Regulated at European level, the posting of workers is a practice used between companies located in different countries A worker is posted when their original employer sends them to work, for a temporary period, in another company. Posting has been defined as a specific form of labour mobility within the EU. Although posting only affects around 1% of the workforce in the EU, it has generated extensive debate due to fraudulent practices hampering the enforcement of, and compliance with, existing regulations. Changes in the location of work, raise various questions – namely, who is the employer and which national regulations apply. The use of temporary agencies, subcontracting and posting of self-employed workers gives rise to additional problems.