Judgment of the Court (First Chamber) of 21 May 2026.#BD v Sociálna poisťovňa, ústredie.#Request for a preliminary ruling from the Najvyšší správny súd Slovenskej republiky.#Reference for a preliminary ruling – Social security – Regulation (EC) No 883/2004 – Coordination of social security systems – Retirement pensions – Article 51(1) – Periods of insurance completed in a specific activity as an employed or self-employed person or in an occupation which is subject to a special scheme – Concept of ‘special scheme’ – Rules for aggregating periods of insurance – National legislation which treats workers coming within certain categories more favourably – Articles 45 and 48 TFEU – Free movement of workers.#Case C-717/24.

Provisional text

JUDGMENT OF THE COURT (First Chamber)

21 May 2026 (*)

( Reference for a preliminary ruling – Social security – Regulation (EC) No 883/2004 – Coordination of social security systems – Retirement pensions – Article 51(1) – Periods of insurance completed in a specific activity as an employed or self-employed person or in an occupation which is subject to a special scheme – Concept of ‘special scheme’ – Rules for aggregating periods of insurance – National legislation which treats workers coming within certain categories more favourably – Articles 45 and 48 TFEU – Free movement of workers )

In Case C‑717/24,

REQUEST for a preliminary ruling under Article 267 TFEU from the Najvyšší správny súd Slovenskej republiky (Supreme Administrative Court of the Slovak Republic), made by decision of 15 August 2024, received at the Court on 21 October 2024, in the proceedings

BD

v

Sociálna poisťovňa, ústredie,

THE COURT (First Chamber),

composed of F. Biltgen, President of the Chamber, I. Ziemele, A. Kumin, S. Gervasoni (Rapporteur) and M. Bošnjak, Judges,

Advocate General: D. Spielmann,

Registrar: A. Calot Escobar,

having regard to the written procedure,

after considering the observations submitted on behalf of:

–        the Italian Government, by S. Fiorentino, acting as Agent, and by P. Garofoli, avvocato dello Stato,

–        the Polish Government, by B. Majczyna and D. Lutostańska, acting as Agents,

–        the European Commission, by B.‑R. Killmann and A. Tokár, acting as Agents,

after hearing the Opinion of the Advocate General at the sitting on 18 December 2025,

gives the following

Judgment

1        This request for a preliminary ruling concerns the interpretation of Article 51(1) of Regulation (EC) No 883/2004 of the European Parliament and of the Council of 29 April 2004 on the coordination of social security systems (OJ 2004 L 166, p. 1, and corrigendum OJ 2004 L 200, p. 1) (‘Regulation No 883/2004’).

2        The request has been made in proceedings between B.D. and the Sociálna poisťovňa, ústredie (Social Insurance Fund, Central Administration, Slovakia) concerning the latter’s rejection of B.D.’s application for the granting of a retirement pension from the age of 55 in respect of the work he performed as an underground miner.

 Legal context

 European Union law

 Regulation No 1408/71

3        Article 45(2) of Regulation (EEC) No 1408/71 of the Council of 14 June 1971 on the application of social security schemes to employed persons, to self-employed persons and to members of their families moving within the Community, in the version amended and updated by Regulation (EC) No 118/97 of the Council of 2 December 1996 (OJ 1997 L 28, p. 1) (‘Regulation No 1408/71’) provided:

‘Where the legislation of a Member State makes the granting of certain benefits conditional upon the insurance periods having been completed only in an occupation which is subject to a special scheme for employed persons or, where appropriate, in a specific employment, periods completed under the legislation of other Member States shall be taken into account for the granting of these benefits only if completed under a corresponding scheme or, failing that, in the same occupation or, where appropriate, in the same employment. If, account having been taken of the periods thus completed, the person concerned does not satisfy the conditions for receipt of these benefits, these periods shall be taken into account for the granting of the benefits under the general scheme or, failing that, under the scheme applicable to manual or clerical workers, as the case may be, subject to the condition that the person has been affiliated to one or other of these schemes.’

 Regulation No 883/2004

4        Recitals 1, 4 and 13 of Regulation No 883/2004 provide:

‘(1)      The rules for coordination of national social security systems fall within the framework of free movement of persons and should contribute towards improving their standard of living and conditions of employment.

