ECLI:EU:C:2026:751

Gesamter Gesetzestext

Provisional text

OPINION OF ADVOCATE GENERAL

ANDREA BIONDI

delivered on 10 September 2026 (1)

Case C‑835/24 P

European Commission

( Appeal – Civil service – Retirement pension – Transfer to the pension scheme of the EU institutions of pension rights acquired before entry into the service of the European Union – The ‘minimum subsistence figure’ rule – Application for reimbursement of the transferred capital – Unjust enrichment – Concept of ‘valid legal basis’ – Principle of equal treatment )

I. Introduction

1. By this appeal, Ms PT, the appellant, seeks the setting aside of a judgment handed down by the General Court of the European Union (2) by which the latter dismissed her action seeking reimbursement of the capital representing the national pension rights which she had acquired prior to taking up her post and subsequently transferred to the Pension Scheme of the European Union Institutions (‘the PSEUI’). That action was based on a single plea in law relating to the European Union’s unjust enrichment. The applicant has brought a second action, based on the same facts, alleging the unlawfulness of the fourth paragraph of Article 77 of the Staff Regulations of Officials of the European Union (‘the Staff Regulations’), which was also dismissed by a judgment that is also being challenged, in parallel. (3)

2. The dispute arises from the transfer by the applicant – who was at the time a member of the contract staff of the European Commission – of her national pension rights. In 2013, the national pension fund paid in the sum of EUR 201 271.60 in that regard to the PSEUI. After deducting the amounts relating to the regularisation of periods of auxiliary service and the revaluation of the capital, as well as the portion exceeding the maximum number of qualifying pensionable years of service – amounting to EUR 24 805.75 and immediately reimbursed to the applicant – the net capital of EUR 131 237.16 resulted in the recognition of a pension credit equivalent to twelve pensionable years, ten months and seventeen days. At the time of the applicant’s early retirement, the administration carried out the two calculations provided for in Article 77 of the Staff Regulations: the standard calculation, including the pensionable years of service so credited, resulted in a monthly amount of EUR 1 635.38; the ‘minimum subsistence figure’ rule, on the other hand, resulted in an amount of EUR 1 662.29. The latter amount, which was more favourable, was awarded to the applicant. Consequently, the pensionable years credited by virtue of the transfer had no practical effect on the amount of the pension.

3. The applicant contends that, in those circumstances, the European Union’s retention of the transferred capital constitutes unjust enrichment, and seeks its restitution. In the judgment under appeal, the General Court dismissed that claim, holding that the pension had been calculated in accordance with the applicable provisions and that, therefore, the enrichment was not without a valid legal basis.

II. Legal context

A. The Staff Regulations of Officials of the European Union

4. The second and fourth paragraphs of Article 77 of the Staff Regulations, provides as follows:

‘The maximum retirement pension shall be 70% of the final basic salary carried by the last grade in which the official was classified for at least one year.

…

The amount of the retirement pension must not be less than 4% of the minimum subsistence figure per year of service.

…’

5. Article 11(2) of Annex VIII to the Staff Regulations provides:

‘An official who enters the service of the Union after:

– leaving the service of a government administration or of a national or international organization; or

– pursuing an activity in an employed or self-employed capacity,

shall be entitled, after establishment but before becoming eligible for payment of a retirement pension within the meaning of Article 77 of the Staff Regulations, to have paid to the Union the capital value, updated to the date of the actual transfer, of pension rights acquired by virtue of such service or activities.

In such case the appointing authority of the institution in which the official serves shall, taking into account the official’s basic salary, age and exchange rate at the date of application for a transfer, determine by means of general implementing provisions the number of pensionable years with which he shall be credited under the Union pension scheme in respect of the former period of service, on the basis of the capital transferred, after deducting an amount representing capital appreciation between the date of the application for a transfer and the actual date of the transfer.’

6. Article 2 of Annex VIII to the Staff Regulations, for its part, governs the calculation of the retirement pension on the basis of the pensionable years taken into account.

