The purpose of this article was not only to determine the subjective scope of the new directive on transparent and predictable working conditions in the European Union, but primarily to reflect on the concept of worker functioning in the EU legislation. For this purpose, the authors reviewed the occurrence of this notion in the acts of the EU legislation significant in this matter, as well as selected judgments of the Court of Justice of the European Union. On this basis, the authors pointed out a number of worker's features established in the EU law, and then compared them with the premises expressed in the Polish national legislation. Moreover, the authors indicated the threat associated with different understanding of similar premises of the EU and national law.