…

(4)      It is necessary to respect the special characteristics of national social security legislation and to draw up only a system of coordination.

…

(13)      The coordination rules must guarantee that persons moving within the Community and their dependants and survivors retain the rights and the advantages acquired and in the course of being acquired.’

5        As set out in Article 5 of that regulation, headed ‘Equal treatment of benefits, income, facts or events’:

‘Unless otherwise provided for by this Regulation and in the light of the special implementing provisions laid down, the following shall apply:

(a)      where, under the legislation of the competent Member State, the receipt of social security benefits and other income has certain legal effects, the relevant provisions of that legislation shall also apply to the receipt of equivalent benefits acquired under the legislation of another Member State or to income acquired in another Member State;

(b)      where, under the legislation of the competent Member State, legal effects are attributed to the occurrence of certain facts or events, that Member State shall take account of like facts or events occurring in any Member State as though they had taken place in its own territory.’

6        Article 6 of that regulation, headed ‘Aggregation of periods’, is worded as follows:

‘Unless otherwise provided for by this Regulation, the competent institution of a Member State whose legislation makes:

–      the acquisition, retention, duration or recovery of the right to benefits,

…

conditional upon the completion of periods of insurance, employment, self-employment or residence shall, to the extent necessary, take into account periods of insurance, employment, self-employment or residence completed under the legislation of any other Member State as though they were periods completed under the legislation which it applies.’

7        Article 51 of that regulation, headed ‘Special provisions on aggregation of periods’, provides, in paragraph 1:

‘Where the legislation of a Member State makes the granting of certain benefits conditional upon the periods of insurance having been completed only in a specific activity as an employed or self-employed person or in an occupation which is subject to a special scheme for employed or self-employed persons, the competent institution of that Member State shall take into account periods completed under the legislation of other Member States only if completed under a corresponding scheme or, failing that, in the same occupation, or where appropriate, in the same activity as an employed or self-employed person.

If, account having been taken of the periods thus completed, the person concerned does not satisfy the conditions for receipt of the benefits of a special scheme, these periods shall be taken into account for the purposes of providing the benefits of the general scheme or, failing that, of the scheme applicable to manual or clerical workers, as the case may be, provided that the person concerned had been affiliated to one or other of those schemes.’

8        Article 87 Regulation No 883/2004, headed ‘Transitional provisions’, provides, in paragraph 2:

‘Any period of insurance and, where appropriate, any period of employment, self-employment or residence completed under the legislation of a Member State prior to the date of application of this Regulation in the Member State concerned shall be taken into consideration for the determination of rights acquired under this Regulation.’

 Czechoslovak law

9        Paragraph 1 of zákon č. 100/1988 Zb. o sociálnom zabezpečení (Law No 100/1988 on social security) of 16 June 1988, headed ‘Basic principles’, provided, in the version applicable between 1 October 1988 and 31 May 1992:

‘…

(2)      Every citizen shall have the right to social security under this Law. The State shall provide social security benefits and services.

…

(4)      The amount of pension benefits shall depend primarily on … the length of employment … and the category of work performed.’

10      Paragraph 14 of Law No 100/1988, in the version applicable between 1 October 1988 and 31 May 1992, provided:

‘(1)      For pension purposes, jobs shall be divided into three categories according to the type of work performed.

(2)      Category I shall include jobs where predominantly hazardous activities are performed continuously and within a calendar month, where there is frequent and permanent deterioration of workers’ health due to exposure to harmful physical and chemical agents, including

(a)      mining jobs with a permanent underground workplace in deep mines,

(b)      other types of mining jobs where work is performed underground in deep mines, …

…

(4)      Occupational category III shall include jobs which are not classified under categories I or II.’

11      Paragraph 21 of Law No 100/1988, in the version applicable between 1 October 1988 and 31 May 1992, headed ‘Conditions conferring entitlement to a retirement pension’, provided, in paragraph 1:

‘A citizen shall be entitled to a retirement pension if he or she has been employed for at least 25 years and has attained the age of at least

(a)      55, provided that he or she has been employed for at least 15 years in an occupation referred to in Paragraph 14(2)(a) …

(c)      55, provided that he or she has been employed for at least 20 years in an occupation referred to in Paragraph 14(2)(b) to (h),

(d)      58, provided that he or she has been employed for at least 20 years in an occupation referred to in Paragraph 14(2)(i) to (l), or

(e)      60.’