B. The general implementing provisions

7. The general implementing provisions for Articles 11 and 12 of Annex VIII to the Staff Regulations (‘the GIPs’) govern the transfer procedures. In particular, Article 7(6) of the applicable GIPs provides that the number of years of pensionable service to be taken into account may under no circumstances exceed the number of pensionable years during which the person concerned was registered with the social security schemes of origin, and that any excess amount resulting from the capping of the years of pensionable service is to be reimbursed to the staff member concerned.

III. The appeal

8. The central issue in this appeal is the concept of a ‘valid legal basis’ for the European Union’s unjust enrichment. More specifically, the question of principle is whether the existence of statutory provisions which correctly govern the calculation of the retirement pension constitutes, in itself, a valid legal basis for the European Union to retain the transferred capital, even where the application of those provisions has not produced any concrete positive effect on the staff member’s financial situation.

9. The appellant asks the Court to set aside the judgment under appeal, to uphold her claim at first instance – specifically, the application for reimbursement of the transferred capital – and to order the Commission to pay the costs of both proceedings.

10. The Commission, supported by the Council of the European Union, as intervener, asks the Court to dismiss the appeal and to order the applicant to pay the costs. The Union Syndicale Fédérale/European Public Service Union – Court of Justice (‘the USF/EPSU-CJ’), an intervener in support of the appellant, supports the appellant’s claim.

11. At the Court’s request, this Opinion will focus on the second ground of appeal and, in particular, on its first, second and fourth complaints. By the first and second complaints, the appellant, supported by the USF/EPSU-CJ, challenges paragraphs 38 to 46 of the judgment under appeal, alleging that the General Court erred in characterising Article 77 of the Staff Regulations and Article 11(2) of Annex VIII thereto as a ‘valid legal basis’ for the European Union’s enrichment. By the fourth complaint, which is divided into two parts, the appellant alleges a breach of the principle of equal treatment. As regards the other grounds of appeal and complaints, I believe their manifest inadmissibility or unfoundedness, already correctly established by the General Court, calls for no further examination.

IV. Preliminary observations

12. Before examining the grounds of appeal, it is worth recalling the context of the present case. The pension scheme of the EU institutions is a defined-benefit scheme, based on the principle of solidarity. The pension received by an official or staff member does not exactly correspond to the contributions he or she has paid: the contributions form part of a solidarity-based scheme, and the pension is determined in accordance with Staff Regulations rules, not on the basis of an individual account.

13. In that context, Article 11(2) of Annex VIII to the Staff Regulations grants officials the right – but not the obligation – to transfer to the PSEUI the capital representing pension rights acquired prior to taking up their post. The transferred capital is converted, in accordance with predetermined actuarial criteria, into a number of pensionable years which are taken into account in the standard calculation of the pension. The option to transfer is intended to facilitate coordination between national schemes and the EU scheme, and to ensure that previously accrued entitlements are taken into account at the end of one’s career.

14. The calculation of the retirement pension, however, follows a two-part mechanism: on the one hand, the standard calculation, based on the pensionable years taken into account – including the pensionable years of service credited on account of the transfer; on the other hand, the minimum subsistence figure rule referred to in the fourth paragraph of Article 77 of the Staff Regulations, which guarantees a minimum amount determined solely on the basis of the years of service completed for the European Union. The pension actually awarded corresponds to the more favourable of these two results.

15. It is in this context that the issue raised by the appeal arises. Where, as in the appellant’s case, the minimum subsistence figure rule prevails, the pensionable years credited on account of the transfer do not affect the final amount of the pension. The question is whether that circumstance deprives the European Union’s retention of the transferred capital of a legal basis – an issue which the Court has already had occasion to address, in a similar case, in the judgment in KY. (4)

V. The first and second complaints in the second ground of appeal

A. Arguments of the appellant and the intervener

16. The appellant, supported by the USF/EPSU-CJ, submits, in essence, that the General Court erred in identifying Article 77 of the Staff Regulations and Article 11(2) of Annex VIII thereto as a ‘valid legal basis’ for the European Union’s enrichment. In her view, a distinction should be drawn between the formal validity of the provision relied upon and its suitability as a legal basis for the retention of capital in the specific case: a formally valid provision, in the appellant’s view, does not constitute a ‘valid legal basis’ where its application renders the staff member’s right of transfer ineffective.

