Illness during Annual Leave – new obligations for employers and employees as from 1 January 2024

September 15, 2023 | Blog


Earlier this year, Belgian vacation rules were already modified to confirm that employees who fall ill (or whose employment contracts are suspended for certain other reasons) during a period of leave no longer lose these days. These rules apply to leave days taken from 1 January 2024.

In addition, a new Act of 17 July 2023 provides the process which employees should follow in order to notify their employers in case of illness during a period of vacation. Company work rules will also need to be amended.


In February of this year, modifications were made to the Belgian legislation on annual leave to align it with European case law. As of leave year 2024, employees who get ill during their annual leave are entitled to take up these days of annual leave at another moment. In other words, such days of annual leave will no longer be ‘lost’ by the employee but will be converted into days of illness.

The principle applies likewise to other forms of suspension of the employment contract, such as (occupational) accidents, maternity or paternity leave, birth leave, adoption leave or foster parent leave. When those suspensions occur during a period of leave, the lost days will no longer be forfeited. This is the case even if the cause for the suspension occurs only during the annual leave.

Employees whose employment contracts are suspended (because of illness or other forms of suspension) during their leave will be able to take up those days up to 24 months after the end of the relevant year. For example, an employee who falls ill during their 2024 summer holiday will consequently be able to recuperate an equivalent number of days, which need not be taken until 31 December 2026 at the latest.

New notification obligations for employees – amendment of the work rules

To implement these new rules, changes to both the Employment Contracts Act and the Work Rules Act were introduced (Act of 17 July 2023). These changes will also come into force on 1 January 2024.

The new article 31/2 of the Employment Contracts Act provides for additional obligations for employees who become ill during annual leave, if they wish to convert those days into sick leave:

  • Immediate notification: The employees must promptly inform their employer of their location if their place of residence differs from their home address.
  • Mandatory medical certificate: Even when the work rules or a collective bargaining agreement does not require as much, the employee must submit a medical certificate to the employer, confirming the incapacity for work, the anticipated duration of the incapacity for work and whether the employee is permitted to leave their place of residence. This obligation applies even if it concerns the first day of incapacity for work.
  • Request to take ‘lost’ days of leave immediately after incapacity for work: The employees who want to take their ‘lost’ days of leave immediately after a period of incapacity for work must inform their employer thereof at the latest when submitting the medical certificate. The period of leave is thus not automatically extended with the days of sick leave, but this can be requested by the employee. If an employee does not so request, leave days will remain available for a period of 24 months after the relevant year .
  • Guaranteed salary: The employee is entitled to guaranteed pay for days of sick leave coinciding with leave days.

The work rules must include the formalities to be complied with by the employees when they become ill during a period of annual leave. The strict procedure for amending the work rules should, however, not be complied with. The employer can thus easily implement this procedure in the work rules, without agreement with the works council or consultation process with the employees. This can be done with a mere appendix to the work rules, communicated to the employees and the competent Labour law inspectorate.

Action points

Companies should be aware that employees who become ill during periods of annual leave can take up these ‘lost’ days of annual leave at a later stage as of leave year 2024. Additional notification obligations do, however, apply to the employees. Companies should include these additional notification obligations in their work rules by 1 January 2024 so employees are aware of their obligations.

For further information, please contact Julien Hick (+32 2 629 42 53 or, Heleen Franco (+32 2 629 42 73 or or Nour Riyahi (+32 2 629 42 84 or

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