In Belgium, a sick note is only mandatory for the employer if your work rules or a collective agreement require it, or if you ask for one. The employee hands it in within 2 working days. Since 1 January 2026 they may stay off 2 times a year on the first sick day without a certificate. Companies with fewer than 50 employees can exclude this.
The 2026 sick note rules for employers
Since 1 January 2026, the sickness rules have changed on several points. Much of what you find online still mentions three days without a certificate or a two-week relapse period. This is what applies now:
| Question | Rule in 2026 |
|---|---|
| Who decides whether a certificate is needed? | A collective agreement or the work rules, or you case by case on request |
| Deadline | 2 working days, unless a collective agreement or the work rules say otherwise |
| Days without a certificate | 2 times per calendar year, first sick day only (until end 2025: 3) |
| Small company | Fewer than 50 employees on 1 January: you may exclude certificate-free days with an explicit clause |
| Sick during holiday | Always a certificate, including the first day |
| Relapse | 8 weeks (until end 2025: 14 days) |
| Medical force majeure | Procedure possible after 6 months of uninterrupted sickness (until end 2025: 9) |
Is a sick note for the employer mandatory?
The employee must always tell you straight away that they are ill. That is separate from the certificate. The certificate itself is only required in two cases:
- Your work rules (arbeidsreglement) or a collective agreement require it. The employee then sends it without being asked.
- You ask for it. Without a rule in the work rules, you have to ask every time, and the deadline only runs from your request.
The certificate states the incapacity for work, its likely duration and whether the employee may leave home for a check. A certificate without these is incomplete.
When must the employee hand in the sick note?
Without another rule, the employee hands in the certificate within 2 working days. The deadline starts on the first day of incapacity, or on the day they received your request. They may post it, email it if your work rules allow, or drop it off at work.
A collective agreement or your work rules may set a different deadline. In case of force majeure, such as admission to intensive care, the certificate may arrive later.
Separately, the employee must report the incapacity to their health insurance fund: a blue-collar worker within 14 calendar days, a white-collar employee within 28 calendar days. That is their responsibility, but an employee who forgets loses part of their benefit and often calls you about it.
Absent without a sick note: certificate-free days
An employee may, 2 times per calendar year, stay off on the first day of a sickness without a certificate, even if your work rules require one. This applies to a one-day sickness and to the first day of a longer one. From the second day, the certificate is required.
Three things still apply on such a day:
- the employee informs you straight away;
- if they are not staying at their usual address, they give you the address;
- you may send a control doctor. See how in our blog on sending a control doctor as employer.
Small companies with fewer than 50 employees on 1 January of the year may opt out. Only with an explicit clause in a collective agreement or the work rules. An existing general certificate requirement is not enough. Without a new clause, the certificate-free days apply in your company too.
What if the sick note comes late or not at all?
If the certificate arrives late without force majeure, the employee can lose their right to guaranteed salary for the sick days before the day they hand it in or send it. From then on, you pay as normal. If no certificate arrives at all, you can treat the absence as unjustified and refuse pay for those days.
An example. A white-collar employee reports sick on Monday, and your work rules require a certificate within 2 working days. They only hand in the certificate on Friday. You can refuse pay for Monday to Thursday and pay guaranteed salary from Friday, within the 30-day period. Record the decision in writing and refer to the article in your work rules.
What you pay per day is set out in our guide on guaranteed salary in Belgium.
Can an employer refuse a sick note?
You cannot simply set aside a complete certificate handed in on time. You can:
- ask for a correct certificate if the incapacity or likely duration is missing;
- withhold pay for the days before a late certificate;
- send a control doctor if you doubt the sickness itself.
What you may not do: ask for the diagnosis. It does not belong on the certificate for the employer and is covered by medical confidentiality.
A clause for your work rules
An example to adapt. Use the last sentence only if you have fewer than 50 employees and want to exclude certificate-free days.
Incapacity for work. The employee informs their manager immediately at the start of the incapacity for work, by phone and before the start of their working day, and gives their address of stay if it is not their usual address. Within 2 working days they provide a medical certificate stating the incapacity, its likely duration and whether they may travel. By way of derogation from Article 31, §2/1, first paragraph, of the Act of 3 July 1978, the employee also provides a medical certificate for the first day of every incapacity for work.
Download the work rules template with this clause in Word and PDF, in Dutch and French.
Amending the work rules follows the normal procedure. An annex is not enough. See our guide on drawing up work rules.
Checklist for the first sick day
- Record the time of the sick report and the address of stay.
- Check whether the employee has already used a certificate-free day this year. They have 2 per calendar year.
- Ask for the certificate if your work rules do not require it. The deadline runs from your request.
- Check whether it is a relapse: did a sickness end in the past 8 weeks?
- Decide whether a control doctor makes sense.
- Pass the sickness period and the certificate to your payroll.
All of this year's changes, including for long-term sickness, are in our news item on return-to-work rules in 2026.
What Business Centrum does for you
Business Centrum tracks how many certificate-free days each employee has used, processes sickness periods in your payroll together with Acerta and checks whether your work rules follow the 2026 rules. Sickness and leave run through our leave and absence service.