17. The USF/EPSU-CJ adds, in this regard, that the EU legislature did not provide for any hierarchy between the standard calculation and the minimum subsistence figure rule, nor for any interaction between the application of the latter and the transfer mechanism. That regulatory gap in itself is argued to constitute ‘the “absence of a legal basis” required by the case-law’ on the subject of unjust enrichment.

18. The Commission, supported by the Council, contests these arguments, referring, in particular, to the judgment in KY, which is said to concern a similar factual situation.

B. Analysis

19. The following analysis proceeds in four stages. I shall first set out the conditions to which the case-law subjects an action for unjust enrichment, in order to limit the dispute to the first of these. I shall then examine the concept of ‘valid legal basis’, to show that the dichotomy between the validity and suitability of the legal basis, as proposed by the appellant, cannot be accepted. I shall then verify, in the light of the judgment in KY, that the pensionable years credited on account of the transfer were taken into account in the calculation of the pension, albeit without affecting its final amount. Finally, I shall show that none of the three precedents relied on by the appellant – the judgments in Kristensen, (5) in Barroso Truta (6) and in ABLV Bank (7) – leads to a different conclusion. Accordingly, paragraph 46 of the judgment under appeal will be shown as to be upheld.

20. According to settled case-law, for an action for restitution based on unjust enrichment on the part of the European Union to be upheld, it is necessary to prove, on the one hand, that the European Union (8) has been enriched without a valid legal basis and, on the other hand, that the applicant has suffered a corresponding impoverishment linked to that enrichment. (9)

21. Such an action does not, however, require proof of unlawfulness or fault on the part of the defendant. (10)

22. The dispute at hand concerns the first of the two cumulative conditions, namely the absence of a valid legal basis for the European Union’s enrichment. The scope of that concept is not without difficulty and requires a detailed analysis.

23. The distinction proposed by the appellant and the USF/EPSU-CJ – between the formal validity of the provision relied upon and its actual capacity to justify the retention of the transferred capital – is not, as such, supported by the Court’s case-law. It does, however, recognise a valid point: the legal basis for enrichment must be assessed in relation to the specific financial benefit at issue, and not inferred from a mere abstract reference to a provision applicable to the matter. (11) In this regard, the concept of a ‘valid legal basis’ does not refer solely to the abstract validity of the provision relied upon, but to the legal title which enables the European Union to retain the financial advantage at issue. It is precisely this assessment which, in the case at hand, leads – as I shall explain – to the rejection of the complaint.

24. In the judgment in Masdar, the Court had already made it clear that enrichment cannot be characterised as ‘unjust’ where it is justified by obligations – notably of a contractual nature – that are binding on the parties. (12) Similarly, where the enrichment is justified by the applicable legal framework – which is correctly applied and functionally suitable for justifying the retention of the disputed financial advantage – it cannot be characterised as ‘unjust’.

