Drawing on research conducted by the authors in the frame of the POSTING.STAT research project, this article explores the legal fiction that posted workers do not, at any time, ‘gain access’ to the labour market of a host State where they are in fact (temporarily) working. Hence, it analyses following question: at what point and under which circumstances are posted workers considered as working in a given Member State? To do so, it considers the use of the concept of ‘labour market’ across the case law of the Court of Justice concerning posting workers, to identify the constitutive elements of the implicit definition adopted by the Court. This analysis is compared with economic/statistical assumptions applied when measuring employment in a country. From a statistical point of view, the labour market appears to be demarcated by the place of establishment of the employer, thus excluding work (i.e., services) carried out through non-established employers. Consequently, cross-border labour mobility through the freedom to provide services does not fall within these boundaries and means that posted workers are counted in the employment statistics of their Member State of origin. The approach to posted workers in the labour market of the host State is therefore not only a legal, but also a statistical/economic, fiction. Based on an empirical reality that shows a strong concentration of posted workers in certain sectors, Member States or regions, we argue that courts and legislators, and also national statistical offices, should reconsider this approach.