62023CJ0743
JUDGMENT OF THE COURT (First Chamber)
11 December 2025 (
*1
) (
i
)
[Text rectified by order of 27 January 2026]
(Reference for a preliminary ruling – Agreement between the European Community and its Member States, of the one part, and the Swiss Confederation, of the other, on the free movement of persons – Migrant workers – Social security – Applicable legislation – Regulation (EC) No 883/2004 – Article 11 – Article 13(1) – Regulation (EC) No 987/2009 – Article 14(8) – Worker pursuing an activity as an employed person in the territory of several States, including a Member State, the Swiss Confederation and third countries – Concept of ‘substantial part of the activity’ – Taking account of the activity pursued in third countries)
In Case C‑743/23,
REQUEST for a preliminary ruling under Article 267 TFEU from the Landessozialgericht für das Saarland (Higher Social Court, Saarland, Germany), made by decision of 15 November 2023, received at the Court on 4 December 2023, in the proceedings
A
v
GKV-Spitzenverband,
interested party:
Moguntia Food Group AG,
THE COURT (First Chamber),
composed of F. Biltgen (Rapporteur), President of the Chamber, T. von Danwitz, Vice-President of the Court, acting as Judge of the First Chamber, I. Ziemele, A. Kumin and S. Gervasoni, Judges,
Advocate General: A. Rantos,
Registrar: D. Dittert, Head of Unit,
having regard to the written procedure and further to the hearing on 5 March 2025,
after considering the observations submitted on behalf of:
–
A, by M. Blum, Rechtsanwältin,
–
GKV-Spitzenverband, by C. Donus, acting as Agent,
–
Moguntia Food Group AG, by V. Ohlekopf and M. Schwind, Rechtsanwälte,
–
the German Government, by J. Möller and P.‑L. Krüger, acting as Agents,
–
the Belgian Government, by S. Baeyens, C. Jacob and L. Van den Broeck, acting as Agents,
–
[As rectified by order of 27 January 2026] the French Government, by B. Fodda and T. Lechevallier, acting as Agents,
–
the European Commission, by S. Delaude and B.‑R. Killmann, acting as Agents,
after hearing the Opinion of the Advocate General at the sitting on 5 June 2025,
gives the following
Judgment
1
This request for a preliminary ruling concerns the interpretation of Article 13(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), as amended by Regulation (EU) No 465/2012 of the European Parliament and of the Council of 22 May 2012 (OJ 2012 L 149, p. 4) (‘Regulation No 883/2004, as amended’), read in conjunction with Article 14(8) of Regulation (EC) No 987/2009 of the European Parliament and of the Council of 16 September 2009 laying down the procedure for implementing Regulation No 883/2004 (OJ 2009 L 284, p. 1), as amended by Regulation No 465/2012 (‘Regulation No 987/2009’).
2
The request has been made in proceedings between A and GKV-Spitzenverband (National Association of Statutory Health Insurance Funds, Germany) concerning that association’s decision to issue A with an A1 form certifying that, for the period from 1 December 2015 to 31 December 2020, he was subject to the German social security scheme.
Legal context
International law
3
On 21 June 1999, the European Community and the Swiss Confederation concluded seven agreements, including the Agreement between the European Community and its Member States, of the one part, and the Swiss Confederation, of the other, on the free movement of persons (OJ 2002 L 114, p. 6), which was amended, inter alia, by Decision No 1/2012 of the Joint Committee established under the Agreement between the European Community and its Member States, of the one part, and the Swiss Confederation, of the other, on the free movement of persons of 31 March 2012 replacing Annex II to that Agreement on the coordination of social security schemes (OJ 2012 L 103, p. 51) (‘the AFMP’).
4
Article 8 of the AFMP, entitled ‘Coordination of social security systems’, is worded as follows:
‘The Contracting Parties shall make provision, in accordance with Annex II, for the coordination of social security systems with the aim in particular of:
…
(b)
determining the legislation applicable;
…’
5
Annex II to the AFMP, entitled ‘Co-ordination of social security schemes’, provides, in Article 1 thereof:
‘1   The contracting parties agree, with regard to the coordination of social security schemes, to apply among themselves the Community acts to which reference is made, as in force at the date of signature of the Agreement and as amended by section A of this Annex, or rules equivalent to such acts.
2.   The term “Member State(s)” contained in the acts referred to in section A of this Annex shall be understood to include Switzerland in addition to the States covered by the relevant Community acts.’
6
Section A of Annex II to the AFMP, entitled ‘Acts referred to’, includes, inter alia, Regulations No 883/2004 and No 987/2009, which replaced Regulation (EEC) No 1408/71 of the Council of 14 June 1971 on the application of social security schemes to employed persons and their families moving within the Community (OJ, English Special Edition: Series I Volume 1971(II), p. 416).
