From 1 April 2007, foreign companies who wish to second an employee to Belgium will be under an obligation to file an electronic declaration at the social security administration prior to the commencement of the secondment. This obligation to file rests with the employer of the secondee or with the self-employed worker himself. The legislation provides that a Royal Decree may exclude specific categories of workers from the scope of application. Whenever an employer (or a self-employed worker) has made a declaration, he will receive an acknowledgement of receipt from the social security administration. The end user of the services provided by the secondee or self-employed worker will have an obligation to verify that the worker is in possession of the receipt, after filing their declaration. If this is not the case, the end user must communicate the identification data of the concerned worker to the social security administration.

The non observation of these rules can give rise to administrative or criminal sanctions.