and isoprene
dissolved in a methyl chloride solvent are
fed to a reactor operated at approximately
-100⁰C to control the rapid exothermic
polymerization reaction generating a high
molecular weight regular butyl rubber
polymer. To obtain this high molecular
weight polymer, it is necessary for the feed
monomers to be as pure as possible as well
as ensuring that the feed system stays as
dry as possible. The methyl chloride and
unreacted monomers are flashed overhead
and recycled back to the feed system while
the polymer is precipitated out as a solid
which is baled and packaged.
(2) Stoichiometric material consump-
tion equation:
7036 C
4
H
8
[isobutylene] + 88 C
5
H
8

[isoprene] → [7036 C
4
H
8
+ 88 C
5
H
8
]
[butyl rubber]
(3) Reasons for the determination:
The regular butyl rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
;
x=7036, y=88) petition was filed on April
8, 2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
20347) on May 13, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemical isobutylene (an
isomer of butylene) constitutes more than
20 percent by weight of the materials used
in the production of regular butyl rubber
((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036, y=88), based on
5
The Notice of Filing for propylene erroneously stated that the CAS number is “68526-55-63.” This error is corrected here.

Bulletin No. 2025–41 471 October 6, 2025
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of regu-
lar butyl rubber ((C
4
H
8
)
x
(C
5
H
8
)
y
; x=7036,
y=88)to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $9.64 per ton. The conversion factor
for the butylene used in the production
of regular butyl rubber ((C4H8)x(C5H8)
y; x=7036, y=88) is 0.99. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for butylene: (0.99 x
$9.74 = $9.64).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 4002.31.0000
(ii) Schedule B number: 4002.31.0000
(iii) CAS number: 9010-85-9
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
34. Determination to Add Tridecyl
Alcohol to the List
Exxon Mobil Corporation, an exporter
of tridecyl alcohol, submitted a petition
in accordance with Rev. Proc. 2022-26
requesting to add tridecyl alcohol to the
List. According to the petition, the tax-
able chemical propylene constitutes 75.90
percent by weight of the materials used to
produce tridecyl alcohol, based on the pre-
dominant method of production.
(a) Determination. Tridecyl alcohol
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing tri-
decyl alcohol is oxonation.
Tridecyl alcohol is derived from the
oxo reaction with branched olefins. Refin-
ery-connected polygas units generate
many of these olefins as purified cuts or
fractions.
Most commercial plants for hydro-
formylation of higher olefins use only
cobalt hydrocarbonyl or modified
cobalt-phosphine catalysts. Separation
of Rh catalysts from higher aldehydes or
alcohols is more difficult and expensive.
In most cases for the plasticizer and deter-
gent alcohol ranges (C6-C15), producers
hydrogenate the aldehydes, which have no
commercial significance, to alcohols.
(2) Stoichiometric material consump-
tion equation:
3.85 x 0.94 C
3
H
6
[propylene] + 3.85
x 0.06 C
5
H
10
[amylene] + CO [car-
bon monoxide] + 2 H
2
[hydrogen] →
C
13
H
28
O [tridecyl alcohol]
(3) Reasons for the determination: The
tridecyl alcohol petition was filed on May
1, 2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
21824) on May 21, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical propyl-
ene constitutes more than 20 percent by
weight of the materials used in the pro-
duction of tridecyl alcohol, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of tride-
cyl alcohol to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $7.40 per ton. The conversion factor
for the propylene used in the production
of tridecyl alcohol is 0.76. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for propylene: (0.76
x $9.74 = $7.40).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 68526-86-3
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 3823.70.60.00
(ii) Schedule B number: 3823.70.6000
35. Determination to Add Tri-isononyl
Tri-mellitate to the List
Exxon Mobil Corporation, an exporter
of tri-isononyl tri-mellitate, submitted
a petition in accordance with Rev. Proc.
2022-26 requesting to add tri-isononyl
tri-mellitate to the List. According to the
petition, the taxable chemical propylene
constitutes 47.30 percent by weight of
the materials used to produce tri-isononyl
tri-mellitate, based on the predominant
method of production.
(a) Determination. Tri-isononyl
tri-mellitate is added to the list of taxable
substances under section 4672(a). Other
pertinent information is as follows:
(1) Predominant method of production:
The predominant method of producing tri-
isononyl tri-mellitate is via esterification.
This process can be readily carried
out in heated kettles with agitation and
provision for water takeoff. Esterifica-
tion catalysts (e.g., sulfuric acid or p-tol-
uenesulfonic acid) speed the reaction
and are neutralized, washed, and then
removed. The purity requirements for
commercial plasticizers are very high;
phthalate esters are usually colorless
and are mostly odorless. In the case of
phthalates, the esterification is carried
out through the reaction of phthalic
anhydride and 2-ethylhexanol to produce
dioctyl phthalate (DOP).
This reaction usually requires an
excess of alcohol, which is readily recy-
cled. Analogous syntheses yield aliphatic
dicarboxylic acid esters, benzoates, and
trimellitates.
The tri-isononyl tri-mellitate tri-ester is
made by reacting primary isononyl (C9)
alcohol with trimellitic anhydride. The
ester is produced by esterification of three

October 6, 2025 472 Bulletin No. 2025–41
moles of isononyl C9 alcohol and one
mole of trimellitic anhydride in the pres-
ence of a catalyst.
By using excess alcohol (up to 30%
molar excess of C9 alcohol) and remov-
ing the water, the equilibrium is shifted
towards the formation of the tri-ester. The
reactants are charged into a reactor and
heated up. The reaction rate is acceler-
ated by using, for example, tetra-n-butyl
titanate introduced at high temperature
(140°C-250°C), while removing the water
formed.
Excess alcohol is distilled from the
ester by vacuum prior to neutralization
and recycled into subsequent batches.
The final ester is purified by neutralizing
with a base such as an aqueous solution of
sodium carbonate. The remaining excess
water is distilled off and the ester is then
filtered using filter agents. The degree of
purity of the ester has a minimum 99.0
wt%.
(2) Stoichiometric material consump-
tion equation:
7.22 C
3
H
6
[propylene] + 0.46 C
5
H
10

[amylene] + 3 CO [carbon monoxide]
+ 6 H
2
[hydrogen] + C
9
H
4
O
5
[trimel-
litic anhydride] → C
36
H
60
O
6
[tri-
isononyl trimellitate] + 2 H
2
O [water]
(3) Reasons for the determination:
The tri-isononyl tri-mellitate petition
was filed on May 1, 2025. The notice
of filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 21827) on
May 21, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation and
other information in the petition shows
that the taxable chemical propylene con-
stitutes more than 20 percent by weight
of the materials used in the production of
tri-isononyl tri-mellitate, based on the pre-
dominant method of production. There-
fore, the test in section 4672(a)(2)(B) is
satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of tri-
isononyl tri-mellitate to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): July 1, 2022
(6) Tax rate prescribed by the Secre-
tary: $5.06 per ton. The conversion factor
for the propylene used in the production of
tri-isononyl tri-mellitate is 0.52. The tax
rate is calculated by multiplying the con-
version factor by the tax rate for propyl-
ene: (0.52 x $9.74 = $5.06).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 2917.39.20.00
(ii) Schedule B number: 2917.39.2000
(iii) CAS number: 53894-23-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
36. Determination to Add Di-
isobutylene to the List
TPC Group, Inc., an exporter of
di-isobutylene, submitted a petition in
accordance with Rev. Proc. 2022-26
requesting to add di-isobutylene to the
List. According to the petition, the taxable
chemical isobutylene (an isomer of buty-
lene) constitutes 100 percent by weight of
the materials used to produce di-isobuty-
lene, based on the predominant method of
production.
(a) Determination. Di-isobutylene is
added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing
di-isobutylene is the cationic dimerization
(polymerization) of isobutylene mono-
mers. An acid catalyst (typically a sulfonic
acid resin) and polar moderator are used
to generate a stable cation on the tertiary
carbon of isobutylene. This cation induces
a chain growth dimerization that incorpo-
rates isobutylene monomer. The catalyst is
not a component of the resulting di-isobu-
tylene.
(2) Stoichiometric material consump-
tion equation:
2 C
4
H
8
(isobutylene) → C
8
H
16

(di-isobutylene)
(3) Reasons for the determination: The
di-isobutylene petition was filed on April 8,
2025. The notice of filing summarizing the
petition and requesting comments was pub-
lished in the Federal Register (90 FR 20352)
on May 13, 2025. The Treasury Department
and the IRS received one non-substantive
written comment on the necessity of the
filing to understand its impact in response
to the notice of filing. A public hearing was
neither requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical buty-
lene constitutes more than 20 percent
by weight of the materials used in the
production of di-isobutylene, based on
the predominant method of production.
Therefore, the test in section 4672(a)(2)
(B) is satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of
di-isobutylene to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): October 1, 2024
(6) Tax rate prescribed by the Secre-
tary: $9.74 per ton. The conversion factor
for the isobutylene (an isomer of butylene)
used in the production of di-isobutylene is
1.00. The tax rate is calculated by mul-
tiplying the conversion factor by the tax
rate for butylene: (1.00 x $9.74 = $9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
number: CAS number: 25167-70-8
(2) The Secretary is unable to con-
firm the following proposed classification
numbers:
(i) HTSUS number: 2901.29.1050
(ii) Schedule B number: 2901.29.6000

