Sick Leave in Luxembourg: Certificate, Pay and Deadline Rules

Calling in sick in Luxembourg involves two separate duties: tell the employer immediately and, when the absence reaches three days, deliver the medical certificate on time. Completing only one of those steps can weaken statutory dismissal protection. The safest practice is to notify in writing, keep evidence of delivery and never wait for the deadline if a certificate is already available.

The rules apply to residents and cross-border employees. A doctor in the employee's country of residence can issue the certificate, although French, German and Belgian forms have different numbers of sheets. The official Guichet.lu incapacity guide sets out the current procedure.

What to do on day one and by day three

On the first day missed because of illness or accident, inform the employer or its representative as soon as possible. Notice may be oral or written and can be given through another person, but telling only a colleague is not enough. Email or a message to the designated manager gives the employee useful proof of timing.

If the incapacity lasts three days or more, the certificate must cover the absence from its first day. The employer must receive its copy no later than the third day. The private-sector insured person must also send the CNS sheet no later than the third day, based on the postmark; when that CNS deadline falls on a weekend or public holiday, it moves to the next working day. An employer may still demand justification for an absence of one or two days.

“On the first day of absence, employees must inform their employer or the latter's representative of their incapacity for work.” — Guichet.lu

A standard certificate has three sheets: the first goes to the CNS, the second to the employer and the third is retained by the employee. Include the 13-digit Luxembourg identification number in correspondence. A late or excessively retroactive certificate can create problems, so contact the doctor promptly.

Electronic certificates do not remove the deadline

Luxembourg began gradually introducing the electronic certificate, or eCIT, in 2026. When a Luxembourg doctor uses the equipped system, the employee can consult the certificate in a private MyGuichet space and transmit it electronically to the CNS and employer. Confirmation of transmission and receipt provides evidence.

The digital option is conditional. If the doctor does not issue an eCIT, an employer cannot receive it electronically or no receipt confirmation appears, the employee must use the conventional method within the legal deadline. The CNS eCIT guidance should be checked each time rather than assuming the doctor's system completed every delivery.

An extension creates a fresh communication duty. Inform the employer on the first day work was originally due to resume. The extension certificate must reach the CNS and employer under the separate extension deadlines described by Guichet. Send it immediately and retain proof instead of calculating to the last hour.

Pay, protection and conduct during leave

For most private-sector employees, the employer continues full contractual pay until the end of the month in which the cumulative 77th day of incapacity falls within an 18-month reference period. If the leave continues, the CNS generally pays sickness benefit from the following month. The counter uses calendar days and can include separate periods; it is not simply 77 days in one illness.

First-day notice and timely delivery of the employer's certificate are concurrent conditions for special dismissal protection. That protection is not an absolute ban on every termination. Emergency hospitalisation has a specific eight-day delivery rule. Because dismissal cases turn on facts and timing, an employee facing a dispute should contact the ITM, staff representation or a lawyer quickly.

During the first five incapacity days, going out is generally prohibited, apart from documented medical visits and limited necessities allowed by the rules. From day six, if the doctor has not advised against leaving home, outings are permitted from 10:00 to 12:00 and 14:00 to 18:00. The CNS can perform checks from the first day, including for non-residents. A different place of stay must be reported.

• Notify the designated employer contact on day one and save proof.
• Get the certificate early and verify both CNS and employer delivery.
• Keep the employee copy and all electronic confirmations.
• Report an extension and any different stay address promptly.
• Follow outing restrictions even when the certificate says otherwise.

Illness on holiday and returning to work

Certified sick days during annual leave are not counted as holiday days. An employee in Luxembourg sends the certificate within the applicable period; someone abroad informs the employer as soon as possible and ensures delivery. The recovered holiday is rescheduled by agreement rather than automatically added to the trip.

After a long absence, return may require medical coordination. Current 2026 reintegration guidance says the CMSS assesses the situation after six weeks of incapacity. A phased therapeutic return is possible when its conditions are met, with the employer and CNS approvals. Cross-border workers have the same reintegration rights as residents.