The statute "Workable and Flexible Work" has fixed the internal limit at 143 hours and the reference period at one year.
The Labour Act of 16 March 1971 determines the circumstances justifying performance of overtime. In addition, alternative work time schedules may be installed as a result of which the number of hours of work performed may exceed during a certain period of time the normal number of hours of work in accordance with the normal work time schedule (the "limited flexibility": see on this subject part 1).
The total number of hours of work performed during a period as determined (in principle a quarter) could not exceed the normal number of hours of work in accordance with the normal work time schedule with more than 78. Once that limit reached, compensation rest must be taken.
If a reference period of one year (as opposed to the standard reference period of a quarter) applies, that maximum was fixed at 91 hours.
This limit could be increased to 130 hours and 143 hours subject to compliance with special procedures, as laid down in the Royal Decree of 11 September 2013 (collective labour agreement at sector level; collective labour agreement at company level signed by all trade unions represented in the union delegation; amendment of the work regulations approved by the competent joint labour-management committee).
The statute "Workable and Flexible Work" has now fixed this maximum number of hours generally at 143 hours and the reference period is generally determined at one year.
The limit may be increased by collective labour agreement, rendered compulsory by royal decree.
The first 25 hours performed within the system of "voluntary overtime" (see on that subject part 2) are not included for the calculation of the internal limit of 143 hours. The other hours of voluntary overtime are.
The number of hours of voluntary overtime, which is not included for the calculation of the internal limit, can be increased up to a maximum of 60 hours by collective labour agreement rendered compulsory by royal decree. It seems rather unlikely that such collective labour agreements will effectively be entered into considering the reluctance of the trade unions.