Bulletin No. 2025–41 473 October 6, 2025
37. Determination to Add
Polyisobutylene to the List
TPC Group, Inc., an exporter of poly-
isobutylene, submitted a petition in accor-
dance with Rev. Proc. 2022-26 request-
ing to add polyisobutylene to the List.
According to the petition, the taxable
chemical isobutylene (an isomer of buty-
lene) constitutes 100 percent by weight of
the materials used to produce polyisobu-
tylene, based on the predominant method
of production.
(a) Determination. Polyisobutylene
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of production:
The predominant method of producing
polyisobutylene is the cationic polymer-
ization of isobutylene monomers. A Lewis
acid catalyst and proton donating initiator
are used to generate a stable cation on the
tertiary carbon of isobutylene. This cation
induces a chain growth polymerization
that continues to transfer the cation to the
end of the polymer chain making it avail-
able for further incorporation of isobuty-
lene monomer. The size of the polymer is
dictated by the reaction temperature such
that the lower the temperature the larger
the polymer.
(2) Stoichiometric material consump-
tion equation:
n C
4
H
8
(isobutylene) → (C
4
H
8
)
n
(poly-
isobutylene)
(3) Reasons for the determination:
The polyisobutylene petition was filed
on February 14, 2025. The notice of
filing summarizing the petition and
requesting comments was published in
the Federal Register (90 FR 14521) on
April 2, 2025. The Treasury Department
and the IRS received no written com-
ments in response to the notice of filing.
A public hearing was neither requested
nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemical isobu-
tylene (an isomer of butylene) consti-
tutes more than 20 percent by weight of
the materials used in the production of
polyisobutylene, based on the predomi-
nant method of production. Therefore,
the test in section 4672(a)(2)(B) is sat-
isfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of poly-
isobutylene to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): October 1, 2024
(6) Tax rate prescribed by the Secre-
tary: $9.74 per ton. The conversion factor
for the butylene used in the production of
polyisobutylene is 1.00. The tax rate is
calculated by multiplying the conversion
factor by the tax rate for butylene: (1.00 x
$9.74 = $9.74).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 3902.20.10.00 and
3902.20.50.00
(ii) Schedule B number: 3902.20.1000
and 3902.20.5000
(iii) CAS number: 9003-27-4
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
38. Determination to Add Styrene-
acrylonitrile ((C
3
H
3
N)
a
-(C
8
H
8
)
s
; a=0.26,
s=0.74) to the List
Trinseo LLC, an importer and exporter
of styrene-acrylonitrile ((C
3
H
3
N)
a
-(C
8
H
8
)
s
; a=0.26, s=0.74), also known as “SAN,”
submitted a petition in accordance with
Rev. Proc. 2022-26 requesting to add SAN
to the List. According to the petition, the
taxable chemicals propylene, ammonia,
benzene, and ethylene constitute 88.27
percent by weight of the materials used to
produce SAN, based on the predominant
method of production.
(a) Determination. Styrene-acryloni-
trile ((C
3
H
3
N)
a
-(C
8
H
8
)
s
; a=0.26, s=0.74)
is added to the list of taxable substances
under section 4672(a). Other pertinent
information is as follows:
(1) Predominant method of produc-
tion: The predominant method of produc-
ing SAN is through free radical, random
copolymerization of 100 percent of the
acrylonitrile and styrene monomers. Low
levels of unreacted monomers remain
bound within the polymer matrix as
“residual” components of the product as
sold or imported.
(2) Stoichiometric material consump-
tion equation:
a C
3
H
6
(propylene) + a NH
3
(ammo-
nia) + 3/2a O
2
+ s C
6
H
6
(benzene) + s
C
2
H
4
(ethylene) → (C
3
H
3
N)
a
-(C
8
H
8
)
s
(SAN) + 3a H
2
O + s H
2
(hydrogen);
a=0.26, s=0.74
(3) Reasons for the determination: The
SAN petition was filed on February 14,
2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
14693) on April 3, 2025, and a correction
was published in the Federal Register (90
FR 19246) on May 6, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals pro-
pylene, ammonia, benzene, and eth-
ylene constitute more than 20 percent
by weight of the materials used in the
production of SAN, based on the pre-
dominant method of production. There-
fore, the test in section 4672(a)(2)(B) is
satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of SAN
to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): April 1, 2024
(6) Tax rate prescribed by the Secre-
tary: $9.91 per ton. The conversion fac-

October 6, 2025 474 Bulletin No. 2025–41
tors for the taxable chemicals used in the
production of SAN are 0.12 for propylene,
0.05 for ammonia, 0.64 for benzene, and
0.23 for ethylene. The tax rate is calcu-
lated by adding the products of the con-
version factor for each taxable chemical
and the tax rate for that taxable chemical:
((0.12 x $9.74) + (0.05 x $5.28) + (0.64 x
$9.74) + (0.23 x $9.74) = $9.91).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 3903.20.0000 (Pel-
lets)
(ii) Schedule B number: 3903.20.0000
(Pellets)
(iii) CAS number: 9003-54-7
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
39. Determination to Add Acrylonitrile
Butadiene Styrene ((C
3
H
3
N)
a
-(C
4
H
6
)
b
-(C
8
H
8
)
s
; a=0.16, b=0.10, s=0.74) to the
List
Trinseo LLC, an importer and
exporter of acrylonitrile butadiene sty-
rene ((C
3
H
3
N)
a
-(C
4
H
6
)
b
-(C
8
H
8
)
s
; a=0.16,
b=0.10, s=0.74), also known as “ABS,”
submitted a petition in accordance with
Rev. Proc. 2022-26 requesting to add
ABS to the List. According to the peti-
tion, the taxable chemicals propylene,
ammonia, butadiene, benzene, and eth-
ylene constitute 92.40 percent by weight
of the materials used to produce ABS,
based on the predominant method of pro-
duction.
(a) Determination. Acrylonitrile buta-
diene styrene ((C
3
H
3
N)
a
-(C
4
H
6
)
b
-(C
8
H
8
)
s
; a=0.16, b=0.10, s=0.74) is added to the
list of taxable substances under section
4672(a). Other pertinent information is as
follows:
(1) Predominant method of production:
The predominant method of producing
ABS is through free radical, random copo-
lymerization of 100 percent of the acry-
lonitrile, butadiene, and styrene mono-
mers. Low levels of unreacted monomers
remain bound within the polymer matrix
as “residual” components of the product
as sold or imported.
(2) Stoichiometric material consump-
tion equation:
a C
3
H
6
(propylene) + a NH
3
(ammo-
nia) + 3/2a O
2
+ b C
4
H
6
(butadiene) +
s C
6
H
6
(benzene) + s C
2
H
4
(ethylene)
→ (C
3
H
3
N)
a
-(C
4
H
6
)
b
-(C
8
H
8
)
s
(ABS)
+ 3a H
2
O (water) + s H
2
(hydrogen);
a=0.16, b=0.10, s=0.74
(3) Reasons for the determination: The
ABS petition was filed on February 14,
2025. The notice of filing summarizing
the petition and requesting comments was
published in the Federal Register (90 FR
14687) on April 3, 2025, and a correction
was published in the Federal Register (90
FR 19245) on May 6, 2025. The Treasury
Department and the IRS received no writ-
ten comments in response to the notice
of filing. A public hearing was neither
requested nor held.
The Secretary followed the process
in section 4672(a)(2)(B) in making this
determination. A review of the stoichio-
metric material consumption equation
and other information in the petition
shows that the taxable chemicals propyl-
ene, ammonia, butadiene, benzene, and
ethylene constitute more than 20 percent
by weight of the materials used in the
production of ABS, based on the pre-
dominant method of production. There-
fore, the test in section 4672(a)(2)(B) is
satisfied.
(4) Date of determination: September
15, 2025.
(5) Effective dates for addition of ABS
to the List:
(i) Effective date for purposes of the
section 4671 tax (see section 11.01 of Rev.
Proc. 2022-26): January 1, 2026
(ii) Effective date for purposes of refund
claims under section 4662(e) (see sections
11.02 and 11.03 of Rev. Proc. 2022-26, as
modified by section 3 of Rev. Proc. 2023-
20): April 1, 2024
(6) Tax rate prescribed by the Secre-
tary: $9.90 per ton. The conversion fac-
tors for the taxable chemicals used in the
production of ABS are 0.07 for propylene,
0.03 for ammonia, 0.06 for butadiene,
0.64 for benzene, and 0.23 for ethylene.
The tax rate is calculated by adding the
products of the conversion factor for each
taxable chemical and the tax rate that
chemical: ((0.07 x $9.74) + (0.03 x $5.28)
+ (0.06 x $9.74) + (0.64 x $9.74) + (0.23 x
$9.74) = $9.90).
(b) Classification numbers.
(1) The Secretary has no basis to object
to the following proposed classification
numbers:
(i) HTSUS number: 3903.30.0000 (Pel-
lets)
(ii) Schedule B number: 3903.30.0000
(Pellets)
(iii) CAS number: 9003-56-9
(2) The Secretary is unable to con-
firm the following proposed classification
numbers: Not applicable.
Krishna P. Vallabhaneni,
Tax Legislative Counsel.
Extension of Replacement
Period for Livestock Sold
on Account of Drought
Notice 2025-52
SECTION 1. PURPOSE
This notice provides guidance regard-
ing an extension of the replacement period
under § 1033(e) of the Internal Revenue
Code for livestock sold on account of
drought in specified counties.
SECTION 2. BACKGROUND
.01 Nonrecognition of Gain on Invol-
untary Conversion of Livestock. Section
1033(a) generally provides for nonrec-
ognition of gain when property is invol-
untarily converted and replaced with
property that is similar or related in ser-
vice or use. Section 1033(e)(1) provides
that a sale or exchange of livestock (other
than poultry) held by a taxpayer for draft,
breeding, or dairy purposes in excess of
the number that would be sold following
the taxpayer’s usual business practices is
treated as an involuntary conversion if the
livestock is sold or exchanged solely on
account of drought, flood, or other weath-
er-related conditions.
.02 Replacement Period. Section
1033(a)(2)(A) generally provides that
gain from an involuntary conversion is
recognized only to the extent the amount
realized on the conversion exceeds the
cost of replacement property purchased
during the replacement period. If a sale