European Union law
Regulation No 883/2004, as amended
7
Recitals 1, 3 and 45 of Regulation No 883/2004, as amended, state:
‘(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.
…
(3)
[Regulation No 1408/71] has been amended and updated on numerous occasions in order to take into account not only developments at Community level, including judgments of the Court of Justice, but also changes in legislation at national level. Such factors have played their part in making the Community coordination rules complex and lengthy. Replacing, while modernising and simplifying, these rules is therefore essential to achieve the aim of the free movement of persons.
…
(45)
Since the objective of the proposed action, namely the coordination measures to guarantee that the right to free movement of persons can be exercised effectively, cannot be sufficiently achieved by the Member States and can therefore, by reason of the scale and effects of that action, be better achieved at Community level, the Community may adopt measures in accordance with the principle of subsidiarity as set out in Article 5 of the Treaty. …’
8
Title II of that regulation, entitled ‘Determination of the legislation applicable’, which replaces the provisions of Title II of Regulation No 1408/71, contains Articles 11 to 16 of that regulation.
9
Article 11 of that regulation, entitled ‘General rules’, provides:
‘1.   Persons to whom this Regulation applies shall be subject to the legislation of a single Member State only. Such legislation shall be determined in accordance with this Title.
…
3.   Subject to Articles 12 to 16:
(a)
a person pursuing an activity as an employed or self-employed person in a Member State shall be subject to the legislation of that Member State;
(b)
a civil servant shall be subject to the legislation of the Member State to which the administration employing him/her is subject;
(c)
a person receiving unemployment benefits in accordance with Article 65 under the legislation of the Member State of residence shall be subject to the legislation of that Member State;
(d)
a person called up or recalled for service in the armed forces or for civilian service in a Member State shall be subject to the legislation of that Member State;
(e)
any other person to whom subparagraphs (a) to (d) do not apply shall be subject to the legislation of the Member State of residence, without prejudice to other provisions of this Regulation guaranteeing him/her benefits under the legislation of one or more other Member States.
4.   For the purposes of this Title, an activity as an employed or self-employed person normally pursued on board a vessel at sea flying the flag of a Member State shall be deemed to be an activity pursued in the said Member State. However, a person employed on board a vessel flying the flag of a Member State and remunerated for such activity by an undertaking or a person whose registered office or place of business is in another Member State shall be subject to the legislation of the latter Member State if he/she resides in that State. The undertaking or person paying the remuneration shall be considered as the employer for the purposes of the said legislation.’
10
Article 12 of that regulation, entitled ‘Special rules’, provides:
‘1.   A person who pursues an activity as an employed person in a Member State on behalf of an employer which normally carries out its activities there and who is posted by that employer to another Member State to perform work on that employer’s behalf shall continue to be subject to the legislation of the first Member State, provided that the anticipated duration of such work does not exceed 24 months and that he/she is not sent to replace another posted person.
2.   A person who normally pursues an activity as a self-employed person in a Member State who goes to pursue a similar activity in another Member State shall continue to be subject to the legislation of the first Member State, provided that the anticipated duration of such activity does not exceed 24 months.’
11
Article 13 of Regulation No 883/2004, as amended, entitled ‘Pursuit of activities in two or more Member States’, provides, in paragraphs 1 and 2 thereof:
‘1.   A person who normally pursues an activity as an employed person in two or more Member States shall be subject:
(a)
to the legislation of the Member State of residence if he/she pursues a substantial part of his/her activity in that Member State; or
(b)
if he/she does not pursue a substantial part of his/her activity in the Member State of residence:
(i)
to the legislation of the Member State in which the registered office or place of business of the undertaking or employer is situated if he/she is employed by one undertaking or employer; or
(ii)
to the legislation of the Member State in which the registered office or place of business of the undertakings or employers is situated if he/she is employed by two or more undertakings or employers which have their registered office or place of business in only one Member State; or
(iii)
to the legislation of the Member State in which the registered office or place of business of the undertaking or employer is situated other than the Member State of residence if he/she is employed by two or more undertakings or employers, which have their registered office or place of business in two Member States, one of which is the Member State of residence; or
(iv)
to the legislation of the Member State of residence if he/she is employed by two or more undertakings or employers, at least two of which have their registered office or place of business in different Member States other than the Member State of residence.
2.   A person who normally pursues an activity as a self-employed person in two or more Member States shall be subject to:
(a)
the legislation of the Member State of residence if he/she pursues a substantial part of his/her activity in that Member State;
or
(b)
the legislation of the Member State in which the centre of interest of his/her activities is situated, if he/she does not reside in one of the Member States in which he/she pursues a substantial part of his/her activity.’