12      Law No 100/1988 was amended by zákon č. 235/1992 Zb. o zrušení pracovných kategórií (Law No 235/1992 abolishing employment categories) of 28 April 1992, which entered into force on 1 June 1992.

13      Paragraph 14(1) of Law No 100/1988, in the version thereof as amended by Law No 235/1992, provided:

‘For pension insurance purposes, until 31 December 1992, jobs shall be classified into three categories depending on the type of work performed. Jobs under categories I and II shall be set out in the sectoral lists of occupations classified under categories I and II published before 1 June 1992; jobs not classified under categories I or II shall be included in category III.’

14      Paragraph 15 of Law No 100/1988, as amended by Law No 235/1992, provided:

‘For pension insurance purposes, jobs engaged in after 31 December 1992 shall be regarded as jobs falling within category III.’

15      As set out in Paragraph 175 of Law No 100/1988, as amended by Law No 235/1992:

‘Entitlements arising from the classification of jobs under categories I and II or of services in categories I and II shall be taken into account until 31 December 2016.’

 Slovak law

16      Law No 100/1988 was repealed by zákon č. 461/2003 Z. z. o sociálnom poistení (Law No 461/2003 on social insurance) of 30 October 2003, which, in the version applicable to the dispute in the main proceedings (‘Law No 461/2003’), provides, in Paragraph 1, headed ‘Subject matter and scope of the Law’:

‘(1)      This Law defines social insurance [and] lays down the scope of social insurance …

…

(3)      This Law shall not apply to officers of the Police Corps, the Slovak Information Service, the National Security Office, the Judiciary Guards and Prison Wardens Corps, the Fire and Rescue Corps, the Mountain Rescue Service, armed officers of the Financial Administration …, professional soldiers of the armed forces, soldiers in special service …, whose social insurance is governed by separate provisions …’

17      Paragraph 65 of Law No 461/2003, headed ‘Eligibility criteria for retirement pensions’, is worded as follows:

‘(1)      Insured persons shall be entitled to a retirement pension if they have paid pension contributions for at least 15 years and have reached retirement age.

(2)      The retirement age of insured persons shall be determined in accordance with Annex 3a, subject to Paragraph 274 of this Law …’

18      As set out in Paragraph 112 of Law No 461/2003, headed ‘Changes in entitlement to benefit, changes in entitlement to payment of benefit and changes in amount of benefit’:

‘(1)      The benefit shall be granted … from the date on which the benefit … is payable, … up to a maximum of three years back from the date of the application for the benefit …, if it is established retroactively that the benefit …

(d)      was granted from a date later than that from which it is payable.’

19      Paragraph 274 of that law provides:

‘(1)      Entitlements arising from the classification of jobs under categories I and II shall be maintained.

…’

 The dispute in the main proceedings and the questions referred for a preliminary ruling

20      The applicant in the main proceedings worked from 1 July 1976 to 31 August 1995 as a miner in an underground mine in Karviná, in the territory of the present-day Czech Republic. He subsequently held various other jobs in the Czech Republic and then in Slovakia.

21      Under the legislation of the Czechoslovak federation, jobs were classified into three categories, depending on their degree of risk and arduousness. Under that system, work as a miner came within category I, which conferred entitlement to a retirement pension from the age of 55, provided that the person concerned had worked for 25 years, including 15 years underground in a deep mine.

22      In 1992, the Czechoslovak federation adopted new legislation providing for the abolition of the various employment categories with effect from 31 December 1992, with all jobs to come within the rules applicable to category III as of that date. Entitlements arising from employment in categories I or II until 31 December 1992 were preserved until 31 December 2016.

23      On 31 December 1992, the Czechoslovak federation ceased to exist and was succeeded by two independent States. In the Czech Republic, the various employment categories were abolished on that date. In Slovakia, however, that abolition was deferred until 31 December 1999.