Bulletin No. 2025–41 475 October 6, 2025
or exchange of livestock is treated as an
involuntary conversion under § 1033(e)
(1) and is solely on account of drought,
flood, or other weather-related conditions
that result in the area being designated as
eligible for assistance by the federal gov-
ernment, § 1033(e)(2)(A) provides that the
replacement period ends four years after
the close of the first taxable year in which
any part of the gain from the conversion is
realized. Section 1033(e)(2)(B) provides
that the Secretary may extend this replace-
ment period on a regional basis for such
additional time as the Secretary deter-
mines appropriate if the weather-related
conditions that resulted in the area being
designated as eligible for assistance by
the federal government continue for more
than three years. Section 1033(e)(2) is
effective for any taxable year with respect
to which the due date (without regard to
extensions) for a taxpayer’s return is after
December 31, 2002.
SECTION 3. EXTENSION OF
REPLACEMENT PERIOD UNDER
§ 1033(e)(2)(B)
Notice 2006-82, 2006-2 C.B. 529,
provides for extensions of the replace-
ment period under § 1033(e)(2)(B). If a
sale or exchange of livestock is treated as
an involuntary conversion on account of
drought and the taxpayer’s replacement
period is determined under § 1033(e)
(2)(A), the replacement period will be
extended under § 1033(e)(2)(B) and
Notice 2006-82 until the end of the tax-
payer’s first taxable year ending after the
first drought-free year for the applicable
region. For this purpose, the first drought-
free year for the applicable region is the
first 12-month period that (1) ends August
31; (2) ends in or after the last year of the
taxpayer’s four-year replacement period
determined under § 1033(e)(2)(A); and
(3) does not include any weekly period
for which exceptional, extreme, or severe
drought is reported for any location in the
applicable region. The applicable region
is the county that experienced the drought
conditions on account of which the live-
stock was sold or exchanged and all coun-
ties that are contiguous to that county.
A taxpayer may determine whether
exceptional, extreme, or severe drought is
reported for any location in the applicable
region by reference to U.S. Drought Mon-
itor maps that are produced on a weekly
basis by the National Drought Mitigation
Center. U.S. Drought Monitor maps are
archived at https://droughtmonitor.unl.
edu/Maps/MapArchive.aspx.
In addition, Notice 2006-82 provides
that the Internal Revenue Service will
publish in September of each year a list of
counties
1
for which exceptional, extreme,
or severe drought was reported during the
preceding 12 months. Taxpayers may use
this list instead of U.S. Drought Monitor
maps to determine whether exceptional,
extreme, or severe drought has been
reported for any location in the applicable
region.
The Appendix to this notice contains
the list of counties for which exceptional,
extreme, or severe drought was reported
during the 12-month period ending August
31, 2025. Under Notice 2006-82, the
12-month period ended on August 31,
2025, is not a drought-free year for an
applicable region that includes any county
on this list. Accordingly, for a taxpayer
who qualified for a four-year replacement
period for livestock sold or exchanged on
account of drought and whose replacement
period is scheduled to expire at the end of
2025 (or, in the case of a fiscal year tax-
payer, at the end of the taxable year that
includes August 31, 2025), the replacement
period will be extended under § 1033(e)
(2) and Notice 2006-82 if the applicable
region includes any county on this list. This
extension will continue until the end of the
taxpayer’s first taxable year ending after a
drought-free year for the applicable region.
SECTION 4. DRAFTING
INFORMATION
The principal author of this notice is
personnel from the Office of Associate
Chief Counsel (Income Tax & Account-
ing). For further information regarding
this notice, please contact the Office of
Associate Chief Counsel (Income Tax &
Accounting), Branch 8 at (202) 317-7009
(not a toll-free number).
APPENDIX
Alabama
Counties of Autauga, Baldwin, Barbour,
Bibb, Blount, Bullock, Butler, Calhoun,
Chambers, Cherokee, Chilton, Choctaw,
Clarke, Clay, Cleburne, Coffee, Colbert,
Conecuh, Coosa, Covington, Crenshaw,
Cullman, Dale, Dallas, DeKalb, Elmore,
Escambia, Etowah, Fayette, Franklin,
Geneva, Greene, Hale, Henry, Houston,
Jackson, Jefferson, Lamar, Lauderdale,
Lawrence, Lee, Limestone, Lowndes,
Macon, Madison, Marengo, Marion,
Marshall, Mobile, Monroe, Montgomery,
Morgan, Perry, Pickens, Pike, Randolph,
Russell, Saint Clair, Shelby, Sumter, Tal-
ladega, Tallapoosa, Tuscaloosa, Walker,
Washington, Wilcox, and Winston.
Arizona
Counties of Apache, Cochise,
Coconino, Gila, Graham, Greenlee, La
Paz, Maricopa, Mohave, Navajo, Pima,
Pinal, Santa Cruz, Yavapai, and Yuma.
Arkansas
Counties of Arkansas, Ashley, Baxter,
Benton, Boone, Bradley, Calhoun, Car-
roll, Chicot, Clark, Cleburne, Cleveland,
Columbia, Conway, Crawford, Critten-
den, Dallas, Desha, Faulkner, Franklin,
Fulton, Garland, Grant, Hempstead, Hot
Spring, Howard, Independence, Izard,
Jefferson, Johnson, Lafayette, Lee, Lin-
coln, Little River, Logan, Lonoke, Madi-
son, Marion, Miller, Mississippi, Monroe,
Montgomery, Nevada, Newton, Ouachita,
Perry, Phillips, Pike, Polk, Pope, Prairie,
Pulaski, Saline, Scott, Searcy, Sebastian,
Sevier, Sharp, Stone, Union, Van Buren,
Washington, and Yell.
California
Counties of Imperial, Inyo, Kern, Los
Angeles, Mono, Orange, Riverside, San
Bernardino, San Diego, Santa Barbara,
Siskiyou, and Ventura.
1
While Notice 2006-82 uses the term “counties,” this notice lists other applicable regions as well (e.g., boroughs, parishes, etc.).