25. The appellant’s argument, and in particular the dichotomy between validity and suitability that it proposes, would in reality amount to making the existence of a ‘valid legal basis’ dependent not on the validity of the legal basis for the enrichment, but on the practical effect actually produced, in the case of the individual staff member, by the application of that basis. The same provision would constitute a ‘valid legal basis’ for officials whose pension is calculated under the standard calculation, whilst ceasing to be so for those to whom the minimum subsistence figure rule applies. Such a variable interpretation of the legal basis concept is incompatible with the requirement of legal certainty. Indeed, the validity of the legal basis could no longer be ascertained ex ante, in the light of the applicable regulatory framework, but only ex post, depending on the accounting outcome of the liquidation in each individual case: the same provision would constitute a legal basis suitable or unsuitable for justifying the retention of the capital depending on how, for each staff member, the comparison between the two calculations is resolved. Neither the administration nor the staff member would be able to ascertain in advance the legal regime governing the transaction. Above all, the concept of a legal basis would be stripped of its function, which is to distinguish an action for restitution from a review of lawfulness: to accept that a provision validly applied ceases to constitute a legal basis when its outcome does not satisfy the party concerned is tantamount to reintroducing, under the guise of unjust enrichment, a challenge to the provision, which is properly addressed through other remedies.

26. Whilst, on a conceptual level, the proposed dichotomy cannot therefore be accepted, it remains to be asked whether, in substantive terms, it does not identify a genuine flaw in the system. The appellant’s argument ultimately rests on the implicit premiss that the capital transferred to the PSEUI ‘must’ result in a corresponding increase in the pension, so that, in the absence of such an increase, there is no justification for retaining the capital. It is precisely this premiss that the Court, in the judgment in KY, expressly rejected. (13)

27. The clarification provided by the Court in this regard is worth recalling. The option to transfer national pension rights, provided for in Article 11(2) of Annex VIII to the Staff Regulations, offers the official concerned the guarantee that those rights will be taken into account in the calculation of his or her EU pension, but does not confer any guarantee that taking those rights into account will result in an increase in his or her pension corresponding in full to the transferred capital. (14)

28. The argument put forward by the USF/EPSU-CJ concerning the alleged absence of a hierarchy between the standard calculation and the minimum subsistence figure rule merits separate consideration. It follows from the judgment in KY that the retirement pension is calculated, in accordance with the first paragraph of Article 77 of the Staff Regulations, read in conjunction with Article 2 of Annex VIII thereto, on the basis of the years of service completed by the official. The minimum subsistence figure rule laid down in the fourth paragraph of that article applies only on a subsidiary basis, that is to say, where the application of the standard calculation does not enable the official to reach the amount guaranteed by that rule. (15)

29. This subsidiary nature does not amount to a marginalisation of the minimum subsistence figure rule, nor is it merely a matter of terminology. This reflects a structural fact: neither of the two methods of calculation operates in isolation. Only by carrying out the dual calculation provided for in Article 77 of the Staff Regulations is it possible to verify whether the amount of the pension resulting from the first calculation reaches or exceeds that derived from the minimum subsistence figure rule. (16)

30. In the case at hand, that dual calculation was carried out. Both Article 77 of the Staff Regulations and Article 11(2) of Annex VIII thereto were applied, and the credited pensionable years were ‘taken into account’, within the meaning of the judgment in KY, in the standard calculation. As is clear from paragraph 69 of the judgment in KY, this formula does not require that the credited pensionable years affect the final amount actually awarded; it merely requires that they be effectively included in the standard calculation of the pension, which constitutes the first element of the comparison with the minimum subsistence figure rule. The fact that the result of that calculation did not exceed the minimum subsistence figure does not therefore mean that there was a failure to take that into account, but instead stems from the application of the safeguard clause represented by that minimum subsistence figure rule itself.

31. Contrary to what the USF/EPSU-CJ maintains, there is no ‘omission’ on the part of the legislator regarding the relationship between the transfer and the minimum subsistence figure rule. The rule is clear: the two calculations are carried out, the more favourable result prevails, and there is no provision for the reimbursement of the transferred capital where that capital does not result in a concrete increase in the pension. Far from constituting a shortcoming in the system, this arrangement is consistent with the principle of solidarity underlying the PSEUI and does not, in itself, constitute grounds for finding a lack of a valid legal basis relevant for an action for restitution. (17)

32. Moreover, the PSEUI is not designed in such a way that the pension received constitutes the exact equivalent of the contributions paid. Once transferred, the capital representing national pension entitlements is merged with the contributions paid directly to the PSEUI: the official or staff member ceases to be the ‘holder’ of those entitlements. (18)