12
Article 76 of that regulation, entitled ‘Cooperation’, provides, in paragraph 4 thereof:
‘The institutions and persons covered by this Regulation shall have a duty of mutual information and cooperation to ensure the correct implementation of this Regulation.
…’
Regulation No 987/2009
13
Article 14(5) to (11) of Regulation No 987/2009 provides:
‘5.   For the purposes of the application of Article 13(1) of [Regulation No 883/2004], a person who “normally pursues an activity as an employed person in two or more Member States” shall refer to a person who simultaneously, or in alternation, for the same undertaking or employer or for various undertakings or employers, exercises one or more separate activities in two or more Member States.
…
6.   For the purposes of the application of Article 13(2) of [Regulation No 883/2004], a person who “normally pursues an activity as a self-employed person in two or more Member States” shall refer, in particular, to a person who simultaneously or in alternation pursues one or more separate self-employed activities, irrespective of the nature of those activities, in two or more Member States.
7.   For the purpose of distinguishing the activities under paragraphs 5 and 6 from the situations described in Article 12(1) and (2) of [Regulation No 883/2004], the duration of the activity in one or more other Member States (whether it is permanent or of an ad hoc or temporary nature) shall be decisive. For these purposes, an overall assessment shall be made of all the relevant facts including, in particular, in the case of an employed person, the place of work as defined in the employment contract.
8.   For the purposes of the application of Article 13(1) and (2) of [Regulation No 883/2004], a “substantial part of employed or self-employed activity” pursued in a Member State shall mean a quantitatively substantial part of all the activities of the employed or self-employed person pursued there, without this necessarily being the major part of those activities.
To determine whether a substantial part of the activities is pursued in a Member State, the following indicative criteria shall be taken into account:
(a)
in the case of an employed activity, the working time and/or the remuneration; and
…
In the framework of an overall assessment, a share of less than 25% in respect of the criteria mentioned above shall be an indicator that a substantial part of the activities is not being pursued in the relevant Member State.
9.   For the purposes of the application of Article 13(2)(b) of [Regulation No 883/2004], the “centre of interest” of the activities of a self-employed person shall be determined by taking account of all the aspects of that person’s occupational activities, notably the place where the person’s fixed and permanent place of business is located, the habitual nature or the duration of the activities pursued, the number of services rendered, and the intention of the person concerned as revealed by all the circumstances.
…
11.   If a person pursues his activity as an employed person in two or more Member States on behalf of an employer established outside the territory of the Union, and if this person resides in a Member State without pursuing substantial activity there, he shall be subject to the legislation of the Member State of residence.’
14
Under Article 16(2) of Regulation No 987/2009:
‘The designated institution of the place of residence shall without delay determine the legislation applicable to the person concerned, having regard to Article 13 of [Regulation No 883/2004] and Article 14 of [Regulation No 987/2009]. …’
15
Article 19 of that regulation, entitled ‘Provision of information to persons concerned and employers’, provides, in paragraph 2 thereof:
‘At the request of the person concerned or of the employer, the competent institution of the Member State whose legislation is applicable pursuant to Title II of [Regulation No 883/2004] shall provide an attestation that such legislation is applicable and shall indicate, where appropriate, until what date and under what conditions.’
The dispute in the main proceedings and the questions referred for a preliminary ruling
16
The applicant and respondent in the main proceedings (‘the applicant in the main proceedings’), who at the time was residing in Germany, was employed full-time by Moguntia Food Group AG, a company established in Basel (Switzerland), during the period from 1 December 2015 to 31 December 2020 (‘the period at issue’).
17
It is apparent from the order for reference that he pursued that activity as an employed person simultaneously in Switzerland, for 10.5 days per quarter, in Germany, working from home for 10.5 days per quarter, and in third countries. The amount of his monthly salary did not vary depending on the location where he pursued his activity.
18
On 19 November 2015, the applicant in the main proceedings contacted GKV-Spitzenverband, which, pursuant to Article 16(2) of Regulation No 987/2009, is the designated institution of his place of residence in Germany to determine the applicable legislation when the occupational activity of the person concerned is normally pursued in two or more Member States, stating that he was working in Switzerland on behalf of Moguntia Food Group and that less than 25% of his activity was being pursued in Germany.
19
By letter of 22 February 2016, the Amt für Sozialbeiträge des Kantons Basel-Stadt (Office for Social Contributions of the Canton of Basel-Stadt, Switzerland) took note of the fact that, on 1 December 2015, the applicant in the main proceedings had taken out compulsory health insurance in Switzerland.
20
Nevertheless, after finding that the applicant in the main proceedings habitually pursued his activity as an employed person in two or more Member States and that a substantial part of that activity was pursued in Germany, where he was residing, GKV-Spitzenverband found, by decision of 18 August 2016, that, under Regulation No 883/2004, as amended, German social security legislation applied during the period at issue and, consequently, issued the applicant in the main proceedings with an A1 certificate.