October 6, 2025 476 Bulletin No. 2025–41
Colorado
Counties of Adams, Arapahoe,
Archuleta, Baca, Bent, Boulder, Broom-
field, Chaffee, Cheyenne, Clear Creek,
Conejos, Costilla, Custer, Delta, Den-
ver, Dolores, Douglas, Eagle, El Paso,
Fremont, Garfield, Gilpin, Grand, Gun-
nison, Hinsdale, Huerfano, Jackson,
Jefferson, Kiowa, Kit Carson, Lake, La
Plata, Larimer, Las Animas, Lincoln,
Logan, Mesa, Mineral, Moffat, Mont-
ezuma, Montrose, Otero, Ouray, Park,
Pitkin, Prowers, Pueblo, Rio Blanco,
Rio Grande, Routt, Saguache, San Juan,
San Miguel, Sedgwick, Summit, Teller,
and Weld.
Connecticut
Counties of Fairfield, Hartford, Litch-
field, Middlesex, New Haven, New Lon-
don, Tolland, and Windham.
Delaware
Counties of Kent, New Castle, and
Sussex.
District of Columbia
District of Columbia.
Florida
Counties of Alachua, Bay, Brevard,
Broward, Calhoun, Charlotte, Citrus, Col-
lier, DeSoto, Escambia, Flagler, Gadsden,
Glades, Gulf, Hardee, Hendry, Hernando,
Highlands, Hillsborough, Holmes, Indian
River, Jackson, Lake, Lee, Leon, Levy,
Liberty, Manatee, Marion, Martin, Miami-
Dade, Monroe, Okaloosa, Okeechobee,
Orange, Osceola, Palm Beach, Pasco,
Pinellas, Polk, Putnam, Saint Johns, Saint
Lucie, Santa Rosa, Sarasota, Seminole,
Sumter, Volusia, Wakulla, Walton, and
Washington.
Georgia
Counties of Banks, Barrow, Bartow,
Catoosa, Chattahoochee, Chattooga,
Cherokee, Clay, Cobb, Columbia, Dade,
Dawson, Decatur, DeKalb, Douglas,
Early, Elbert, Fannin, Floyd, Forsyth,
Franklin, Fulton, Gilmer, Gordon, Gwin-
nett, Habersham, Hall, Harris, Hart, Jack-
son, Lincoln, Lumpkin, McDuffie, Miller,
Murray, Muscogee, Paulding, Pickens,
Polk, Quitman, Rabun, Randolph, Sem-
inole, Stephens, Stewart, Taliaferro,
Towns, Union, Walker, Warren, White,
Whitfield, and Wilkes.
Hawaii
Counties of Hawaii, Honolulu, Kala-
wao, Kauai, and Maui.
Idaho
Counties of Bannock, Bear Lake,
Benewah, Bingham, Blaine, Boise, Bon-
ner, Bonneville, Boundary, Butte, Camas,
Caribou, Cassia, Clark, Clearwater,
Custer, Elmore, Franklin, Fremont, Good-
ing, Idaho, Jefferson, Jerome, Kootenai,
Latah, Lemhi, Lewis, Lincoln, Madison,
Minidoka, Nez Perce, Oneida, Owyhee,
Power, Shoshone, Teton, Twin Falls, and
Valley.
Illinois
Counties of Adams, Alexander, Boone,
Brown, Bureau, Calhoun, Carroll, Cham-
paign, Clark, Coles, Cook, DeKalb,
Douglas, DuPage, Edgar, Ford, Grundy,
Hancock, Iroquois, Jersey, Jo Daviess,
Kane, Kankakee, Kendall, Lake, La Salle,
Lee, Livingston, McDonough, McHenry,
McLean, Madison, Marshall, Massac,
Ogle, Peoria, Piatt, Pike, Pope, Pulaski,
Putnam, Rock Island, Saint Clair, Schuy-
ler, Stephenson, Tazewell, Union, Ver-
milion, Whiteside, Will, Winnebago, and
Woodford.
Indiana
Counties of Adams, Allen, Benton,
Blackford, Carroll, Cass, Clark, Clinton,
Dearborn, DeKalb, Delaware, Elkhart,
Fountain, Franklin, Fulton, Grant, How-
ard, Huntington, Jasper, Jay, Jefferson,
Jennings, Kosciusko, LaGrange, Lake,
LaPorte, Madison, Marshall, Miami,
Newton, Noble, Ohio, Porter, Posey,
Pulaski, Randolph, Ripley, Saint Joseph,
Spencer, Starke, Steuben, Switzerland,
Tippecanoe, Tipton, Vanderburgh, Ver-
million, Wabash, Warren, Warrick, Wells,
White, and Whitley.
Iowa
Counties of Adair, Adams, Allamakee,
Audubon, Benton, Black Hawk, Bremer,
Buchanan, Buena Vista, Butler, Carroll,
Cass, Cedar, Cerro Gordo, Cherokee,
Chickasaw, Clay, Clayton, Clinton, Craw-
ford, Delaware, Dickinson, Dubuque,
Emmet, Fayette, Floyd, Franklin, Fre-
mont, Greene, Grundy, Guthrie, Hamil-
ton, Hancock, Hardin, Harrison, Howard,
Humboldt, Ida, Iowa, Jackson, Johnson,
Jones, Kossuth, Linn, Lyon, Marshall,
Mills, Mitchell, Monona, Montgomery,
O’Brien, Osceola, Page, Palo Alto, Plym-
outh, Pottawattamie, Poweshiek, Shelby,
Sioux, Tama, Webster, Winnebago, Win-
neshiek, Woodbury, and Wright.
Kansas
Counties of Allen, Anderson, Atchi-
son, Barber, Bourbon, Brown, Butler,
Chase, Chautauqua, Cherokee, Cheyenne,
Clark, Clay, Cloud, Comanche, Cowley,
Crawford, Decatur, Dickinson, Doniphan,
Douglas, Edwards, Elk, Finney, Frank-
lin, Geary, Grant, Greenwood, Hamilton,
Harper, Harvey, Jackson, Jefferson, Jew-
ell, Johnson, Kearny, Kingman, Kiowa,
Labette, Lane, Leavenworth, Linn, Logan,
Lyon, McPherson, Marion, Marshall,
Meade, Miami, Mitchell, Montgomery,
Morris, Morton, Nemaha, Neosho, Nor-
ton, Osage, Osborne, Ottawa, Phillips,
Pottawatomie, Pratt, Rawlins, Reno,
Republic, Riley, Saline, Scott, Sedg-
wick, Seward, Shawnee, Sheridan, Sher-
man, Smith, Stafford, Stanton, Stevens,
Sumner, Thomas, Wabaunsee, Wallace,
Washington, Wichita, Wilson, Woodson,
and Wyandotte.
Kentucky
Counties of Allen, Anderson, Ballard,
Boone, Bourbon, Boyd, Boyle, Breckin-
ridge, Butler, Caldwell, Calloway, Camp-
bell, Carlisle, Carroll, Carter, Christian,
Crittenden, Daviess, Elliott, Franklin,
Fulton, Gallatin, Grant, Graves, Grayson,
Green, Greenup, Hardin, Harrison, Hen-
derson, Henry, Hickman, Hopkins, John-
son, Kenton, Larue, Lawrence, Living-
ston, Logan, Lyon, McCracken, McLean,
Magoffin, Marion, Marshall, Martin,
Meade, Mercer, Morgan, Muhlenberg,

Bulletin No. 2025–41 477 October 6, 2025
Nelson, Ohio, Oldham, Owen, Pendle-
ton, Scott, Shelby, Simpson, Taylor, Todd,
Trigg, Trimble, Union, Warren, Washing-
ton, Webster, and Woodford.
Louisiana
Parishes of Acadia, Allen, Avoyelles,
Beauregard, Bienville, Bossier, Caddo,
Calcasieu, Cameron, Claiborne, Con-
cordia, De Soto, East Baton Rouge, East
Carroll, East Feliciana, Evangeline, Iber-
ville, Jefferson Davis, Lafayette, Lincoln,
Morehouse, Pointe Coupee, Saint Helena,
Saint Landry, Saint Martin, Tangipahoa,
Union, Vermilion, Vernon, Webster, West
Baton Rouge, West Carroll, and West Feli-
ciana.
Maine
Counties of Hancock, Kennebec,
Knox, Lincoln, Penobscot, Waldo, Wash-
ington, and York.
Maryland
City of Baltimore. Counties of Alle-
gany, Anne Arundel, Baltimore, Calvert,
Caroline, Carroll, Cecil, Charles,
Dorchester, Frederick, Garrett, Harford,
Howard, Kent, Montgomery, Prince
George’s, Queen Anne’s, Saint Mary’s,
Somerset, Talbot, Washington, Wicomico,
and Worcester.
Massachusetts
Counties of Berkshire, Bristol, Essex,
Franklin, Hampden, Hampshire, Mid-
dlesex, Norfolk, Plymouth, Suffolk, and
Worcester.
Michigan
Counties of Alcona, Alger, Allegan,
Alpena, Antrim, Arenac, Baraga, Barry,
Bay, Benzie, Charlevoix, Cheboygan,
Chippewa, Clare, Clinton, Crawford,
Delta, Dickinson, Eaton, Emmet, Glad-
win, Gogebic, Grand Traverse, Gratiot,
Hillsdale, Houghton, Huron, Ionia, Iosco,
Iron, Isabella, Kalkaska, Kent, Lake,
Leelanau, Lenawee, Luce, Mackinac,
Manistee, Marquette, Mason, Mecosta,
Menominee, Midland, Missaukee, Mon-
roe, Montcalm, Montmorency, Muskegon,
Newaygo, Ogemaw, Ontonagon, Osceola,
Oscoda, Otsego, Ottawa, Presque Isle,
Roscommon, Saginaw, Sanilac, School-
craft, Tuscola, and Wexford.
Minnesota
Counties of Aitkin, Becker, Beltrami,
Big Stone, Blue Earth, Brown, Carl-
ton, Cass, Chippewa, Clay, Clearwater,
Cook, Cottonwood, Crow Wing, Doug-
las, Faribault, Fillmore, Grant, Houston,
Hubbard, Itasca, Jackson, Koochiching,
Lac qui Parle, Lake, Lake of the Woods,
Lincoln, Lyon, Mahnomen, Martin, Mille
Lacs, Morrison, Mower, Murray, Nicol-
let, Nobles, Norman, Olmsted, Otter
Tail, Pine, Pipestone, Redwood, Ren-
ville, Rock, Roseau, Saint Louis, Stevens,
Swift, Todd, Traverse, Wabasha, Wadena,
Watonwan, Wilkin, Winona, and Yellow
Medicine.
Mississippi
Counties of Amite, Attala, Bolivar,
Calhoun, Carroll, Chickasaw, Choctaw,
Clay, Coahoma, Forrest, George, Greene,
Grenada, Holmes, Humphreys, Issaquena,
Itawamba, Jackson, Jones, Kemper,
Lafayette, Leake, Lee, Leflore, Lown-
des, Marshall, Monroe, Montgomery,
Neshoba, Noxubee, Oktibbeha, Panola,
Perry, Pike, Pontotoc, Quitman, Sharkey,
Stone, Sunflower, Tallahatchie, Tishom-
ingo, Tunica, Union, Walthall, Washing-
ton, Wayne, Webster, Wilkinson, Winston,
and Yalobusha.
Missouri
City of Saint Louis. Counties of Atchi-
son, Audrain, Barry, Barton, Bates, Ben-
ton, Bollinger, Buchanan, Camden, Cape
Girardeau, Cass, Cedar, Christian, Clay,
Clinton, Cole, Crawford, Dade, Dallas,
Dent, Douglas, Franklin, Gasconade,
Greene, Henry, Hickory, Holt, Jackson,
Jasper, Johnson, Knox, Laclede, Lafay-
ette, Lawrence, Lewis, McDonald, Macon,
Madison, Maries, Marion, Miller, Missis-
sippi, Moniteau, Monroe, Morgan, New
Madrid, Newton, Osage, Ozark, Pettis,
Phelps, Pike, Platte, Polk, Pulaski, Ralls,
Randolph, Ray, Saint Charles, Saint Clair,
Saint Louis, Scott, Shelby, Stoddard, Stone,
Taney, Vernon, Wayne, and Webster.
Montana
Counties of Beaverhead, Big Horn,
Blaine, Broadwater, Carbon, Carter, Cas-
cade, Chouteau, Custer, Daniels, Dawson,
Deer Lodge, Fallon, Flathead, Gallatin,
Garfield, Glacier, Granite, Hill, Jefferson,
Judith Basin, Lake, Lewis and Clark, Lib-
erty, Lincoln, McCone, Madison, Mea-
gher, Mineral, Missoula, Park, Phillips,
Pondera, Powder River, Powell, Prairie,
Ravalli, Richland, Roosevelt, Rosebud,
Sanders, Sheridan, Silver Bow, Teton,
Toole, Valley, and Wibaux.
Nebraska
Counties of Adams, Antelope, Arthur,
Banner, Blaine, Boone, Box Butte, Boyd,
Brown, Buffalo, Burt, Butler, Cass, Cedar,
Chase, Cherry, Cheyenne, Clay, Colfax,
Cuming, Custer, Dakota, Dawes, Dawson,
Deuel, Dixon, Dodge, Douglas, Fillmore,
Franklin, Frontier, Furnas, Gage, Garden,
Garfield, Gosper, Grant, Greeley, Hall,
Hamilton, Harlan, Hayes, Hitchcock,
Holt, Hooker, Howard, Jefferson, John-
son, Kearney, Keith, Keya Paha, Kimball,
Knox, Lancaster, Lincoln, Logan, Loup,
McPherson, Madison, Merrick, Morrill,
Nance, Nemaha, Nuckolls, Otoe, Pawnee,
Perkins, Phelps, Pierce, Platte, Polk, Red
Willow, Richardson, Rock, Saline, Sarpy,
Saunders, Scotts Bluff, Seward, Sheri-
dan, Sherman, Sioux, Stanton, Thayer,
Thomas, Thurston, Valley, Washington,
Wayne, Webster, Wheeler, and York.
Nevada
Counties of Clark, Elko, Esmeralda,
Eureka, Humboldt, Lander, Lincoln, Min-
eral, Nye, and White Pine.
New Hampshire
Counties of Cheshire, Hillsborough,
Rockingham, and Strafford.
New Jersey
Counties of Atlantic, Bergen, Burling-
ton, Camden, Cape May, Cumberland,
Essex, Gloucester, Hudson, Hunterdon,
Mercer, Middlesex, Monmouth, Morris,
Ocean, Passaic, Salem, Somerset, Sussex,
Union, and Warren.

