🏥 Can I wait 3 days to tell my employer I am sick in Luxembourg?

Quick answer

No — you must tell your employer on the first day; the 3-day deadline concerns only the written medical certificate. Article L.121-6 of the Labour Code imposes two separate duties. First, inform the employer personally on the same day of the impediment (phone, e-mail). Second, get a medical certificate of incapacity to them by the 3rd day of absence at the latest — a deadline counted in calendar days. The certificate must also be sent to the health fund within 3 days. In return, an employee who follows these rules enjoys protection against dismissal for 26 weeks from the day of incapacity. The myth: "I have three days to tell my boss" — false; the notice must be immediate, and only the certificate may arrive by the 3rd day; being slow to notify loses the protection.

📋 The rules

Notify the same day: Article L.121-6 of the Labour Code requires you to inform the employer personally on the first day of incapacity.
Certificate by day 3: the medical certificate must reach the employer by the 3rd day of absence at the latest, in calendar days.
Send it to the fund: the same certificate must be sent to the health fund (CNS) within 3 days to open the sickness benefit.
26 weeks' protection: an employee who has notified and certified properly is protected against dismissal for 26 weeks from the incapacity.
Two separate duties: immediate notice and the certificate are two distinct steps; the 3-day deadline applies only to the second.

🔓 Exceptions

Protection already lost: the protection does not apply if the employee was already summoned to the pre-dismissal meeting or on notice before the incapacity, nor beyond 26 weeks.
No notification: if the employee fails to notify and certify in time, they lose the protection and the employer may, under conditions, terminate the contract.
Special cases: some situations (end of a fixed-term contract, pre-existing gross misconduct) follow their own rules that limit the protection.

⚠️ Penalties & fines

The consequences fall mainly on the careless employee. Failing to notify the same day or to provide the certificate within 3 days brings down the protection against dismissal: the employer regains the ability to end the contract, and the absence can be treated as unjustified, with loss of pay and disciplinary action to follow. Conversely, an employer who dismisses a protected employee — one who notified properly and is within the 26-week window — faces a claim: the dismissal can be declared unfair or void, with reinstatement or damages. The employee must also play by the rules on benefits: without the certificate sent to the health fund in time, payment of the allowance may be delayed or refused. Finally, a false certificate or a feigned illness is gross misconduct that can justify immediate dismissal.

📎 Official sources

Last verified: 2026-07-12

❓ Frequently asked

Do I really have 3 days to tell my employer?

No, you must inform your employer personally on the very first day of your incapacity, by phone or e-mail. The 3-day deadline concerns only the handing in of the written medical certificate, which is a duty separate from immediate notification.

When must I hand in my medical certificate?

The medical certificate of incapacity must reach your employer by the third day of absence at the latest, this deadline being counted in calendar days. The same certificate must also be sent to your health fund within three days to trigger the benefit.

Can I be dismissed during sick leave?

In principle no, because an employee who has met their notification and certificate duties is protected against dismissal for 26 weeks. This protection nonetheless falls away if you did not notify and certify in time, or if you were already summoned to a pre-dismissal meeting before the incapacity.

What happens if I forget to notify my employer?

If you do not notify on the same day and fail to provide the certificate in time, you lose the protection against dismissal. Your absence can then be treated as unjustified, exposing you to a loss of pay and disciplinary action that can go as far as dismissal.

Is the 26-week protection absolute?

No, it assumes you have fulfilled your duties and it does not exceed 26 weeks from the day of incapacity. It also does not apply where the employer had already started the dismissal procedure before you fell ill.

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