24      In 2013, after receiving a retirement pension from the social security authorities in the Czech Republic under the legislation of that Member State, the applicant in the main proceedings, who was then aged 55, applied for the grant of his retirement pension in Slovakia. However, that application was rejected by the defendant in the main proceedings on the ground that he had not reached the age required to receive such a pension.

25      The applicant in the main proceedings was ultimately granted entitlement to a retirement pension with effect from 2 October 2020, the date on which he had reached the age of 62 years and 8 months. However, the defendant in the main proceedings maintained that he was not entitled to a retirement pension granted under more favourable conditions to persons who had worked as underground miners for a period of 15 years. In that regard, it took the view that, since the applicant in the main proceedings had performed such work in the territory of the present-day Czech Republic, he was entitled to a retirement pension from the age of 55 only if he could demonstrate that, for a period of 15 years, he had held a job coming within category I under the legislation of that Member State. However, according to the defendant in the main proceedings, on 31 December 1992, the date on which the employment categories were abolished in the Czech Republic, the applicant in the main proceedings had worked as an underground miner for only slightly more than 14 years.

26      That gave rise to proceedings in which the applicant in the main proceedings argued that, in order to determine whether the condition relating to the pursuit of an activity for a period of 15 years was satisfied, the defendant in the main proceedings was required to take into account, as a period of employment in a job coming within category I, the period from 1 January 1993 to 31 August 1995 during which he had continued to work as an underground miner in the Czech Republic, despite the abolition of employment categories in that Member State with effect from 31 December 1992.

27      Hearing an appeal brought by the applicant in the main proceedings, the Najvyšší správny súd Slovenskej republiky (Supreme Administrative Court of the Slovak Republic), which is the referring court, seeks clarification as to the interpretation of Article 51(1) of Regulation No 883/2004 relating to the aggregation of periods for the purpose of calculating a retirement pension where the Member State competent for granting that pension has established a special social security scheme or where that Member State, without having established such a special scheme, applies specific rules to certain activities.

28      That court harbours reservations owing, in particular, to the differences in wording between the various language versions of that provision. According to the referring court, two literal interpretations of that provision are conceivable. According to a first interpretation, which appears to be supported by, inter alia, the Slovak-, English-, French- and Polish-language versions of that provision, that provision would apply not only where the legislation of the competent Member State for the purpose of granting pension benefits establishes a special social security scheme, but also, more broadly, where, as is the legal situation in Slovakia, that legislation links certain special advantages to the performance of a particular activity. By contrast, according to a second interpretation, corresponding to the Czech- and German-language versions of that provision, that provision would apply only where a special scheme distinct from the general scheme exists in the Member State competent for granting pension benefits.

29      The referring court points out, referring to recitals 1 and 13 of Regulation No 883/2004, that if that second interpretation were adopted, it could result in an obstacle to the free movement of workers, in so far as the rights and advantages acquired or in the course of being acquired by such workers would not be guaranteed. A worker performing a specific activity in one Member State and receiving, under the legislation of that State, certain advantages linked to that activity under the general scheme, without, however, being covered by a distinct scheme, might be dissuaded from performing that activity in another Member State, since the periods of insurance completed in the performance of such an activity would not be taken into account as favourably in that other Member State.

30      Even if Article 51(1) of Regulation No 883/2004 had to be interpreted as applying only where there is a special social security scheme distinct from the general scheme, that regulation does not make it possible to clearly determine the characteristics that would enable such a scheme to be identified. It follows that there is uncertainty as to whether rules applicable in the area of retirement pensions to certain specific activities, such as those provided for by Slovak legislation, may be classified as a ‘special scheme’, within the meaning of that provision.

31      In that regard, the referring court notes that, in the present case, the national legislation at issue did not establish a separate scheme applicable only to underground miners but, on the contrary, established a social security scheme applicable to all workers. Nevertheless, that court states that, irrespective of that single scheme, the job of an underground miner as well as the other jobs coming within category I benefit from a lowering of the retirement age.

32      In those circumstances, the Najvyšší správny súd Slovenskej republiky (Supreme Administrative Court of the Slovak Republic) decided to stay the proceedings and to refer the following questions to the Court of Justice for a preliminary ruling:

‘(1)      Must Article 51(1) of Regulation [No 883/2004] be interpreted as applying to an old-age pension the decision on which was adopted by the competent institution of a Member State, … only on condition that a “special scheme for employed or self-employed persons” is established under the legislation of that Member State[?]