October 6, 2025 478 Bulletin No. 2025–41
New Mexico
Counties of Bernalillo, Catron, Chaves,
Cibola, Colfax, DeBaca, Dona Ana, Eddy,
Grant, Guadalupe, Harding, Hidalgo, Lea,
Lincoln, Los Alamos, Luna, McKinley,
Mora, Otero, Rio Arriba, Roosevelt, San-
doval, San Juan, San Miguel, Santa Fe,
Sierra, Socorro, Taos, Torrance, Union,
and Valencia.
New York
Counties of Bronx, Columbia, Dela-
ware, Dutchess, Greene, Kings, Nassau,
New York, Orange, Putnam, Queens,
Rensselaer, Richmond, Rockland, Scho-
harie, Suffolk, Sullivan, Ulster, and West-
chester.
North Carolina
Counties of Anson, Beaufort, Bertie,
Bladen, Brunswick, Camden, Carteret,
Cherokee, Chowan, Clay, Columbus, Cra-
ven, Cumberland, Currituck, Dare, Duplin,
Graham, Greene, Haywood, Hoke, Hyde,
Jackson, Jones, Lenoir, Macon, Martin,
Moore, New Hanover, Onslow, Pamlico,
Pasquotank, Pender, Perquimans, Pitt,
Richmond, Robeson, Scotland, Swain,
Transylvania, Tyrrell, and Washington.
North Dakota
Counties of Adams, Billings, Bot-
tineau, Bowman, Burke, Cass, Dickey,
Divide, Dunn, Golden Valley, Grant, Het-
tinger, McKenzie, McLean, Mercer, Mor-
ton, Mountrail, Oliver, Ransom, Renville,
Richland, Sargent, Slope, Stark, Ward,
and Williams.
Ohio
Counties of Adams, Allen, Ashland,
Athens, Auglaize, Belmont, Brown, But-
ler, Carroll, Champaign, Clark, Clermont,
Clinton, Columbiana, Coshocton, Craw-
ford, Defiance, Delaware, Erie, Fairfield,
Fayette, Franklin, Fulton, Gallia, Greene,
Guernsey, Hamilton, Hancock, Hardin,
Harrison, Henry, Highland, Hocking,
Holmes, Huron, Jackson, Jefferson, Knox,
Lawrence, Licking, Logan, Lucas, Madi-
son, Mahoning, Marion, Meigs, Mercer,
Miami, Monroe, Montgomery, Morgan,
Morrow, Muskingum, Noble, Ottawa,
Paulding, Perry, Pickaway, Pike, Por-
tage, Preble, Putnam, Richland, Ross,
Sandusky, Scioto, Seneca, Shelby, Stark,
Trumbull, Tuscarawas, Union, Van Wert,
Vinton, Warren, Washington, Wayne, Wil-
liams, Wood, and Wyandot.
Oklahoma
Counties of Adair, Alfalfa, Atoka,
Beaver, Beckham, Blaine, Bryan, Caddo,
Canadian, Carter, Cherokee, Choctaw,
Coal, Comanche, Cotton, Craig, Creek,
Custer, Delaware, Dewey, Ellis, Garfield,
Garvin, Grady, Grant, Greer, Harmon,
Harper, Hughes, Jackson, Jefferson, John-
ston, Kay, Kingfisher, Kiowa, Latimer, Le
Flore, Lincoln, Logan, Love, McClain,
McCurtain, McIntosh, Major, Mar-
shall, Mayes, Murray, Muskogee, Noble,
Nowata, Okfuskee, Oklahoma, Okmulgee,
Osage, Ottawa, Pawnee, Payne, Pittsburg,
Pontotoc, Pottawatomie, Pushmataha,
Roger Mills, Rogers, Seminole, Stephens,
Texas, Tillman, Tulsa, Wagoner, Washing-
ton, Washita, Woods, and Woodward.
Oregon
Counties of Baker, Benton, Clackamas,
Clatsop, Columbia, Crook, Curry, Doug-
las, Gilliam, Grant, Harney, Hood River,
Jackson, Jefferson, Josephine, Klamath,
Lane, Lincoln, Linn, Malheur, Marion,
Morrow, Multnomah, Polk, Sherman,
Tillamook, Umatilla, Union, Wallowa,
Wasco, Washington, Wheeler, and Yam-
hill.
Pennsylvania
Counties of Adams, Allegheny, Beaver,
Bedford, Berks, Bucks, Cambria, Carbon,
Chester, Columbia, Dauphin, Delaware,
Fayette, Franklin, Fulton, Greene, Indi-
ana, Lackawanna, Lancaster, Lawrence,
Lebanon, Lehigh, Luzerne, Mercer, Mon-
roe, Montgomery, Montour, Northamp-
ton, Northumberland, Philadelphia,
Pike, Schuylkill, Somerset, Washington,
Wayne, Westmoreland, and York.
Rhode Island
Counties of Kent, Providence, and
Washington.
South Carolina
Counties of Abbeville, Anderson,
Berkeley, Charleston, Chesterfield, Clar-
endon, Colleton, Darlington, Dillon,
Dorchester, Edgefield, Florence, George-
town, Greenwood, Horry, Kershaw, Lau-
rens, Lee, McCormick, Marion, Marlboro,
Oconee, Pickens, Saluda, Sumter, and
Williamsburg.
South Dakota
Counties of Aurora, Beadle, Bennett,
Bon Homme, Brookings, Brown, Brule,
Buffalo, Butte, Campbell, Charles Mix,
Clark, Clay, Codington, Corson, Custer,
Davison, Day, Deuel, Dewey, Doug-
las, Edmunds, Fall River, Faulk, Grant,
Gregory, Haakon, Hamlin, Hand, Han-
son, Harding, Hughes, Hutchinson, Hyde,
Jackson, Jerauld, Jones, Kingsbury, Lake,
Lawrence, Lincoln, Lyman, McCook,
McPherson, Marshall, Meade, Mel-
lette, Miner, Minnehaha, Moody, Oglala
Lakota, Pennington, Perkins, Potter, Rob-
erts, Sanborn, Spink, Stanley, Sully, Todd,
Tripp, Turner, Union, Walworth, Yankton,
and Ziebach.
Tennessee
Counties of Anderson, Bedford, Ben-
ton, Bledsoe, Blount, Bradley, Campbell,
Cannon, Carroll, Cheatham, Chester,
Clay, Cocke, Coffee, Cumberland, David-
son, Decatur, DeKalb, Dickson, Dyer,
Fentress, Franklin, Gibson, Giles, Grundy,
Hamilton, Hardin, Henderson, Henry,
Hickman, Houston, Humphreys, Jackson,
Jefferson, Knox, Lake, Lauderdale, Law-
rence, Lewis, Lincoln, Loudon, McMinn,
McNairy, Macon, Marion, Marshall,
Maury, Meigs, Monroe, Montgomery,
Moore, Morgan, Obion, Overton, Perry,
Pickett, Polk, Putnam, Rhea, Roane, Rob-
ertson, Rutherford, Scott, Sequatchie,
Sevier, Shelby, Smith, Stewart, Sumner,
Tipton, Trousdale, Union, Van Buren,
Warren, Wayne, Weakley, White, Wil-
liamson, and Wilson.
Texas
Counties of Anderson, Andrews,
Angelina, Aransas, Archer, Armstrong,
Atascosa, Austin, Bailey, Bandera, Bas-

