On 2 April 2020, the European Court of Justice ruled in the joined cases Vueling Airlines (C-370/17 and C-37/18) that the courts and tribunals of the host Member State may not disregard an E101 certificate (the predecessor of the current A1 certificate) when establishing that the certificate has been fraudulently obtained.
A posted worker can continue to be subject to the social security scheme of the sending Member State under certain conditions and need not be affiliated to the social security scheme of the host Member State. The authorities of the sending State can confirm this affiliation in an official document (i.e. the E101 certificate, now replaced by the A1 certificate).
In the past, the European Court of Justice has always ruled that an E101 certificate is binding on the host Member State as long as it has not been withdrawn or declared invalid.
This binding force was restricted for the first time in the Altun case where the Court held that if the authorities of the host Member State have entered into dialogue with the authorities of the sending State through a request for review (based on information indicating fraud) and the authorities of the sending State fail to process this request adequately within a reasonable time, the court or tribunal of the host Member State establishing fraud can disregard the E101 certificate.
Vueling sought to clarify whether the court or tribunal of the host Member State can immediately disregard the certificate in case of fraud (a broad interpretation of Altun) or should it verify first whether the contestation procedure has been initiated? The European Court of Justice ruled that the courts or tribunals of the host Member State can only act against fraudulently obtained E 101 certificates when:
In other words, the Court confirmed the restricted scope of the Altun judgment.
A court or tribunal cannot simply disregard an A1 certificate and unilaterally subject posted workers to the host country social security scheme. Fraudulently obtained A1 certificates can only be disregarded when the conditions set out in the Altun judgment are fulfilled.