21
By decision of 18 December 2020, GKV-Spitzenverband rejected the objection made by the applicant in the main proceedings against the decision of 18 August 2016 and confirmed that, in accordance with Regulations No 883/2004, as amended, and No 987/2009, that person was covered, during the period at issue, by German social security legislation. In that regard, GKV-Spitzenverband first of all recalled that, in accordance with Article 13(1) of Regulation No 883/2004, where a person pursues an occupational activity in two or more Member States, that person is to be subject to the legislation of the Member State of residence if he or she pursues a substantial part of his or her activity as an employed person in that Member State. Next, GKV-Spitzenverband stated that, under Article 14(8) of Regulation No 987/2009, a substantial part of employed or self-employed activity is to be considered to be pursued in a Member State if, when the situation of the person concerned is assessed as a whole, it is found that he or she spends at least 25% of his or her working time in the Member State in which he or she resides and/or receives at least 25% of his or her remuneration there. Taking the view that, to that end, only activities pursued in the countries coming within the territorial scope of Regulations No 883/2004 and No 987/2009 are relevant, GKV-Spitzenverband took into consideration only the working time spent by the applicant in the main proceedings in Germany and in Switzerland and concluded that 50% of his working time was spent in Germany, which is his State of residence, that share representing a substantial part of his employed activity.
22
On 28 December 2020, the applicant in the main proceedings brought an action against that decision before the Sozialgericht (Social Court, Germany), claiming that, for the purpose of determining the social security legislation applicable during the period at issue, account should be taken not only of the periods of activity he had completed in Germany and in Switzerland, but also of those which he had spent in third countries and that, in any event, he was already covered, during the period at issue, by the Swiss social security scheme.
23
By judgment of 4 August 2022, the Sozialgericht (Social Court) annulled the decisions of 18 August 2016 and 18 December 2020 and held that, in accordance with Article 13(1)(b) of Regulation No 883/2004, as amended, which provides that the person concerned is to be subject to the legislation of the Member State in which the registered office of the undertaking employing him or her is situated, the applicant in the main proceedings was covered, during the period at issue, by Swiss social security legislation. That court found that the applicant in the main proceedings had not pursued a substantial part of his activity in his Member State of residence, for the purposes of Article 13(1) of Regulation No 883/2004 and Article 14(8) of Regulation No 987/2009, since only 10.5 working days per quarter, that is to say, 16% of his total working time, had been spent in Germany.
24
On 6 September 2022, GKV-Spitzenverband brought an appeal against that judgment before the Landessozialgericht für das Saarland (Higher Social Court, Saarland, Germany), which is the referring court.
25
The referring court considers that, for the purpose of identifying the social security legislation applicable during the period at issue, the question arises as to whether Article 13(1) of Regulation No 883/2004, as amended, read in conjunction with Article 14(8) of Regulation No 987/2009, must be interpreted as meaning that, for the purpose of determining whether a substantial part of the activity of the person concerned is pursued in a Member State, only activity pursued by that person as an employed person in the Member States and States treated as such must be taken into account or whether activity pursued in third countries must also be taken into account. The referring court states that the existing case-law of the Court of Justice does not provide an answer to that question.
26
The referring court notes that, in the present case, if account were to be taken exclusively of the activities pursued by the applicant in the main proceedings in the Member States during the period at issue, it would have to be considered that 50% of his working time was spent in his Member State of residence, that is to say, a substantial part of his employed activity, for the purposes of Article 13(1) of Regulation No 883/2004, as amended, read in conjunction with Article 14(8) of Regulation No 987/2009. By contrast, if account were to be taken of all the activities pursued by the applicant in the main proceedings, both in the Member States and in third countries, only 16% of his working time would have to be regarded as having been spent in the Member State of residence, which does not amount to a substantial part of his employed activity.
27
In those circumstances, the Landessozialgericht für das Saarland (Higher Social Court, Saarland) decided to stay the proceedings and to refer the following questions to the Court of Justice for a preliminary ruling:
‘(1)
Is Article 13(1) of Regulation No 883/2004[, as amended,] in conjunction with Article 14(8) of Regulation No 987/2009[, to] be interpreted as meaning that, when assessing whether a substantial part of the activity is pursued in a Member State, all of the employee’s activities, including his or her activities in third countries, are to be taken into account?
(2)
Or is Article 13(1) of Regulation No 883/2004[, as amended,] in conjunction with Article 14(8) of Regulation No 987/2009[,] to be interpreted as meaning that, when assessing whether a substantial part of the activity is pursued in a Member State, only those activities of the employee which are pursued in Member States are to be taken into account?’
