The growing shortage of skilled personnel forces companies to subcontract their work to foreign subcontractors, or make use of foreign employment agencies. These foreign companies have to comply with strict rules regarding the payment of social insurance contributions as well as taxes for their employees. Also, the employees MUST be in the possession of a valid A1 document.
REGULATION (EC) No 883/2004 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 29 April 2004 on the coordination of social security systems (Text with relevance for the EEA and for Switzerland) we quote:
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.
The question that arises is, wether a company, that makes use of the services of a foreign subcontractor or temporary employment agency, can be held responsible, if the A1 document was acquired illegally.
I work in Europe can help you check the A1-documents in cases of doubt.