… If so, what characterises such a “special scheme” (for example, the fact that it is administered by a separate institution, it is financed separately, or it is intended only for a particular group of employed or self-employed persons)[?]

(2)      [Must Article 51(1) of that regulation be interpreted as applying to such a pension] also where the legislation of that Member State does not provide for such a ‘special scheme’, but merely allows a particular group of persons who have completed periods of insurance solely in the context of a specific activity (for example, miners working in deep mines) to acquire the right, on the basis of such periods, to an old-age pension under more advantageous conditions than other persons who are otherwise employed or self-employed?’

 Consideration of the questions referred

33      By its questions, which it is appropriate to examine together, the referring court asks, in essence, whether Article 51(1) of Regulation No 883/2004 must be interpreted as meaning that the specific mechanism for the aggregation of periods for which it provides applies both where the Member State competent for granting the retirement benefit has established a special social security scheme that is formally distinct from the general scheme and specific to certain occupations or activities, and where that Member State, without having established such a special scheme, reserves certain advantages, in the context of the grant of such a pension, to a defined category of persons who have completed periods of insurance in the exercise of a specific occupation or activity. If so, the referring court asks what factors make it possible to establish the existence of such a special scheme within the meaning of that provision.

34      As a preliminary point, as regards the applicability of Regulation No 883/2004 to the dispute in the main proceedings, it should be borne in mind that Article 87(2) of that regulation provides that any period of insurance, employment, self-employment or residence completed prior to the date of application of that regulation in the territory of that Member State are to be taken into consideration for the determination of rights to benefits. Consequently, the fact that the periods of contribution at issue in the main proceedings pre-date the entry into force of Regulation No 883/2004 and the accession to the European Union by the Member States concerned, namely the Slovak Republic and the Czech Republic, does not preclude the application of that regulation to a situation such as that at issue in the main proceedings (see, to that effect and by analogy, judgments of 18 April 2002, Duchon, C‑290/00, EU:C:2002:234, paragraphs 32 to 34, and of 22 January 2015, Balazs, C‑401/13, EU:C:2015:26, paragraphs 31 and 32).

35      As regards the answer to be given to the questions referred, it should be noted that the wording of the first subparagraph of Article 51(1) of Regulation No 883/2004, in the French-language version, which refers to ‘la condition que les périodes d'assurance aient été accomplies uniquement dans une activité salariée ou non salariée spécifique ou dans une occupation soumise à un régime spécial’ (conditional upon the periods of insurance having been completed only in a specific activity as an employed or self-employed person or in an occupation which is subject to a special scheme), suggests, due to the use of the singular in the expression ‘soumise à un régime spécial’, that the aggregation rule which it lays down applies either where, in the competent Member State, the occupation concerned is covered by a special social security scheme, or where the legislation of that Member State makes entitlement to certain benefits subject to the completion of periods of insurance in a specific activity as an employed or self-employed person, without that activity necessarily being covered by a special scheme. That wording corresponds, inter alia, to the Slovak-, English-, Italian-, Latvian-, Polish- and Slovenian-language versions of that provision.

36      By contrast, the wording of other language versions of that provision, in particular those in Spanish (‘sujetas a un régimen especial’), German (‘für die ein Sondersystem … gilt’) and Greek (‘για τα οποία ισχύει ειδικό σύστημα που εφαρμόζεται’), seems to indicate, owing to the use of the plural, that the application of that provision presupposes, in all cases, that, in the competent Member State, the activities and occupations in question are covered by a special scheme.

37      It is settled case-law that the wording used in one language version of a provision of EU law cannot serve as the sole basis for the interpretation of that provision, or be made to override the other language versions in that regard. Such an approach would be incompatible with the requirement for uniform application of EU law. Where there is divergence between the various language versions, the provision in question must be interpreted by reference to the purpose and general scheme of the rules of which it forms part (see, to that effect, judgments of 27 March 1990, Cricket St Thomas, C‑372/88, EU:C:1990:140, paragraphs 18 and 19, and of 20 November 2025, Lolach, C‑327/24, EU:C:2025:901, paragraph 29).