33. Finally, I must address the argument put forward by the USF/EPSU-CJ that the transfer is ‘supposed to be neutral’ – a phrase which the intervener attributes to an internal Commission communication from 2015 – in the sense that it should entail neither financial loss nor gain for the parties involved. Even if we accept that this communication was indeed issued in the terms stated, the argument rests, it seems to me, on an extension of the concept of neutrality that goes beyond what is provided for in the Staff Regulations. Neutrality, in the context of the transfer of pension rights, has a specific meaning: it refers to the actuarial equivalence of the conversion operation, in the sense that the capital paid in is converted into a number of pensionable years whose value, calculated according to predetermined actuarial criteria – the age of the person concerned, the demographic and financial parameters set by the GIP – corresponds to that capital. In other words, the transfer must neither systematically enrich nor impoverish any of the parties at the time it takes place: it is in this conversion, and in it alone, that the neutrality of the mechanism is expressed. It does not, however, guarantee that the final result of the settlement corresponds to the transferred capital. Such a guarantee falls outside the scope of Article 11(2) of Annex VIII to the Staff Regulations and, as I have already noted, is expressly excluded by the judgment in KY.

1. The difference from the judgment in Kristensen

34. The appellant and the USF/EPSU-CJ refer to the judgment in Kristensen. (19) I deem that this precedent cannot be applied to the case at hand, for a reason which I should set out straight away: the Kristensen case concerns a surplus of capital which arose at the time of transfer, as a result of the cap on the number of qualifying pensionable years – a surplus which the system now reimburses, and which has in fact been reimbursed to the applicant – whereas the case at hand concerns the ineffectiveness, at the time of settlement, of the pensionable years that had been validly credited. It is the Court itself, as I shall explain, which has drawn this distinction. In that case, the general implementing provisions adopted by the Council limited the number of qualifying pensionable years to the number of years during which the person concerned had been affiliated to social security schemes prior to taking up employment in the European Union, and the General Court confirmed their lawfulness. Where such a restriction applies, the portion of the transferred capital that exceeds the amount corresponding to the qualifying pensionable years that may be credited remains ‘technically’ unused: this is the excess amount which Article 7(6) of the currently applicable GIPs provide must be reimbursed to the staff member, and from which the appellant has in fact already benefited in the amount of EUR 24 805.75. This is, in any event, a matter relating to the time of the transfer and the determination of the qualifying pensionable years.

35. The distinction between this case and the situation where validly credited pensionable years are effectively rendered inoperative as a result of the application of the minimum subsistence figure rule was recently confirmed by the Court in the judgment in Bopuis, (20) which reiterated that the judgment in Kristensen concerns ‘a different issue’ from that which arises when the transferred pension rights have actually been taken into account in the calculation of the pension. This is precisely the case of the appellant, whose situation, far from coinciding with that in the Kristensen case, is instead one in which the court has already answered in the negative, in the judgment in KY.

2. The difference from the judgment in Barroso Truta

36. Nor does the reference to the judgment in Barroso Truta, (21) which the appellant reiterates in her appeal, seem relevant to me. That judgment concerned a claim for compensation for the damage arising from an alleged failure to provide information, and not an action for unjust enrichment. The General Court had dismissed the main claim on the grounds that there was no actual and certain damage at the time of the judgment. The observation in paragraph 106 of that judgment, to the effect that a refusal to return capital not taken into account at the time of liquidation could lead to unjust enrichment, was made in passing and in particularly cautious terms. (22)

