Working time reduction


Principle of working time

Working time is the time during which the employee is at the disposal of the employer. Working time is not equal to actual work, and may include periods that are significantly longer than actual performance.

Limits of working time

  • Minimum limit: 3 hours per day
  • Maximum limit: 8 hours per day or 38 hours per week (may be increased to 9 hours per day)
  • General rule:
    • 38 hours actual per week
    • 38 hours per week on average within a specified reference period
  • Note: in principle, the normal weekly working time may not exceed 40 hours.

In order to know the number of weekly working hours that apply in the company, one must always check which joint committee the company belongs to and which collective labour agreements have been concluded within this joint committee.

In the meantime, several sectors have limited the number of weekly working hours to less than 38 hours.

Principle Reduction of working hours (ADV)

In most cases where the normal working time limits are exceeded, catch-up rest must be granted. In this way, the normal weekly working time is respected within a certain reference period. This reference period is normally one trimester, but can also be extended to a maximum of one year.

Since 1 January 2003, the legal maximum limit has been raised to 38 hours per week. A distinction was made between:

Employers who switched before 1 January 2003

Free choice of working time reduction

  • effective reduction to 38 hours per working week by reducing the hours worked
  • granting of a number of days of catch-up rest while retaining the same working hours.

Employers who did not change before 1 January 2003

  • automatic reduction to 38 actual hours per working week

Note: in certain companies, working hours can be both reduced (recovery of working hours) and increased (shift work).

Deviations from the maximum limits on working hours are therefore always possible. For example: Saturday work, exceptional increase in workload, unforeseen necessity, etc.

Different forms of reduced working hours

Effective reduction of daily working hours

Working time can be reduced by cutting the workers' daily hours. Example: 7h36 becomes 7h24 -> 38 hours becomes 37 hours

Effective reduction of weekly working time

Working time can be reduced by reducing the weekly limit of working time. Example: reduction of working hours by 1 hour on the last working day -> 38 hours becomes 37 hours

Reduction of working time by granting additional rest days

Working time can be reduced by granting additional rest days without reducing the daily and weekly working time.

Example a: 12 supplementary rest days are granted. The weekly working time is reduced to an average of 38 hours on an annual basis. The daily and weekly working hours remain 8 hours and 40 hours respectively.

Example b: Grant of 6 days of catch-up rest. The weekly working time is reduced from 38 to 37 hours (derogation from the sectoral working time).

Temporary agency workers employed by a client-user

The temporary agency worker follows the working hours and timetable applicable at the client-user

The employment contract of the temporary worker must stipulate the average weekly working hours and the actual working hours.

The temporary worker follows the system of reduced working hours that applies to the client-user.

Since 1 January 2000, temporary workers have followed the same rules as those that apply to the client-user's permanent staff regarding the granting of reduced working hours. This applies both to the payment of catch-up leave (paid or unpaid) and to the actual use of catch-up leave.

Practical consequences for temporary agency worker

In practice, the absorption of catch-up rest days by the client-user is often a problem for the temporary agency worker. The following principles are therefore applied:

Catch-up rest days are always declared to the NSSO.

It is not important whether they are taken during the employment contract or are mentioned on the C4.

Payment and recording of catch-up rest days is settled per client-user.

The temporary worker must be given the opportunity to take the remaining catch-up rest days before starting a new assignment.

An extension contract can be drawn up for the taking of catch-up rest days. If this is not the case, the remaining days must be mentioned on the C4. Naturally, the corresponding salary for the remaining catch-up rest days must then also be paid.

Short-term assignments

It is possible for a temporary worker to have catch-up rest for a period of less than one working day. In that case too, the catch-up rest will be paid out in the form of a bonus.


In order to know which rules apply, it is important to check which sector the company belongs to and whether there are any deviating provisions within this sector.


Heidi Vergauwe

Dedicated and meticulous Payroll & HR Advisor, always willing to go for the extra (s)mile!