38      In view of the differences between the various language versions of the first subparagraph of Article 51(1) of Regulation No 883/2004, as noted in paragraphs 35 and 36 above, it is necessary, in interpreting that provision, in accordance with the Court’s settled case-law, to analyse the context in which it occurs and the objectives pursued by the rules of which it is part (see, to that effect, judgments of 17 November 1983, Merck, 292/82, EU:C:1983:335, paragraph 12, and of 25 February 2025, BSH Hausgeräte, C‑339/22, EU:C:2025:108, paragraph 27).

39      As regards the general scheme of the legislation of which that provision forms part, it should be noted that Article 6 of that legislation, which forms part of Title I, headed ‘General provisions’, lays down a general rule for the aggregation of periods. Under that rule and unless otherwise provided, the competent institution of a Member State whose legislation makes the acquisition of the right to benefits conditional upon the completion of periods of insurance, employment, self-employment or residence is required to take into account equivalent periods completed under the legislation of another Member State as though they were completed under the legislation which it applies.

40      That general rule on the aggregation of periods is given concrete expression and supplemented, with regard to retirement pensions, by Article 51 of Regulation No 883/2004, paragraph 1 of which guarantees, more specifically, that persons who have pursued an activity entitling them to specific advantages in relation to retirement pensions do not lose the benefit of those advantages solely because they have exercised their freedom of movement in pursuing that activity in another Member State.

41      That provision corresponds to Article 45(2) of Regulation No 1408/71, which Regulation No 883/2004 repealed and replaced in order to modernise and simplify it, whilst retaining the same objective (see, to that effect, judgment of 21 March 2018, Klein Schiphorst, C‑551/16, EU:C:2018:200, paragraph 31).

42      However, Article 45(2) of Regulation No 1408/71 did not make the mechanism for the aggregation of periods for which it provided conditional upon the existence, in the competent Member State, of a special social security scheme formally distinct from the general scheme. That article provided that where the grant of certain benefits was made conditional, by the legislation of that Member State, upon the insurance periods having been completed in an occupation subject to a special scheme or, where appropriate, in a specific employment, periods completed under the legislation of other Member States were to be taken into account for the granting of such benefits only if completed under such a scheme or, failing that, in the same occupation or, where appropriate, in the same employment.

43      Since the EU legislature did not, by adopting Article 51(1) of Regulation No 883/2004, intend to adopt a more restrictive method of aggregation, as the Advocate General observed in point 54 of his Opinion, it must be held that that provision is intended to apply whenever specific rules governing the determination of retirement pensions are laid down for certain occupations or activities in the Member State competent for granting the benefit, including where there is no special social security scheme formally distinct from the general scheme.

44      Such an interpretation cannot be called into question by the fact that the second subparagraph of Article 51(1) of that regulation refers to the situation in which, account having been taken of the periods thus completed in another Member State, the person concerned does not satisfy the conditions for receipt of the benefits ‘of a special scheme’, since that provision also provides that those periods may, failing that, be taken into account for the granting of benefits under other schemes.

45      Furthermore, as regards the objective pursued by that regulation, it should be borne in mind that, as is clear from recital 4 thereof, the aim of that regulation is not to establish a common scheme of social security, but only to ensure the coordination of the social security schemes of the Member States, while leaving Member States the power to organise their respective systems, provided that they exercise that power in accordance with EU law, in particular with the freedom given to every citizen of the European Union to move and reside within the territory of the Member States (see, to that effect and by analogy, judgments of 21 February 2013, Salgado Gonzalez, C‑282/11, EU:C:2013:86, paragraphs 35 to 37, and of 7 December 2017, Zaniewicz-Dybeck, C‑189/16, EU:C:2017:946, paragraphs 38 to 40).

46      In that regard, it is apparent from the Court’s case-law that, although EU law does not require the exercise by a worker of his or her freedom of movement to be neutral as regards social security, compatibility with Articles 45 and 48 TFEU nevertheless requires that workers from other Member States must not be placed at a disadvantage as compared with workers who pursue or have pursued all their activities in the Member State concerned (see, to that effect, judgment of 14 March 2019, Vester, C‑134/18, EU:C:2019:212, paragraphs 32 and 33).