37. It should be emphasised, however, that the General Court itself, in the judgment in Barroso Truta, clarified that the transferred capital ‘has not disappeared’, but has been converted into additional pensionable years which, in principle, must be taken into account when calculating the applicants’ pension entitlements; consequently, the transferred entitlements cannot be regarded as having been transferred purely at a loss. (23) Two consequences follow from this clarification. First, if the transferred capital is not lost but converted into pensionable years – which, in principle, are to be taken into account – the scenario of appropriation without consideration referred to in paragraph 106 represents an exceptional circumstance, not the normal functioning of the system; that observation cannot therefore be elevated to a general principle applicable to every case in which the credit of those pensionable years remains economically ineffective. Second, the remedies envisaged therein concerned challenges to the settlement decisions, not the restitution remedy sought in this case. A general rule of the kind sought by the applicant – according to whom the retention of the capital which remained ineffective gives rise in any case to unjust enrichment – would, moreover, be incompatible with the subsequent judgment in KY.

3. The reference to the judgment in ABLV Bank

38. Finally, the applicant invokes the judgment in ABLV Bank, according to which enrichment cannot be ruled out ‘merely because the initial justification for the payment had been established, without taking into account the existence of a legal basis for retaining the amounts in question’. (24) That reference does not appear to me to be relevant. The judgment in ABLV Bank concerns the resolution procedure for credit institutions and forms part of a regulatory context that is radically different from that of the PSEUI. Above all, the principle set out in that judgment does not undermine the criteria of the judgment in KY, which specifically concerns the matter at hand. In the case at hand, a legal basis for retaining the transferred capital exists not only at the time of the transfer – when the capital was converted into pensionable years pursuant to Article 11(2) of Annex VIII to the Staff Regulations – but continued to apply at the time of settlement, since the pensionable years thus credited were taken into account in the dual calculation provided for in Article 77 of the Staff Regulations, albeit without taking precedence over the minimum subsistence figure rule.

39. In the light of the foregoing, I deem that the General Court did not err in law in concluding, in paragraph 46 of the judgment under appeal, that the applicant’s pension was calculated in accordance with the applicable provisions, so that the first condition for unjust enrichment was not satisfied.

40. It is recognised that, in cases where the minimum subsistence figure rule takes precedence over the ordinary calculation, the outcome of the statutory mechanism may appear unsatisfactory from the perspective of the individual staff member whose transferred pension rights prove to be economically ineffective. For the reasons set out above, however, such an outcome does not constitute a lack of a valid legal basis within the meaning of the Masdar and KY case-law; any assessment of the appropriateness of corrective measures relates to regulatory choices that fall outside the scope of the Court’s judicial function.

41. I therefore suggest that the Court dismiss the first and second complaints of the second ground of appeal as unfounded.

VI. On the fourth complaint of the second ground of appeal

A. Arguments of the appellant

42. In the fourth complaint of the second ground of appeal, which is divided into two distinct parts, the appellant alleges a breach of the principle of equal treatment. Firstly, she complains that she was treated in the same way as officials and other staff members who, whilst benefiting from the minimum subsistence figure rule, did not transfer their pension rights to the PSEUI, and who therefore retained their national pension rights. Secondly, she complains that she was not treated in the same way by the authority empowered to conclude contracts of employment (‘the AECE’) of the Court of Justice as the applicants in the Barroso Truta case, some of whom are said to have been reimbursed the capital they had transferred.

B. Analysis

43. I shall examine the two parts of the argument in the order in which they have been raised. As for the first part, I will show that the declaration of ineffectiveness made by the General Court is consistent with the case-law and that, in any event, the situations being compared are not comparable. As for the second part, three independent and cumulative reasons require its rejection: the question of the scope of the decision of the Complaints Committee of the Court of Justice of the European Union in relation to the contested judgment falls within the scope of the parallel proceedings in Case C‑836/24 P; from the perspective of the case at hand, the argument is ineffective; in any event, measures adopted by one institution are not binding on the others.

1. The first part

44. With the first part, the applicant claims that she was treated in the same way as officials and other staff members who, whilst benefiting from the minimum subsistence figure rule, did not transfer their pension rights to the PSEUI. According to the applicant, these individuals are in a situation comparable to her own, but more favourable: they receive the same pension and, in addition, retain their entitlement to national pension rights.

