A1 certification – limited binding effect

The ECJ has confirmed that the binding effect of A1 posting certificates does not apply without restrictions.


If the social authority of one Member State issues an A1 posting certificate for an employee, the social authorities of the other Member States are bound by the content of this certificate. If they have doubts about the accuracy of the certificate, they must contact the authorities that issued it. Only if the issuing authority cancels the certificate this also affects the authorities of the other states.

Up to now, this principle has applied almost without exception. However, the ECJ has now confirmed that the member states may come to their own different assessment if it can be proven from their point of view that the certificate was obtained fraudulently – i.e. through false information – and the issuing authority does not respond to such information.

In the specific case, a Bulgarian construction company had received A1 certificates for its employees by providing false information. The Belgian social authority pointed this out to the Bulgarian social authority and asked them to withdraw the posting certificate. However, the Bulgarian authority simply confirmed the original view and did not even consider the arguments put forward by the Belgian authority.

A Belgian criminal court subsequently convicted the workers for social security fraud. The ECJ confirmed this approach. In the ECJ’s view, the binding effect of A1 certificates is limited if they have been obtained in a fraudulent or abusive way. In such cases, the courts of the Member States are entitled to make divergent findings if (i) the issuing authority does not re-examine the matter within a reasonable time and (ii) the accused are guaranteed the right to a fair trial.

It is to be expected that courts will make more frequent use of this possibility in the future, especially as the social authorities of some member states seem to issue A1 certificates too lightly and are not willing to question such decisions critically even in the case of indications of fraud.

Source: ECJ, decision of 06.02.2018, ref: C-359-16

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