Bulletin No. 2025–41 479 October 6, 2025
trop, Baylor, Bee, Bell, Bexar, Blanco,
Borden, Bosque, Bowie, Brazoria, Bra-
zos, Brewster, Briscoe, Brooks, Brown,
Burleson, Burnet, Caldwell, Calhoun,
Callahan, Cameron, Camp, Carson, Cass,
Castro, Chambers, Cherokee, Childress,
Clay, Cochran, Coke, Coleman, Collin,
Collingsworth, Colorado, Comal, Concho,
Cooke, Coryell, Cottle, Crane, Crockett,
Crosby, Culberson, Dallas, Dawson, Deaf
Smith, Delta, Denton, DeWitt, Dickens,
Dimmit, Donley, Duval, Eastland, Ector,
Edwards, Ellis, El Paso, Falls, Fannin,
Fayette, Fisher, Floyd, Foard, Fort Bend,
Franklin, Freestone, Frio, Gaines, Galves-
ton, Garza, Gillespie, Glasscock, Goliad,
Gonzales, Gray, Grayson, Gregg, Grimes,
Guadalupe, Hale, Hall, Hardeman, Hardin,
Harris, Harrison, Haskell, Hays, Hemphill,
Henderson, Hidalgo, Hockley, Hopkins,
Houston, Howard, Hudspeth, Hunt, Irion,
Jack, Jackson, Jasper, Jeff Davis, Jeffer-
son, Jim Hogg, Jim Wells, Jones, Karnes,
Kaufman, Kendall, Kenedy, Kent, Kerr,
Kimble, King, Kinney, Kleberg, Knox,
Lamar, Lamb, Lampasas, La Salle,
Lavaca, Lee, Leon, Liberty, Limestone,
Lipscomb, Live Oak, Llano, Loving,
Lubbock, Lynn, McCulloch, McLennan,
McMullen, Madison, Marion, Martin,
Mason, Matagorda, Maverick, Medina,
Menard, Midland, Milam, Mills, Mitchell,
Montague, Montgomery, Morris, Motley,
Nacogdoches, Navarro, Newton, Nolan,
Nueces, Ochiltree, Orange, Palo Pinto,
Panola, Parker, Parmer, Pecos, Polk, Pot-
ter, Presidio, Rains, Randall, Reagan,
Real, Red River, Reeves, Refugio, Rob-
erts, Robertson, Rockwall, Runnels, Rusk,
San Augustine, San Jacinto, San Patricio,
San Saba, Schleicher, Scurry, Shackel-
ford, Shelby, Smith, Starr, Stephens, Ster-
ling, Stonewall, Sutton, Swisher, Tarrant,
Taylor, Terrell, Terry, Throckmorton,
Titus, Tom Green, Travis, Trinity, Tyler,
Upshur, Upton, Uvalde, Val Verde, Van
Zandt, Victoria, Walker, Waller, Ward,
Washington, Webb, Wharton, Wheeler,
Wichita, Wilbarger, Willacy, Williamson,
Wilson, Winkler, Wise, Wood, Yoakum,
Young, Zapata, and Zavala.
Utah
Counties of Beaver, Box Elder,
Cache, Carbon, Daggett, Davis, Duch-
esne, Emery, Garfield, Grand, Iron, Juab,
Kane, Millard, Morgan, Piute, Rich, Salt
Lake, San Juan, Sanpete, Sevier, Summit,
Tooele, Uintah, Utah, Wasatch, Washing-
ton, and Wayne.
Vermont
Counties of Bennington and Windham.
Virginia
Cities of Alexandria, Chesapeake, Cov-
ington, Fairfax, Falls Church, Fredericks-
burg, Hampton, Harrisonburg, Manassas,
Manassas Park, Newport News, Norfolk,
Poquoson, Portsmouth, Staunton, Virginia
Beach, and Waynesboro. Counties of
Accomack, Albemarle, Alleghany, Arling-
ton, Augusta, Bath, Bland, Botetourt,
Caroline, Clarke, Craig, Culpeper, Essex,
Fairfax, Fauquier, Frederick, Giles,
Gloucester, Greene, Highland, King and
Queen, King George, King William,
Lancaster, Loudoun, Madison, Mathews,
Middlesex, Montgomery, Northampton,
Northumberland, Orange, Page, Prince
William, Pulaski, Richmond, Roanoke,
Rockbridge, Rockingham, Shenandoah,
Spotsylvania, Stafford, Tazewell, Warren,
Westmoreland, and York.
Washington
Counties of Adams, Asotin, Ben-
ton, Chelan, Clallam, Clark, Columbia,
Cowlitz, Douglas, Ferry, Franklin, Gar-
field, Grant, Grays Harbor, Island, Jef-
ferson, King, Kitsap, Kittitas, Klickitat,
Lewis, Lincoln, Okanogan, Pend Oreille,
Pierce, Skagit, Skamania, Snohomish,
Spokane, Stevens, Thurston, Walla Walla,
Whatcom, Whitman, and Yakima.
West Virginia
Counties of Barbour, Berkeley, Boone,
Braxton, Brooke, Cabell, Calhoun, Clay,
Doddridge, Fayette, Gilmer, Grant, Green-
brier, Hampshire, Hancock, Hardy, Harri-
son, Jackson, Jefferson, Kanawha, Lewis,
Lincoln, Logan, McDowell, Marion, Mar-
shall, Mason, Mercer, Mineral, Mingo,
Monongalia, Monroe, Morgan, Nicholas,
Ohio, Pendleton, Pleasants, Pocahon-
tas, Preston, Putnam, Raleigh, Randolph,
Ritchie, Roane, Summers, Taylor, Tucker,
Tyler, Upshur, Wayne, Webster, Wetzel,
Wirt, Wood, and Wyoming.
Wisconsin
Counties of Ashland, Barron, Bay-
field, Brown, Buffalo, Burnett, Crawford,
Dodge, Door, Douglas, Florence, Forest,
Grant, Green, Iowa, Iron, Jefferson, Keno-
sha, Kewaunee, Lafayette, Langlade, Lin-
coln, Marathon, Marinette, Menominee,
Milwaukee, Oconto, Oneida, Ozaukee,
Price, Racine, Rock, Rusk, Sawyer, Sha-
wano, Vernon, Vilas, Walworth, Wash-
burn, Washington, and Waukesha.
Wyoming
Counties of Albany, Big Horn, Camp-
bell, Carbon, Converse, Crook, Fremont,
Goshen, Hot Springs, Johnson, Laramie,
Lincoln, Natrona, Niobrara, Park, Platte,
Sheridan, Sublette, Sweetwater, Teton,
Uinta, Washakie, and Weston.
Guam
Island of Guam.
Republic of the Marshall Islands
Atolls of Ailinglapalap, Jaluit, Kwaja-
lein, Utirik, and Wotje.
Federated States of Micronesia
State of Pingelap.
Commonwealth of the Northern Mariana
Islands
Islands of Rota, Saipan, and Tinian.
2025-2026 Special Per
Diem Rates
Notice 2025-54
SECTION 1. PURPOSE
This annual notice provides the 2025-
2026 special per diem rates for taxpay-
ers to use in substantiating the amount of
ordinary and necessary business expenses