45. The General Court, in paragraph 50 of the judgment under appeal, held that that argument was ineffective, noting – by analogy with the judgment in KY (25) – that, even if a breach of the principle of equal treatment were established, it would not affect the assessment of the two conditions to be met for a claim for unjust enrichment.

46. That approach seems correct to me. The applicant objects that, in the case at hand, the argument was put forward differently: she states that she does rely not on a separate unlawfulness, but rather on the very absence of a valid legal basis, which is intrinsically linked to the alleged unequal treatment. However, this objection cannot be upheld. As I explained in the previous section, the first condition for unjust enrichment is not, in any event, met: any argument capable of substantiating the existence of that condition, including one based on equal treatment, is bound, from that perspective, to be ineffective.

47. I add that, in any event, the situations which the applicant seeks to compare are not comparable. According to settled case-law, the comparability of situations must be assessed in the light of all the elements which characterise them, and in particular the subject matter and purpose of the act that makes the distinction. (26)

48. The applicant, exercising the right conferred by Article 11(2) of Annex VIII to the Staff Regulations, accepted the risk inherent in the transfer. (27) Those who did not exercise this option have retained their national pension entitlements, subject to the terms of the national scheme. The difference in treatment of which the applicant complains does not therefore reflect a disparity in the application of the law to comparable situations, but rather the different legal consequence of a choice for which each individual is responsible. I therefore suggest that the Court dismiss the first part of the fourth complaint of the second ground of appeal as unfounded.

2. The second part

49. In the second part, the appellant claims that she did not receive the same treatment as that accorded by the AECE of the Court of Justice to the appellants in the Barroso Truta case, some of whom, following that judgment, were reportedly reimbursed for the capital transferred to the PSEUI which had not been taken into account at the time of the calculation of their pension entitlements. In this regard, she has produced, as an annex to the appeal, the decision of the Complaints Committee of the Court of Justice of the European Union, (28) by which the AECE’s rejection of a further former applicant’s claim for reimbursement in that case was annulled on the basis of the principle of equal treatment in relation to two other former applicants who had already been reimbursed.

50. This part is closely linked to the third ground of appeal raised by the appellant in the parallel appeal C‑836/24 P. In that separate case – on which I shall deliver a separate Opinion – the same decision of 29 January 2024 is relied upon and, in particular, the question of whether the General Court was required to examine in depth the analogy with the Barroso Truta case is the subject of specific consideration. It is therefore not for this Opinion to rule on that issue, which will be dealt with in its own terms in the Opinion in Case C836/24 P.

51. Confining myself to the specific perspective of the case at hand – unjust enrichment – the argument appears to me, in any event, to be ineffective. Even if it were accepted that unequal treatment in relation to the applicants in the Barroso Truta case had in fact taken place, that circumstance – applying the KY case-law mutatis mutandis – would not affect the assessment of the conditions for an action for unjust enrichment, which, as explained, are not satisfied.

52. I add that, according to case-law, measures adopted by an EU institution in favour of a particular group of persons constitute, in the absence of any legal obligation arising from the Staff Regulations, measures which cannot be relied upon to support a plea alleging a breach of the principle of equal treatment in relation to another institution. (29) The decision of the Complaints Committee of the Court of Justice of the European Union of 29 January 2024, to which the applicant refers, is precisely of that nature. It certainly confirms the existence of reimbursements following the judgment in Barroso Truta. However, before the Committee, the complainant had raised a number of pleas in law, including one of unjust enrichment by the European Union and the breach of the principle of equal treatment. The Committee upheld the complaint on the ground of equal treatment in relation to two former applicants in the Barroso Truta case who had already been reimbursed, taking into account the context arising from paragraphs 104 to 106 of that judgment. It did not, however, base its decision on an independent finding of unjust enrichment, nor did it identify a general legal basis for the reimbursement. Given the current case-law, this argument could not, in any event, prevail over the reasons set out thus far. I therefore propose that the Court also dismiss the second part of the fourth complaint of the second ground of appeal as unfounded.