47      From that standpoint, it is irrelevant whether the Member State competent for granting the retirement pension has established a special social security scheme which is formally distinct from the general scheme, or whether it has chosen to adopt a set of rules specific to certain activities or occupations within the general scheme. Such differences merely reflect choices relating to the organisation and financing of social security systems, which may vary considerably from one Member State to another.

48      Furthermore, an interpretation of the first subparagraph of Article 51(1) of Regulation No 883/2004 to the effect that that provision applies only to occupations and activities covered by a special social security scheme necessarily distinct from the general scheme in the Member State competent for granting the retirement pension would run counter to the objective of the free movement of workers, since it would place at a disadvantage workers who have exercised their freedom of movement while pursuing an occupation or activity conferring entitlement, in that Member State, to a retirement pension under conditions more favourable than those applicable to other workers, as compared with workers who have pursued the same activity exclusively in that Member State.

49      It follows that the first subparagraph of Article 51(1) of Regulation No 883/2004 must be interpreted as applying in all cases where the legislation of the Member State competent for granting the retirement pension lays down rules in the field of retirement pensions specific to certain occupations or activities, including where those rules do not constitute or form part of a special social security scheme formally distinct from the general scheme.

50      It should also be pointed out that, contrary to the European Commission’s contention, the completion of periods of contribution in another Member State in the exercise of a specific occupation or activity cannot be taken into account under Article 5(b) of that regulation, which provides that, where, under the legislation of the competent Member State, legal effects are attributed to the occurrence of certain facts or events, that Member State is to take account of like facts or events occurring in any Member State as though they had taken place in its own territory. It is clear from its wording that that provision concerns the taking into account, in the competent Member State, of the occurrence of specific facts or events taking place in another Member State, such as a birth, death or accident, and does not govern the aggregation of periods of contribution completed in another Member State.

51      In the present case, it is apparent from the request for a preliminary ruling that the referring court is uncertain whether the periods completed by the applicant in the main proceedings as an underground miner in the Czech Republic between 1 January 1993 and 31 August 1995 must be taken into account in the Slovak Republic, pursuant to the first subparagraph of Article 51(1) of Regulation No 883/2004, in order to assess whether the condition relating to the completion of 15 years of contributions as an underground miner, conferring entitlement to certain advantages in relation to retirement pensions in that Member State, is satisfied. In that regard, in the light of the information set out in the order for reference, it should be noted, first, that the Slovak legislation laid down, for the period concerned, rules on retirement pensions specific to the occupation of underground miner and, second, that the periods completed by the applicant in the main proceedings in the Czech Republic were completed in that occupation, with the result that it appears, subject to the checks which it is for the referring court to carry out, that those periods must be taken into consideration.

52      In the light of all of the foregoing reasons, the answer to the questions referred is that Article 51(1) of Regulation No 883/2004 must be interpreted as meaning that the specific mechanism for the aggregation of periods for which it provides applies both where the Member State competent for granting the retirement pension has established a special social security scheme that is formally distinct from the general scheme and specific to certain occupations or activities, and where that Member State, without having established such a special scheme, reserves certain advantages, in the context of the grant of such a pension, to a defined category of persons who have completed periods of insurance in the exercise of a specific occupation or activity.

 Costs

53      Since these proceedings are, for the parties to the main proceedings, a step in the action pending before the referring court, the decision on costs is a matter for that court. Costs incurred in submitting observations to the Court, other than the costs of those parties, are not recoverable.

On those grounds, the Court (First Chamber) hereby rules:

The first subparagraph of Article 51(1) of Regulation (EC) No 883/2004 of the European Parliament and of the Council of 29 April 2004 on the coordination of social security systems

must be interpreted as meaning that the specific mechanism for the aggregation of periods for which it provides applies both where the Member State competent for granting the retirement pension has established a special social security scheme that is formally distinct from the general scheme and specific to certain occupations or activities, and where that Member State, without having established such a special scheme, reserves certain advantages, in the context of the grant of such a pension, to a defined category of persons who have completed periods of insurance in the exercise of a specific occupation or activity.

[Signatures]

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*      Language of the case: Slovak.