October 6, 2025 480 Bulletin No. 2025–41
incurred while traveling away from home,
specifically (1) the special transportation
industry meal and incidental expenses
(M&IE) rates, (2) the rate for the inciden-
tal expenses only deduction, and (3) the
rates and list of high-cost localities for
purposes of the high-low substantiation
method.
SECTION 2. BACKGROUND
Rev. Proc. 2019-48, 2019-51 I.R.B.
1392 (or successor), provides rules for
using a per diem rate to substantiate, under
§ 274(d) of the Internal Revenue Code and
§ 1.274-5 of the Income Tax Regulations,
the amount of ordinary and necessary
business expenses paid or incurred while
traveling away from home. Taxpayers
using the rates and list of high-cost local-
ities provided in this notice must comply
with Rev. Proc. 2019-48 (or successor).
Notice 2024-68, 2024-41 I.R.B. 729, pro-
vides the rates and list of high-cost local-
ities for the period October 1, 2024, to
September 30, 2025.
SECTION 3. SPECIAL M&IE RATES
FOR TRANSPORTATION INDUSTRY
The special M&IE rates for taxpayers
in the transportation industry are $80 for
any locality of travel in the continental
United States (CONUS) and $86 for any
locality of travel outside the continental
United States (OCONUS). See section
4.04 of Rev. Proc. 2019-48 (or succes-
sor).
SECTION 4. RATE FOR INCIDENTAL
EXPENSES ONLY DEDUCTION
The rate for any CONUS or OCO-
NUS locality of travel for the incidental
expenses only deduction is $5 per day.
See section 4.05 of Rev. Proc. 2019-48 (or
successor).
SECTION 5. HIGH-LOW
SUBSTANTIATION METHOD
1. Annual high-low rates. For pur-
poses of the high-low substantiation
method, the per diem rates in lieu of the
rates described in Notice 2024-68 (the
per diem substantiation method) are
$319 for travel to any high-cost locality
and $225 for travel to any other locality
within CONUS. The amount of the $319
high rate and $225 low rate that is treated
as paid for meals for purposes of § 274(n)
is $86 for travel to any high-cost locality
and $74 for travel to any other locality
within CONUS. See section 5.02 of Rev.
Proc. 2019-48 (or successor). The per
diem rates in lieu of the rates described in
Notice 2024-68 (the meal and incidental
expenses only substantiation method) are
$86 for travel to any high-cost locality
and $74 for travel to any other locality
within CONUS.
2. High-cost localities. The following
localities have a federal per diem rate of
$272 or more, and are high-cost localities
for the specified portion of the calendar
year:
Key CityCounty or Other Defined LocationPortion of Calendar Year
Alabama
Gulf ShoresBaldwinJune 1 – July 31
Arizona
Phoenix/ScottsdaleMaricopaFebruary 1 – March 31
SedonaCity limits of SedonaOctober 1 – December 31 and March 1 – September 30
California
Los AngelesLos Angeles, Orange, and Ventura,
and Edwards AFB, less the city of
Santa Monica
October 1 – September 30
Mammoth LakesMonoDecember 1 – March 31
MontereyMontereyOctober 1 – September 30
NapaNapaOctober 1 – November 30 and February 1 – September 30
Palm SpringsRiversideOctober 1 – April 30
San DiegoSan DiegoOctober 1 – September 30
San FranciscoSan FranciscoOctober 1 – September 30
San Luis ObispoSan Luis ObispoJune 1 – July 31
Santa BarbaraSanta BarbaraOctober 1 – September 30
Santa MonicaCity limits of Santa MonicaOctober 1 – September 30
South Lake TahoeEl DoradoDecember 1 – March 31
Sunnyvale/Palo Alto/San JoseSanta ClaraOctober 1 – September 30
Yosemite National ParkMariposaJanuary 1 – April 30

Bulletin No. 2025–41 481 October 6, 2025
Key CityCounty or Other Defined LocationPortion of Calendar Year
Colorado
AspenPitkinOctober 1 – September 30
Denver/AuroraDenver, Adams, Arapahoe, and
Jefferson
October 1 – October 31 and April 1 – September 30
Silverthorne/BreckenridgeSummitDecember 1 – March 31
Steamboat SpringsRouttDecember 1 – March 31
TellurideSan MiguelOctober 1 – September 30
VailEagleOctober 1 – September 30
Delaware
LewesSussexJune 1 – August 31
District of Columbia
Washington, D.C. (also the cities of Alexandria, Falls Church, and
Fairfax, and the counties of Arlington and Fairfax, in Virginia; and the
counties of Montgomery and Prince George’s in Maryland) (See also
Maryland and Virginia)
October 1 – September 30
Florida
Boca Raton/Delray Beach/
Jupiter
Palm Beach and HendryJanuary 1 – April 30
BradentonManateeFebruary 1 – March 31
Cocoa BeachBrevardFebruary 1 – March 31
Fort LauderdaleBrowardJanuary 1 – April 30
Fort MyersLeeJanuary 1 – March 31
Fort Walton Beach/DeFuniak
Springs
Okaloosa and WaltonJune 1 – July 31
Gulf BreezeSanta RosaJune 1 – July 31
Key WestMonroeOctober 1 – September 30
MiamiMiami-DadeDecember 1 – May 31
NaplesCollierDecember 1 – April 30
Panama CityBayJune 1 – July 31
SarasotaSarasotaFebruary 1 – April 30
SebringHighlandsFebruary 1 – March 31
StuartMartinFebruary 1 – March 31
Tampa/St. PetersburgPinellas and HillsboroughFebruary 1 – April 30
Vero BeachIndian RiverDecember 1 – April 30
Georgia
AtlantaFulton and DeKalbJanuary 1 – March 31
Jekyll Island/BrunswickGlynnMarch 1 – July 31
Idaho
BoiseAdaOctober 1 – October 31 and June 1 – September 30
Coeur d’AleneKootenaiJune 1 – August 31
Sun Valley/KetchumBlaine and ElmoreDecember 31 – March 31 and June 1 – September 30
Illinois
ChicagoCook and LakeOctober 1 – November 30 and April 1 – September 30

October 6, 2025 482 Bulletin No. 2025–41
Key CityCounty or Other Defined LocationPortion of Calendar Year
Maine
Bar Harbor/RockportHancock and KnoxOctober 1 – October 31 and May 1 – September 30
Kennebunk/Kittery/SanfordYorkJuly 1 – August 31
PortlandCumberland and SagadahocOctober 1 – October 31 and June 1 – September 30
Maryland
Ocean CityWorcesterJune 1 – August 31
Washington, D.C.
Metropolitan Area
Montgomery and Prince George’sOctober 1 – September 30
Massachusetts
Boston/CambridgeSuffolk and city of CambridgeOctober 1 – September 30
FalmouthCity limits of FalmouthJuly 1 – August 31
HyannisBarnstable less the city of FalmouthJuly 1 – August 31
Martha’s VineyardDukesOctober 1 – September 30
NantucketNantucketJune 1 – September 30
Michigan
Mackinac IslandMackinacJuly 1 – August 31
PetoskeyEmmetJune 1 – August 31
Traverse CityGrand TraverseJuly 1 – August 31
Minnesota
DuluthSt. LouisOctober 1 – October 31 and June 1 – September 30
Montana
Big Sky/West Yellowstone/
Gardiner
Gallatin and ParkJune 1 – September 30
Kalispell/WhitefishFlatheadJuly 1 – September 30
New Jersey
Toms RiverOceanJuly 1 – August 31
New York
Glens FallsWarrenJuly 1 – August 31
Lake PlacidEssexJuly 1 – August 31
New York CityBronx, Kings, New York, Queens, and
Richmond
October 1 – December 31 and March 1 – September 30
Saratoga Springs/
Schenectady
Saratoga and SchenectadyJuly 1 – August 31
North Carolina
Kill Devil HillsDareJune 1 – August 31
Oregon
BendDeschutesJune 1 – August 31
Eugene/FlorenceLaneJune 1 – July 31
SeasideClatsopJuly 1 – August 31
Pennsylvania
HersheyHersheyJune 1 – August 31
PhiladelphiaPhiladelphiaOctober 1 – November 30 and April 1 – September 30
Rhode Island
Jamestown/Middletown/
Newport
NewportOctober 1 – October 31 and June 1 – September 30

Bulletin No. 2025–41 483 October 6, 2025
Key CityCounty or Other Defined LocationPortion of Calendar Year
South Carolina
CharlestonCharleston, Berkeley, and DorchesterOctober 1 – September 30
Hilton HeadBeaufortMarch 1 – August 31
Tennessee
NashvilleDavidsonOctober 1 – September 30
Utah
MoabGrandOctober 1 – October 31, March 1 – June 30, and
September 1 – September 30
Park CitySummitOctober 1 – September 30
Vermont
BurlingtonChittendenOctober 1 – October 31 and May 1 – September 30
ManchesterBenningtonOctober 1 – October 31 and August 1 – September 30
MontpelierWashingtonOctober 1 – October 31 and August 1 – September 30
Virginia
Virginia BeachCity of Virginia BeachJune 1 – August 31
Wallops IslandAccomackJuly 1 – August 31
Washington, D.C.
Metropolitan Area
Cities of Alexandria, Falls Church,
and Fairfax; counties of Arlington and
Fairfax
October 1 – September 30
Washington
Port Angeles/Port TownsendClallam and JeffersonJuly 1 – August 31
SeattleKingOctober 1 – September 30
Wyoming
Jackson/PinedaleTeton and SubletteOctober 1 – September 30
3. Changes in high-cost localities.
There are no changes in the list of high-
cost localities in this notice from the list of
high-cost localities in section 5 of Notice
2024-68.
SECTION 6. EFFECTIVE DATE
This notice is effective for per diem
allowances for lodging, meal and inci-
dental expenses, or for meal and inci-
dental expenses only, that are paid to any
employee on or after October 1, 2025, for
travel away from home on or after October
1, 2025. For purposes of computing the
amount allowable as a deduction for travel
away from home, this notice is effective
for meal and incidental expenses or for
incidental expenses only paid or incurred
on or after October 1, 2025. See sections
4.06 and 5.04 of Rev. Proc. 2019-48 (or
successor) for transition rules for the last
3 months of calendar year 2025.
SECTION 7. EFFECT ON OTHER
DOCUMENTS
Notice 2024-68 is superseded.
DRAFTING INFORMATION
The principal author of this notice is C.
Dylan Durham of the Office of Associate
Chief Counsel (Income Tax & Account-
ing). For further information regarding
this notice, contact Mr. Durham at 202-
317-7005 (not a toll-free number).

