Judgment_paragraph 42 · Criminal proceedings against FU and Others (C-410/21)

42As a preliminary point, it should be recalled that the A1 certificate, which replaced the E 101 certificate provided for by Regulation No 574/72, corresponds to a standard form issued, in accordance with Title II of Regulation No 987/2009, by the institution designated by the competent authority of the Member State whose social security legislation is applicable, in order to certify, in accordance with, inter alia, Article 19(2) of that regulation, that workers who are in one of the situations referred to in Title II of Regulation No 883/2004 are subject to the legislation of that Member State. In so doing, by virtue of the principle that workers must be covered by only one social security system, that certificate thus necessarily means that the other Member States’ social security systems cannot apply (judgment of 14 May 2020, Bouygues travaux publics and Others, C‑17/19, EU:C:2020:379, paragraphs 38 and 39 and the case-law cited).