Where a system for organising working time is implemented over a reference period longer than a week, overtime is deducted at the end of this reference period.
This reference period may not exceed three years in the case of a collective agreement and nine weeks in the case of a unilateral decision by the employer.
If the reference period is annual, hours worked in excess of 1,607 hours constitute overtime.
If the reference period is less than or greater than one year, hours worked in excess of an average weekly working time of thirty-five hours calculated over the reference period constitute overtime.