Bulletin No. 2025–41 i October 6, 2025
Definition of Terms
Revenue rulings and revenue procedures
(hereinafter referred to as “rulings”) that
have an effect on previous rulings use the
following defined terms to describe the
effect:
Amplified describes a situation where
no change is being made in a prior pub-
lished position, but the prior position is
being extended to apply to a variation of
the fact situation set forth therein. Thus,
if an earlier ruling held that a principle
applied to A, and the new ruling holds that
the same principle also applies to B, the
earlier ruling is amplified. (Compare with
modified, below).
Clarified is used in those instances
where the language in a prior ruling is
being made clear because the language
has caused, or may cause, some confu-
sion. It is not used where a position in a
prior ruling is being changed.
Distinguished describes a situation
where a ruling mentions a previously pub-
lished ruling and points out an essential
difference between them.
Modified is used where the substance
of a previously published position is being
changed. Thus, if a prior ruling held that a
principle applied to A but not to B, and the
new ruling holds that it applies to both A
and B, the prior ruling is modified because
it corrects a published position. (Compare
with amplified and clarified, above).
Obsoleted describes a previously pub-
lished ruling that is not considered deter-
minative with respect to future transactions.
This term is most commonly used in a ruling
that lists previously published rulings that
are obsoleted because of changes in laws or
regulations. A ruling may also be obsoleted
because the substance has been included in
regulations subsequently adopted.
Revoked describes situations where the
position in the previously published ruling
is not correct and the correct position is
being stated in a new ruling.
Superseded describes a situation where
the new ruling does nothing more than
restate the substance and situation of a
previously published ruling (or rulings).
Thus, the term is used to republish under
the 1986 Code and regulations the same
position published under the 1939 Code
and regulations. The term is also used
when it is desired to republish in a single
ruling a series of situations, names, etc.,
that were previously published over a
period of time in separate rulings. If the
new ruling does more than restate the sub-
stance of a prior ruling, a combination of
terms is used. For example, modified and
superseded describes a situation where the
substance of a previously published ruling
is being changed in part and is continued
without change in part and it is desired to
restate the valid portion of the previously
published ruling in a new ruling that is
self contained. In this case, the previously
published ruling is first modified and then,
as modified, is superseded.
Supplemented is used in situations in
which a list, such as a list of the names of
countries, is published in a ruling and that
list is expanded by adding further names
in subsequent rulings. After the original
ruling has been supplemented several
times, a new ruling may be published that
includes the list in the original ruling and
the additions, and supersedes all prior rul-
ings in the series.
Suspended is used in rare situations
to show that the previous published rul-
ings will not be applied pending some
future action such as the issuance of new
or amended regulations, the outcome of
cases in litigation, or the outcome of a
Service study.
Abbreviations
The following abbreviations in current
use and formerly used will appear in
material published in the Bulletin.
A—Individual.
Acq.—Acquiescence.
B—Individual.
BE—Beneficiary.
BK—Bank.
B.T.A.—Board of Tax Appeals.
C—Individual.
C.B.—Cumulative Bulletin.
CFR—Code of Federal Regulations.
CI—City.
COOP—Cooperative.
Ct.D.
—Court Decision.
CY—County.
D—Decedent.
DC—Dummy Corporation.
DE—Donee.
Del. Order—Delegation Order.
DISC—Domestic International Sales Corporation.
DR—Donor.
E—Estate.
EE—Employee.
E.O.—Executive Order.
ER—Employer.
ERISA—Employee Retirement Income Security Act.
EX—Executor.
F—Fiduciary.
FC—Foreign Country.
FICA—Federal Insurance Contributions Act.
FISC—Foreign International Sales Company.
FPH—Foreign Personal Holding Company.
F.R.—Federal Register.
FUTA—Federal Unemployment Tax Act.
FX—Foreign corporation.
G.C.M.—Chief Counsel’s Memorandum.
GE—Grantee.
GP—General Partner.
GR—Grantor.
IC—Insurance Company.
I.R.B.—Internal Revenue Bulletin.
LE—Lessee.
LP—Limited Partner.
LR—Lessor.
M—Minor.
Nonacq.—Nonacquiescence.
O—Organization.
P—Parent Corporation.
PHC—Personal Holding Company.
PO—Possession of the U.S.
PR—Partner.
PRS—Partnership.
PTE—Prohibited Transaction Exemption.
Pub. L.—Public Law.
REIT—Real Estate Investment Trust.
Rev. Proc.—Revenue Procedure.
Rev. Rul.—Revenue Ruling.
S—Subsidiary.
S.P.R.—Statement of Procedural Rules.
Stat.—Statutes at Large.
T—Target Corporation.
T.C.—Tax Court.
T.D.—Treasury Decision.
TFE—Transferee.
TFR—Transferor.
T.I.R.—Technical Information Release.
TP—Taxpayer.
TR—Trust.
TT—Trustee.
U.S.C.—United States Code.
X—Corporation.
Y—Corporation.
Z—Corporation.

October 6, 2025 ii Bulletin No. 2025–41
Numerical Finding List
1
Bulletin 2025–41
Announcements:
2025-19, 2025-29 I.R.B. 191
2025-20, 2025-31 I.R.B. 271
2025-21, 2025-32 I.R.B. 312
2025-24, 2025-36 I.R.B. 359
2025-25, 2025-36 I.R.B. 360
2025-26, 2025-40 I.R.B. 444
Notices:
2025-32, 2025-27 I.R.B. 1
2025-33, 2025-27 I.R.B. 4
2025-34, 2025-27 I.R.B. 6
2025-35, 2025-27 I.R.B. 8
2025-31, 2025-28 I.R.B. 14
2025-36, 2025-30 I.R.B. 192
2025-37, 2025-30 I.R.B. 198
2025-40, 2025-31 I.R.B. 266
2025-39, 2025-32 I.R.B. 308
2025-28, 2025-34 I.R.B. 316
2025-41, 2025-34 I.R.B. 325
2025-42, 2025-36 I.R.B. 351
2025-43, 2025-36 I.R.B. 356
2025-44, 2025-37 I.R.B. 386
2025-45, 2025-37 I.R.B. 388
2025-38, 2025-38 I.R.B. 392
2025-47, 2025-40 I.R.B. 441
2025-51, 2025-41 I.R.B. 448
2025-52, 2025-41 I.R.B. 474
2025-54, 2025-41 I.R.B. 479
Proposed Regulations:
REG-125710-18, 2025-30 I.R.B. 263
REG-107459-24, 2025-32 I.R.B. 313
REG-132805-17, 2025-35 I.R.B. 342
REG-108822-25, 2025-36 I.R.B. 361
REG-129260-16, 2025-39 I.R.B. 410
Revenue Procedures:
2025-22, 2025-30 I.R.B. 200
2025-24, 2025-31 I.R.B. 273
2025-25, 2025-32 I.R.B. 311
2025-26, 2025-33 I.R.B. 315
2025-28, 2025-38 I.R.B. 393
Revenue Rulings:
2025-13, 2025-28 I.R.B. 11
2025-14, 2025-32 I.R.B. 300
2025-15, 2025-32 I.R.B. 302
2025-16, 2025-35 I.R.B. 342
2025-17, 2025-36 I.R.B. 349
2025-18, 2025-37 I.R.B. 365
Revenue Rulings:—Continued
2025-19, 2025-41 I.R.B. 445
2025-20, 2025-41 I.R.B. 447
Treasury Decisions:
10021, 2025-31 I.R.B. 264
10031, 2025-32 I.R.B. 304
10033, 2025-40 I.R.B. 411
1
A cumulative list of all revenue rulings, revenue procedures, Treasury decisions, etc., published in Internal Revenue Bulletins 2025–27 through 2025–52 is in Internal Revenue Bulletin
2025–52, dated December 22, 2025.

Bulletin No. 2025–41 iii October 6, 2025
Finding List of Current Actions on
Previously Published Items
1
Bulletin 2025–41
1
A cumulative list of all revenue rulings, revenue procedures, Treasury decisions, etc., published in Internal Revenue Bulletins 2025–27 through 2025–52 is in Internal Revenue Bulletin
2025–52, dated December 22, 2025.

Internal Revenue Service
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