Consideration of the questions referred
28
It must be noted at the outset that, in accordance with Article 8 of, and Annex II to, the AFMP, the European Union and the Swiss Confederation are to apply among themselves Regulations No 883/2004 and No 987/2009 and that, in that context, the term ‘Member State’ in those regulations is to be understood also to include the Swiss Confederation.
29
Thus, by its two questions referred for a preliminary ruling, which it is appropriate to examine together, the referring court asks, in essence, whether Article 13(1) of Regulation No 883/2004, as amended, read in conjunction with Article 14(8) of Regulation No 987/2009, must be interpreted as meaning that, for the purpose of determining whether a person who pursues an activity as an employed person in several Member States, including his or her Member State of residence, and in several third countries, is pursuing a substantial part of that activity in his or her Member State of residence, within the meaning of Article 13(1) of Regulation No 883/2004, it is necessary to take into consideration only the activity pursued by that person as an employed person in the Member States or also the activity pursued in third countries.
30
As a preliminary point, it should be recalled that, in accordance with settled case-law, the provisions of Title II of Regulation No 883/2004, entitled ‘Determination of the legislation applicable’, which includes Articles 11 to 16 of that regulation, constitute a complete and uniform system of conflict-of-law rules which are intended not only to prevent the simultaneous application of a number of national legislative systems and the complications which might ensue, but also to ensure that the persons covered by that regulation are not left without social security cover because there is no legislation which is applicable to them (see, to that effect, judgment of 16 November 2023, Zakład Ubezpieczeń Społecznych Oddział w Toruniu, C‑422/22, EU:C:2023:869, paragraph 50 and the case-law cited).
31
As is apparent from recitals 1, 3 and 45 of Regulation No 883/2004, that regulation modernises and simplifies the rules laid down in Regulation No 1408/71, while maintaining the same objectives as Regulation No 1408/71, in particular that of coordinating the national social security systems in order to guarantee that the right to the free movement of persons can be exercised effectively and, thereby, to contribute towards improving the standard of living and conditions of employment of persons who move within the European Union (see, to that effect, judgments of 5 June 2014, I, C‑255/13, EU:C:2014:1291, paragraph 41, and of 4 September 2025, Hakamp, C‑203/24, EU:C:2025:662, paragraph 38 and the case-law cited).
32
That purpose is implemented by Article 11 of Regulation No 883/2004, as amended, which provides, in paragraph 1 thereof, that persons to whom that regulation applies are to be subject to the social security legislation of a single Member State only, which is to be determined in accordance with Title II of that regulation.
33
Furthermore, Article 11(3)(a) of that regulation lays down the principle that a person who pursues an activity as an employed person in the territory of a Member State is to be subject to the legislation of that Member State.
34
Nevertheless, that principle is stated to be ‘subject to Articles 12 to 16’ of Regulation No 883/2004, as amended, since, in certain specific situations, the unrestricted application of that principle might in fact create, rather than prevent, administrative complications for workers as well as for employers and social security authorities, which could impede the freedom of movement of the persons covered by that regulation (see, to that effect, judgment of 16 July 2020, AFMB and Others, C‑610/18, EU:C:2020:565, paragraph 43).
35
One of those specific situations is that referred to in paragraph 1 of Article 13 of Regulation No 883/2004, as amended, which concerns the determination of the legislation applicable to the person who normally pursues an activity as an employed person in two or more Member States.
36
According to Article 13(1)(a), the person referred to is to be subject to the legislation of the Member State of residence if he or she pursues ‘a substantial part of his/her activity’ there. By contrast, if the person does not pursue ‘a substantial part of his/her activity’ there, Article 13(1)(b) renders that person, where he or she is employed by a single undertaking or by a single employer, subject to the legislation of the Member State in which the undertaking or the employer has its registered office or place of business (see, to that effect, judgment of 4 September 2025, Hakamp, C‑203/24, EU:C:2025:662, paragraph 43).
37
Thus, the conflict-of-law rules laid down in Article 13(1)(a) and (b) of Regulation No 883/2004, as amended, guarantee a person pursuing an activity as an employed person in two or more Member States social security protection through the application of the legislation of one of the Member States concerned, that is to say, either the legislation of that person’s Member State of residence or the legislation of the Member State in which that person’s employer is established.
38
In so doing, that provision pursues the objective set out in paragraphs 30 and 31 above inasmuch as it lays down, while simplifying the rules introduced by the previous legislation, rules which derogate from the rule laid down in Article 11(3)(a) of that regulation, precisely in order to avoid the complications which, otherwise, might arise if the latter rule were to be applied to situations involving the pursuit of activities in two or more Member States (see, to that effect, judgment of 4 September 2025, Hakamp, C‑203/24, EU:C:2025:662, paragraph 45 and the case-law cited).
