1) This request for a preliminary ruling concerns the interpretation of Article 7(1) 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) and of Article 31 of the Charter of Fundamental Rights of the European Union (‘the Charter’).

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3) Article 31 of the Charter, entitled ‘Fair and just working conditions’, provides:

‘1. Every worker has the right to working conditions which respect his or her health, safety and dignity.

2. Every worker has the right to limitation of maximum working hours, to daily and weekly rest periods and to an annual period of paid leave.’

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20) In those circumstances, the Arbeitsgericht Verden (Labour Court, Verden, Germany) decided to stay the proceedings and refer the following questions to the Court for a preliminary ruling:

‘(1) Are Article 31 of the [Charter] and Article 7(1) of [Directive 2003/88] to be interpreted as precluding national legislation under which it may be provided in collective agreements that reductions in earnings occurring in the period of calculation as a result of short-time work affect the calculation of the payment for annual leave with the result that the worker receives a lower remuneration for annual leave for the duration of the period of annual leave of at least four weeks, or receives a lower allowance in lieu of leave after the employment relationship has ended, than he would receive if the calculation of the remuneration for annual leave were based on the average earnings which the worker would have received in the period of calculation without such reductions in earnings? If so, what is the maximum percentage, with reference to the worker’s full average earnings, that a collectively agreed reduction, permitted by national legislation, of the remuneration for annual leave may have as a result of short-time work in the period of calculation in order for the interpretation of that national legislation to be regarded as in conformity with EU law?

(2) If Question 1 is answered in the affirmative: Do the general principle of legal certainty laid down by EU law and the principle of non-retroactivity require that the possibility of relying on the interpretation which the Court places, in the preliminary ruling to be given in the present case, on Article 31 of the [Charter] and on Article 7(1) of [Directive 2003/88] be limited in time, with effect for all parties, because the highest national courts have previously ruled that the relevant national legislation and collectively agreed rules are not amenable to an interpretation in conformity with EU law? If the Court answers this question in the negative: Is it compatible with EU law if, on the basis of national law, the national courts grant protection of legitimate expectations to employers who have relied on the continued application of the case-law developed by the highest national courts, or is the grant of protection of legitimate expectations reserved for the Court of Justice of the European Union?’

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21) By its first question the referring court asks, in essence, whether Article 7(1) of Directive 2003/88 and Article 31(2) of the Charter must be interpreted as precluding national legislation, such as that at issue in the main proceedings, which, for the purpose of calculating remuneration for annual leave, allows collective agreements to provide for account to be taken of reductions in earnings resulting from the fact that during the reference period there were days when no work was actually performed owing to short-time working, with the consequence that the worker receives, for the duration of the minimum period of annual leave to which he is entitled under Article 7(1) of the directive, remuneration for annual leave that is lower than the remuneration which he would have received had it been calculated on the basis of his average pay during the reference period without taking into account those reductions in earnings. If the answer to that question is in the affirmative, that court is uncertain, in the context of the interpretation of the national legislation in accordance with EU law which it could have to carry out, as to the level to which remuneration for annual leave may be reduced without infringing EU law.

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23) That right, which is enjoyed by all workers, is expressly set out in Article 31(2) of the Charter, which Article 6(1) TEU recognises as having the same legal value as the Treaties (judgments of 8 November 2012, Heimann and Toltschin, C‑229/11 and C‑230/11, EU:C:2012:693, paragraph 22; of 29 November 2017, King, C‑214/16, EU:C:2017:914, paragraph 33; and of 4 October 2018, Dicu, C‑12/17, EU:C:2018:799, paragraph 25).

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53) In the light of the foregoing, the answer to the first part of the first question is that Article 7(1) of Directive 2003/88 and Article 31(2) of the Charter must be interpreted as precluding national legislation, such as that at issue in the main proceedings, which, for the purpose of calculating remuneration for annual leave, allows collective agreements to provide for account to be taken of reductions in earnings resulting from the fact that during the reference period there were days when no work was actually performed owing to short-time working, with the consequence that the worker receives, for the duration of the minimum period of annual leave to which he is entitled under Article 7(1) of the directive, remuneration for annual leave that is lower than the normal remuneration which he receives during periods of work. It is for the referring court to interpret the national legislation, so far as possible, in the light of the wording and the purpose of Directive 2003/88, in such a way that the remuneration for annual leave paid to workers in respect of the minimum annual leave provided for in Article 7(1) is not less than the average of the normal remuneration received by those workers during periods of actual work.

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55) By its second question, the referring court asks, in essence, whether it is possible to limit the temporal effects of the present judgment in the event that the Court rules that Article 7(1) of Directive 2003/88 and Article 31 of the Charter must be interpreted as precluding national legislation such as that at issue in the main proceedings. In the event that such a limitation is refused, the referring court asks the Court, in essence, whether EU law must be interpreted as precluding national courts from protecting, on the basis of national law, the legitimate expectation of employers that the case-law of the highest national courts, which confirmed the lawfulness of the provisions concerning paid annual leave in the BRTV-Bau, will continue to apply.

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64) Since these proceedings are, for the parties to the main proceedings, a step in the action pending before the national court, the decision on costs is a matter for that court. Costs incurred in submitting observations to the Court, other than the costs of those parties, are not recoverable.

On those grounds, the Court (Fourth Chamber) hereby rules:

1. Article 7(1) 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 and Article 31(2) of the Charter of Fundamental Rights of the European Union must be interpreted as precluding national legislation, such as that at issue in the main proceedings, which, for the purpose of calculating remuneration for annual leave, allows collective agreements to provide for account to be taken of reductions in earnings resulting from the fact that during the reference period there were days when no work was actually performed owing to short-time working, with the consequence that the worker receives, for the duration of the minimum period of annual leave to which he is entitled under Article 7(1) of the directive, remuneration for annual leave that is lower than the normal remuneration which he receives during periods of work. It is for the referring court to interpret the national legislation, so far as possible, in the light of the wording and the purpose of Directive 2003/88, in such a way that the remuneration for annual leave paid to workers in respect of the minimum annual leave provided for in Article 7(1) is not less than the average of the normal remuneration received by those workers during periods of actual work.

2. It is not appropriate to limit the temporal effects of the present judgment and EU law must be interpreted as precluding national courts from protecting, on the basis of national law, the legitimate expectation of employers that the case-law of the highest national courts, which confirmed the lawfulness of the provisions concerning paid annual leave in the Bundesrahmentarifvertrag für das Baugewerbe (Federal collective framework agreement for the construction industry), will continue to apply.