The Court of Justice delivered last week (14 May 2020) its judgment in case C-17/19 (Bouygues travaux publics, Elco construct Bucarest, Welbond armatures), which is about the A 1 certificate (Article 19(2) of Regulation No 987/2009 – see below):

Question: “‘Must [Article] 11 of Regulation [No 574/72] and [Article] 19 of Regulation [No 987/2009] be interpreted as meaning that an E 101 Certificate issued by the institution designated by the competent authority of a Member State, under […] Regulation No 1408/71 … or an A 1 Certificate issued under Article 13(1) of Regulation No 883/2004 … is binding on the courts of the Member State in which the work is carried out when it comes to determining the legislation applicable, not only as regards the social security system but also as regards employment law, where such legislation defines the obligations of employers and the rights of employees, so that, having heard the arguments of the parties, those courts can disregard the abovementioned certificates only if, on the basis of an assessment of specific evidence, collected in the course of the judicial investigation, which supports the conclusion that the certificates were fraudulently obtained or relied on and which the issuing institution failed to take into account within a reasonable time, the said courts make a finding of fraud, comprised, as regards its objective element, by the failure to meet the conditions laid down in either of the aforementioned provisions of Regulations [No 574/72] and [No 987/2009] and, as regards its subjective element, by the intention of the accused person to evade or circumvent the conditions for the issue of that certificate, in order to obtain the advantages attaching thereto?’”

Reminder of some key provisions:

“Regulation No 883/2004
8 Regulation No 1408/71 was repealed and replaced with effect from 1 May 2010 by Regulation (EC) No 883/2004 of the European Parliament and of the Council of 29 April 2004 on the coordination of social security systems
[…]
10 Article 13(2)(a) of Regulation No 1408/71 was replaced, in essence, by Article 11(3)(a) of Regulation No 883/2004, which provides that ‘subject to Articles 12 to 16 … 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’.
11 Article 14(1)(a) of Regulation No 1408/71 was replaced, in essence, by Article 12(1) of Regulation No 883/2004, which provides that ‘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 that person is not sent to replace another posted person’.
12 Article 14(2)(b) of Regulation No 1408/71 was replaced, in essence, by Article 13(1) of Regulation No 883/2004, which provides:
‘A person who normally pursues an activity as an 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 the Member State of residence; or
(b) if he/she does not pursue a substantial part of his/her activity in the Member State of residence…’
[…]

Regulation No 987/2009

15 Regulation No 574/72 was repealed and replaced, with effect from 1 May 2010, by Regulation No 987/2009.
16 Article 5(1) of Regulation No 987/2009 provides:
‘Documents issued by the institution of a Member State and showing the position of a person for the purposes of the application of the basic Regulation and of the implementing Regulation, and supporting evidence on the basis of which the documents have been issued, shall be accepted by the institutions of the other Member States for as long as they have not been withdrawn or declared to be invalid by the Member State in which they were issued.’
17 Article 19(2) of Regulation No 987/2009, which partly replaced Article 11(1)(a) and Article 12a(2)(a) and (4)(a) of Regulation No 574/72, provides that ‘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 indicate, where appropriate, until what date and under what conditions’. That attestation is issued by means of a certificate (‘the A 1 Certificate’)”.

Response from the Court of Justice: “Article 11(1)(a), Article 12a(2)(a) and (4)(a) of Council Regulation (EEC) No 574/72 of 21 March 1972 laying down the procedure for implementing Regulation (EEC) No 1408/71 on the application of social security schemes to employed persons, to self-employed persons and to their families moving within the Community […] and Article 19(2) 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, must be interpreted as meaning that an E 101 Certificate, issued by the competent institution of a Member State, under [Regulation (EEC) No 1408/71] to workers employed in the territory of another Member State, and an A 1 Certificate, issued by that institution, under Article 12(1) or 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 […] to such workers, are binding on the courts or tribunals of the latter Member State solely in the area of social security”.

Source: here