39
From that perspective, the aim of the derogating rules laid down in Article 13(1)(a) and (b) of Regulation No 883/2004, as amended, is to ensure that, in accordance with the rule of a single applicable legislation referred to in paragraph 32 above, employed persons working in two or more Member States are subject to the legislation of only one Member State, by establishing for that purpose connecting factors which take into account the objective situation of those workers in order to facilitate their freedom of movement (judgment of 4 September 2025, Hakamp, C‑203/24, EU:C:2025:662, paragraph 46 and the case-law cited).
40
In the present case, the referring court is uncertain as regards the interpretation of Article 13(1) of Regulation No 883/2004, as amended, and of Article 14(8) of Regulation No 987/2009, in particular as to whether the concept of ‘activity’ in the phrase ‘a substantial part of [the person’s] activity in the Member State of residence’ refers only to the activity pursued by that person as an employed person in the Member States or also to that pursued in third countries.
41
In accordance with settled case-law, in interpreting a provision of EU law, it is necessary to consider not only its wording, but also the context in which it occurs and the objectives pursued by the rules of which it is part (judgments of 6 October 1982, Cilfit, 283/81, EU:C:1982:335, paragraph 20, and of 4 September 2025, Kwizda Pharma II, C‑451/24, EU:C:2025:663, paragraph 55).
42
As regards the wording of Article 13(1)(a) of Regulation No 883/2004, as amended, under that provision, a person who normally pursues an activity as an employed person in two or more Member States is to be subject to the legislation of the Member State of residence only if he or she pursues a substantial part of his or her activity there.
43
As regards Article 14(8) of Regulation No 987/2009, it provides, first of all, that, for the purposes of the application of Article 13(1) and (2) of Regulation No 883/2004, as amended, a substantial part of employed or self-employed activity pursued in a Member State means a quantitatively substantial part of all the activities of the employed or self-employed person pursued there, without that necessarily being the major part of those activities. Next, Article 14(8) of Regulation No 987/2009 states that, to determine whether a substantial part of the activities is pursued in a Member State, account is to be taken, in the case of an employed activity, of the working time and/or the remuneration. Lastly, it is clear from Article 14(8) of the regulation that, in the framework of an overall assessment, a share of less than 25% in respect of those criteria is to be an indicator that a substantial part of the activities is not being pursued in the relevant Member State.
44
It must therefore be stated that, on the basis of their wording alone, Article 13(1) of Regulation No 883/2004, as amended, and Article 14(8) of Regulation No 987/2009 do not expressly limit the taking into account of activities pursued by the person concerned as an employed or self-employed person solely to activities pursued in the Member States. That is confirmed, in particular, by the use, in the French-language version of Article 14(8) of Regulation No 987/2009, of the phrases ‘ensemble des activités du travailleur salarié ou non salarié’ and ‘dans le cadre d’une évaluation globale’; those phrases are mirrored, in essence, in many of the other language versions of that provision, in particular the Bulgarian-, Croatian-, Czech-, Danish-, English-, Finnish-, Greek-, Irish-, Italian-, Latvian-, Maltese-, Romanian-, Slovak-, Slovenian-, Spanish-, and Swedish-language versions thereof.
45
Those language versions use, respectively, the words ‘от всички дейности на заето или самостоятелно заето лице’ and ‘В рамките на цялостната оценка’ in the Bulgarian-language version; ‘svih djelatnosti zaposlene osobe ili samozaposlene osobe’ and ‘Ako je u okviru opće ocjene utvrđeno’ in the Croatian-language version; ‘všech činností zaměstnané osoby nebo osoby samostatně výdělečné činné’ and ‘v rámci celkového hodnocení’ in the Czech-language version; ‘af alle arbejdstagerens eller den selvstændige erhvervsdrivendes aktiviteter’ and ‘I forbindelse med en samlet vurdering’ in the Danish-language version; ‘of all the activities of the employed or self-employed person’ and ‘In the framework of an overall assessment’ in the English-language version; ‘palkkatyötä tekevän tai itsenäisen ammatinharjoittajan kaikesta toiminnasta’ and ‘kokonaisarvioinnissa’ in the Finnish-language version; ‘του συνόλου των δραστηριοτήτων του μισθωτού ή μη’ and ‘Στο πλαίσιο συνολικής αξιολόγησης’ in the Greek-language version; ‘de ghníomhaíochtaí uile an duine fhostaithe nó fhéinfhostaithe’ and ‘I réim measúnaithe foriomláin’ in the Irish-language version; ‘dell’insieme delle attività del lavoratore subordinato o autonomo’ and ‘Nel quadro di una valutazione globale’ in the Italian-language version; ‘ka nodarbināta vai pašnodarbināta persona veic kvantitatīvi būtisku visu darbību daļu’ and ‘Saskaņā ar vispārēju novērtējumu’ in the Latvian-language version; ‘tal-attivitajiet kollha tal-persuna impjegata jew li taħdem għal rasha’ and ‘Fil-qafas ta’ evalwazzjoni globali’ in the Maltese-language version; ‘a tuturor activităților persoanei salariate sau persoanei care desfășoară activități independente’ and ‘În cadrul unei evaluări globale’ in the Romanian-language version; ‘všetkých činností zamestnanca alebo samostatne zárobkovo činnej osoby vykonáva v tomto členskom štáte’ and ‘V rámci celkového posúdenia’ in the Slovak-language version; ‘vseh dejavnosti zaposlene ali samozaposlene osebe’ and ‘Če je delež, ugotovljen med splošno presojo’ in the Slovenian-language version; ‘del conjunto de sus actividades por cuenta propia o ajena’ and ‘En el contexto de una evaluación global’ in the Spanish-language version; and ‘allt arbete som anställd eller av all verksamhet som egenföretagare’ and ‘Inom ramen för en samlad bedömning’ in the Swedish-language version.
