Whereas clause 4.2 of the Framework Agreement on part-time work and Article 7 of Directive 2003/88 do not require Member States to make a new calculation of entitlement to annual leave already accumulated where a worker increases the number of hours worked, neither do they preclude the Member States from adopting provisions more favourable to workers and making such a new calculation.

While it is the case that the application of that principle is appropriate for the grant of annual leave for a period of part-time employment, since for such a period the reduction of the right to annual leave, in comparison to that granted for a period of full-time employment, is justified on objective grounds, the fact remains that that principle cannot be applied ex post to a right to annual leave accumulated during a period of full-time work.

That conclusion is not affected by the application of the pro rata temporis principle laid down in clause 4.2 of the Framework Agreement on part-time work.

As regards the accrual of entitlement to paid annual leave, it is necessary to distinguish periods during which the worker worked according to different work patterns and the number of units of annual leave accumulated in relation to the number of units worked must be calculated for each period separately.

Clause 4.2 of the Framework Agreement on part-time work, annexed to Directive 97/81 concerning the Framework Agreement on part-time work concluded by UNICE, CEEP and the ETUC, as amended by Directive 98/23, and Article 7 of Directive 2003/88 concerning certain aspects of the organisation of working time must be interpreted as meaning that, in the event of an increase in the number of hours of work performed by a worker, the Member States are not obliged to provide that the entitlement to paid annual leave already accrued, and possibly taken, must be recalculated retroactively according to that worker’s new work pattern. A new calculation must, however, be performed for the period during which working time increased.

Clause 4.2 of the Framework Agreement, annexed to Directive 97/81 on part-time work concerning the Framework Agreement on part-time work concluded by UNICE, CEEP and the ETUC, as amended by Directive 98/23, and Article 7 of Directive 2003/88 concerning certain aspects of the organization of working time must be interpreted as meaning that the calculation of the entitlement to paid annual leave is to be performed according to the same principles, whether what is being determined is the allowance in lieu of paid annual leave not taken where the employment relationship is terminated, or the outstanding annual leave entitlement where the employment relationship continues.

The expression ‘paid annual leave’ in Article 7(1) of Directive 2003/88 means that, for the duration of annual leave within the meaning of that directive, remuneration must be maintained and that, in other words, workers must receive their normal remuneration for that period of rest.

In addition, with regard to a worker who has not been able, for reasons beyond his control, to exercise his right to paid annual leave before termination of the employment relationship, the allowance in lieu to which he is entitled must be calculated so that the worker is put in a position comparable to that he would have been in had he exercised that right during his employment relationship. It follows that the worker’s normal remuneration, which is that which must be maintained during the rest period corresponding to the paid annual leave, is also decisive as regards the calculation of the allowance in lieu of annual leave not taken by the end of the employment relationship.

Therefore, the calculation of the allowance in lieu of annual leave not taken must be carried out according to the same method as that used for the calculation of normal remuneration, the time when that calculation takes place being, in principle, irrelevant.

However, it is not impossible that the time when that calculation is to be performed may have an effect on the manner in which it is carried out.

Where remuneration is made up of several elements, the determination of normal remuneration requires a specific analysis. In such a situation it is for the national court or tribunal to assess, in the light of the principles identified in the case-law, whether, on the basis of an average over a reference period which is considered to be representative, the methods of calculating normal remuneration and the allowance in lieu of paid annual leave not taken achieve the objective pursued by Article 7 of Directive 2003/88.

(see paras 50-54, 57, operative part 2)