VII. Conclusion

53. In the light of all the foregoing considerations, and without prejudice to the assessments relating to the other grounds and objections in the appeal, I propose that the Court dismiss the first, second and fourth complaints of the second ground of appeal as unfounded.

1 Original language: Italian.

2 Judgment of 25 September 2024, PT v Commission (T‑788/22, ‘the judgment under appeal’, EU:T:2024:655).

3 For the parallel case concerning the plea of illegality of the fourth paragraph of Article 77 of the Staff Regulations, see the judgment of 25 September 2024, PT v Commission (T‑367/22, EU:T:2024:654), which is under appeal in Case C‑836/24 P.

4 Judgment of 4 May 2023, KY v Court of Justice of the European Union (C‑100/22 P, ‘the judgment in KY’, EU:C:2023:377).

5 Judgment of 10 November 1999, Kristensen and Others v Council (T‑103/98, T‑104/98, T‑107/98, T‑113/98 and T‑118/98, ‘the judgment in Kristensen’, EU:T:1999:289).

6 Judgment of 18 September 2018, Barroso Truta and Others v Court of Justice of the European Union (T‑702/16 P, ‘the judgment in Barroso Truta’, EU:T:2018:557).

7 Judgment of 29 September 2022, ABLV Bank v SRB (C‑202/21 P, ‘the judgment in ABLV Bank’, EU:C:2022:734, paragraph 100).

8 See the judgment of 16 December 2008, Masdar (UK) v Commission (C‑47/07 P, ‘the judgment in Masdar’, EU:C:2008:726, paragraphs 44 and 47).

9 The judgment in KY, paragraph 41.

10 The judgment in Masdar, paragraph 45; see also the judgment in KY, paragraph 42.

11 In the legal literature, on the central importance of assessing the legal basis in unjust enrichment actions, see Portonera, G., Unjust Enrichment and European Law: Present State and Future Directions, GPR, 2023.

12 The judgment in Masdar, paragraph 46.

13 The judgment in KY, paragraphs 63 and 64.

14 Ibid., paragraph 69.

15 The judgment in KY, paragraph 65.

16 Ibid., paragraph 71.

17 See, in this regard, the judgment of 9 November 2022, WP and Others v Commission (T‑604/21, EU:T:2022:686, paragraph 55).

18 Judgment of 6 September 2023, OR and OS v Commission (T‑171/22, EU:T:2023:520, paragraph 47).

19 The judgment in Kristensen.

20 See, to that effect, the judgment of 18 December 2025, Bopuis (C‑776/24, EU:C:2025:1010, paragraph 54).

21 The judgment in Barroso Truta.

22 The judgment in KY, paragraph 81. See, to the same effect, judgment of 9 November 2022, WP and Others v Commission (T‑604/21, EU:T:2022:686, paragraph 56).

23 The judgment in Barroso Truta, paragraph 103.

24 The judgment in ABLV Bank, paragraph 100.

25 See, by analogy, the judgment in KY, paragraphs 43 and 45.

26 See, to that effect, the judgment of 14 July 2022, Commission v VW and Others, (C‑116/21 P to C‑118/21 P, C‑138/21 P and C‑139/21 P, EU:C:2022:557, paragraphs 95 and 96).

27 See, to that effect, the judgment of 13 October 2015, Commission v Verile and Gjergji (T‑104/14 P, EU:T:2015:776, paragraph 83).

28 Decision of the Complaints Committee of the Court of Justice of the European Union of 29 January 2024 (R-12/23; Annex A.3 to the appeal).

29 See, to that effect, the judgment of 25 September 2024, PT v Commission (T‑367/22, EU:T:2024:654, paragraph 57 and the case-law cited therein).

Opinion of Advocate General Biondi delivered on 10 September 2026.###

Gesamter Gesetzestext

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