46
Thus, those various language versions support the conclusion that the wording of Article 14(8) of Regulation No 987/2009 provides that, for the purpose of determining whether an EU citizen who resides in one Member State and who pursues an activity as an employed person in several States, including his or her Member State of residence, another Member State and third countries, is pursuing a substantial part of that activity in the Member State where he or she resides, it is important to take account of all the activities that he or she pursues as an employed person, including activity pursued in third countries.
47
That literal interpretation is borne out by the context in which Article 13(1) of Regulation No 883/2004, as amended, and Article 14(8) of Regulation No 987/2009 occur, and by the objective pursued by those provisions.
48
It must be recalled that the application of the national legislation of the Member State in which the place of activity is located is the general rule governing the system established by Regulation No 883/2004 (see, by analogy, judgment of 27 September 2012, Partena, C‑137/11, EU:C:2012:593, paragraphs 49 and 57) and that the application of the legislation of the Member State in which the person concerned resides appears to be an ancillary rule which comes into play only where that legislation has a link with the employment relationship (see, by analogy, judgment of 19 March 2015, Kik, C‑266/13, EU:C:2015:188, paragraph 58 and the case-law cited). The concept of the ‘location’ of an activity must be understood as referring to the place where, in practical terms, the person concerned carries out the actions connected with that activity (see, by analogy, judgment of 27 September 2012, Partena, C‑137/11, EU:C:2012:593, paragraph 57).
49
In those circumstances, as the Advocate General observed in point 36 of his Opinion, in order to determine the social security legislation to which a worker is subject, it is necessary to examine that worker’s actual situation and to take into account all the activities which he or she pursues, including the activity pursued in third countries, since taking into consideration only the activities pursued in Member States would create a legal fiction far removed from the actual nature of the activity pursued in the Member State of residence.
50
Furthermore, the Court has held that, in order to assess whether an employed person comes within the scope of concept of a ‘person who normally pursues an activity as an employed person in two or more Member States’, within the meaning of Article 13(1) of Regulation No 883/2004, as amended, account must be taken of any possible divergence between, on the one hand, the information provided by the employment contracts at issue and, on the other, the way in which the contractual obligations were performed in practice. If it is apparent from relevant factors other than contractual documents that an employed person’s situation in fact differs from that described in such documents, it is for the institution concerned, for the purposes of the correct application of Regulation No 883/2004, and whatever the wording of those contractual documents, to base its findings on the employed person’s actual situation (see, to that effect, judgment of 16 July 2020, AFMB and Others, C‑610/18, EU:C:2020:565, paragraphs 57 to 59 and the case-law cited).
51
To take into consideration only the activity pursued by the person concerned as an employed person in the Member States, in order to determine whether that person pursues a substantial part of his or her activity in his or her Member State of residence, would amount to disregarding the fact that, as follows from the case-law referred to in paragraphs 41 and 48 above, the determination of the applicable legislation under the conflict-of-law rules laid down, in particular, in Article 13(1) of Regulation No 883/2004, as amended, is not dependent on the free choice of the employed person, undertakings or competent national authorities, but on the objective situation in which that worker finds himself or herself.
52
Consequently, in the framework of the overall assessment required by Article 14(8) of Regulation No 987/2009, the activity pursued by the person concerned as an employed person in third countries must be taken into account in the same way as the activity pursued in the Member States for the purpose of determining that person’s total working time in all the Member States and third countries in which he or she pursued his or her activity as an employed person and, consequently, for the purposes of the subsequent verification as to whether or not 25% of that working time was spent in that person’s Member State of residence.
