Charter article 31 

64. As regards payment in respect of holidays, it must be recalled at the outset that, under Article 31(2) of the Charter, every worker has the right to an annual period of paid leave.

65. That right, which is set out in Article 7 of Directive 2003/88/EC of the European Parliament and of the Council of 4 November 2003 concerning certain aspects of the organisation of working time (OJ 2003 L 299, p. 9) from which that directive permits no derogation, provides that every worker is entitled to a period of paid annual leave of at least four weeks. The right to paid annual leave which, according to settled case-law, must be regarded as a particularly important principle of EU social law, is thus granted to every worker, whatever his place of employment (see, to that effect, judgments in Schultz-Hoff and Others, C‑350/06 and C‑520/06, EU:C:2009:18, paragraph 54, and Lock, C‑539/12, EU:C:2014:351, paragraph 14).

66. The Court’s case-law also makes clear that the term ‘paid annual leave’ in Article 31 of the Charter and Article 7(1) of Directive 2003/88 means that, for the duration of annual leave within the meaning of those provisions, remuneration must be maintained and that, in other words, workers must receive their normal remuneration for that period of rest (see judgments in Robinson-Steele and Others, C‑131/04 and C‑257/04, EU:C:2006:177, paragraph 50, and Lock, EU:C:2014:351, paragraph 16).

67. According to that case-law, Directive 2003/88 treats entitlement to annual leave and to a payment on that account as being two aspects of a single right. The purpose of requiring payment to be made in respect of that leave is to put the worker, during such leave, in a position which is, as regards his salary, comparable to periods of work (see Lock, EU:C:2014:351, paragraph 17 and the case-law cited).

68. Thus, as the Advocate General has observed in point 89 of his Opinion, the pay which the worker receives during the holidays is intrinsically linked to that which he receives in return for his services.

69. Accordingly, Article 3 of Directive 96/71, read in the light of Articles 56 TFEU and 57 TFEU, must be interpreted as meaning that the minimum pay which the worker must receive, in accordance with point (b) of the second indent of Article 3(1) of the directive, for the minimum paid annual holidays corresponds to the minimum wage to which that worker is entitled during the reference period.

Charter article 47 

19. By questions 1 to 5, which it is appropriate to consider together, the referring court is, in essence, uncertain about whether, in circumstances such as those of the case before it, Directive 96/71, read in the light of Article 47 of the Charter, prevents a rule of the Member State of the seat of the undertaking that has posted workers to the territory of another Member State — under which the assignment of claims arising from employment relationships is prohibited — from barring a trade union, such as the Sähköalojen ammattiliitto, from bringing an action before a court of the second Member State, in which the work is performed, to recover pay claims which have been assigned to it by those posted workers.

20. In that regard, it is apparent not only from the information provided to the Court by the referring court, but also from the answers to the questions raised at the hearing before the Court, that the standing of the Sähköalojen ammattiliitto to bring proceedings before the referring court is governed by Finnish procedural law, which is applicable according to the principle of lex fori. Nor is it disputed that, under Finnish law, the applicant has standing to bring proceedings on behalf of the posted workers.

21. Thus, the rules set out in the Polish Labour Code, to which ESA refers, are irrelevant with regard to the locus standi of the Sähköalojen ammattiliitto before the referring court and do not prevent that trade union from bringing an action before the Satakunnan käräjäoikeus.

22. Moreover, the subject-matter of the main proceedings relates to the determination of the scope of the concept of ‘minimum rates of pay’, within the meaning of Directive 96/71, to which the Polish workers posted to Finland are entitled.

23. The second subparagraph of Article 3(1) of Directive 96/71 makes absolutely clear that questions concerning ‘minimum rates of pay’ within the meaning of the directive are governed, whatever the law applicable to the employment relationship, by the law of the Member State to whose territory the workers are posted in order to carry out their work: in this case, Finland.

24. Furthermore, it is apparent in particular from the wording of the second question raised by the referring court that the assignment of pay claims to the Sähköalojen ammattiliitto with a view to their recovery for the posted workers is in conformity with Finnish law and that, moreover, the Polish undertaking which engaged those workers has a branch in Finland to which they were posted.

25. That being so, there is nothing in the present case, contrary to what was argued by ESA before the referring court, which gives any ground for calling in question the action which the Sähköalojen ammattiliitto has brought before the Satakunnan käräjäoikeus.

26. The answer to questions 1 to 5 is therefore that, in circumstances such as those of the case before the referring court, Directive 96/71, read in the light of Article 47 of the Charter, prevents a rule of the Member State of the seat of the undertaking that has posted workers to the territory of another Member State — under which the assignment of claims arising from employment relationships is prohibited — from barring a trade union, such as the Sähköalojen ammattiliitto, from bringing an action before a court of the second Member State, in which the work is performed, in order to recover for the posted workers, pay claims which relate to the minimum wage, within the meaning of Directive 96/71, and which have been assigned to it, that assignment being in conformity with the law in force in the second Member State.