53
It must be added that the taking into account of all the activity pursued by the person concerned as an employed person in third countries is in no way inconsistent with the rule of a single applicable legislation laid down in Article 11(1) of Regulation No 883/2004, as amended, according to which a worker who resides in one Member State and pursues an activity as an employed person in two or more Member States must be subject to the social security legislation of a single Member State only.
54
Even assuming that that worker pursues a substantial part of his or her activity as an employed person not in his or her Member State of residence but in a third country, that worker will be subject to a single social security legislation, which will be that of the Member State in which his or her employer is established pursuant to Article 13(1) of Regulation No 883/2004, as amended. If it transpires that that employer is established in a third country, that worker will be subject to the legislation of a single Member State only, since Article 14(11) of Regulation No 987/2009 provides that, where a person who resides in a Member State pursues his or her activity as an employed person in two or more Member States on behalf of an employer established outside the territory of the European Union, he or she is to be subject to the legislation of his or her Member State of residence even if that person does not pursue a substantial part of his or her activity as an employed person there.
55
Furthermore, where, as in the case in the main proceedings, the employer’s registered office is in a State to which Regulation No 883/2004 applies, the information relating to the activity pursued in third countries by the employed person, which is necessary in order to assess whether that person pursues a substantial part of his or her activity in the Member State in which he or she resides, can easily be obtained, with the result that the taking into consideration of the activity pursued in the third countries does not entail an ‘increased risk of abuse’, contrary to the submissions of GKV-Spitzenverband and the Belgian and German Governments.
56
As the Advocate General observed in point 45 of his Opinion, it is clear from the case-law of the Court that the proper functioning of the system established by Regulation No 883/2004 requires effective and close cooperation both between the competent institutions of the various Member States and between those institutions and persons falling within the scope of that regulation (judgment of 16 November 2023, Zakład Ubezpieczeń Społecznych Oddział w Toruniu, C‑422/22, EU:C:2023:869, paragraph 53). Therefore, the competent institution of the Member State of residence may, in the framework of the overall assessment that it must carry out pursuant to Article 14(8) of Regulation No 987/2009, ask the institution of the Member State in which the employer’s registered office is situated to verify with that employer whether the services provided by the worker in third countries are actually performed, by requesting, inter alia, that proof such as tickets or invoices be sent.
57
As regards the concerns expressed by GKV-Spitzenverband and by the Belgian and German Governments, claiming that it is not possible to take into account, under Article 13(1) of Regulation No 883/2004, as amended, the activity pursued by the person concerned as an employed person in third countries, since, for self-employed persons, such taking into account is not possible under Article 13(2) of that regulation, it is sufficient to note, as the Advocate General did in point 44 of his Opinion, that the rules applicable to employed and self-employed persons are not in all respects similar, with the result that the solution used for the former is not applicable by analogy to the latter.
58
In the present case, it appears from the order for reference that the share of the activity pursued by the applicant in the main proceedings in his Member State of residence during the period at issue amounts to 16% of all of his activity pursued in both the Member States and third countries. If that were indeed the case, which it is for the referring court to ascertain, the applicant in the main proceedings would have to be regarded as not having pursued a substantial part of his activity as an employed person in his Member State of residence and, consequently, would have to be regarded as being covered, pursuant to Article 13(1)(b) of Regulation No 883/2004, as amended, by the social security legislation of the Member State in which his employer’s registered office is situated, namely the Swiss Confederation.
59
In the light of all the foregoing considerations, the answer to the questions referred is that Article 13(1) of Regulation No 883/2004, as amended, read in conjunction with Article 14(8) of Regulation No 987/2009, must be interpreted as meaning that, for the purpose of determining whether a person who pursues an activity as an employed person in several Member States, including his or her Member State of residence, and in several third countries, is pursuing a substantial part of that activity in his or her Member State of residence, within the meaning of Article 13(1), it is necessary to take into consideration not only the activity pursued by that person as an employed person in the Member States but also the activity pursued in third countries.
Costs
60
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:
Article 13(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, as amended by Regulation (EU) No 465/2012 of the European Parliament and of the Council of 22 May 2012, read in conjunction with Article 14(8) of Regulation (EC) No 987/2009 of the European Parliament and of the Council of 16 September 2009 laying down the procedure for implementing Regulation (EC) No 883/2004 on the coordination of social security systems, as amended by Regulation No 465/2012,
must be interpreted as meaning that, for the purpose of determining whether a person who pursues an activity as an employed person in several Member States, including his or her Member State of residence, and in several third countries, is pursuing a substantial part of that activity in his or her Member State of residence, within the meaning of Article 13(1), it is necessary to take into consideration not only the activity pursued by that person as an employed person in the Member States but also the activity pursued in third countries.
[Signatures]
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)	Language of the case: German.
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)	The names of the parties who have submitted observations and the wording in paragraph 1 have been amended since this document was first put online.