Social Security Medical Check in Luxembourg

A medical certificate is mandatory for any sick leave, issued by a doctor in France or Luxembourg. It is important to send the original to the CNS before the end of the third day of incapacity (by registered mail or electronically), including your 13-digit CNS registration number, and a copy to your employer. The employer must also be informed on the first day, under penalty of salary suspension.

Your employer or the CNS may request an administrative or medical check at your residence in France, between 8:00 a.m. and 9:00 p.m., from the first day of absence, without prior notice, except during authorized outings. You must provide your exact residence address. The Social Security Medical Check (CMSS) will validate or invalidate the sick leave.

During the first five days, no outings are allowed, except for medical reasons (doctor, pharmacy, CNS check). From the 6th day, if explicitly authorized by the medical certificate, outings are allowed from 10:00 a.m. to 12:00 p.m. and from 2:00 p.m. to 6:00 p.m. Luxembourg rules take precedence over any foreign certificate.

If absent during a check but within an authorized outing window, the employee receives a notification with a response request. They have 3 working days to provide written justification (e.g., medical certificate or proof of permitted activity). Valid justification prevents sanctions.

Without justification within 3 days, the CNS imposes an administrative fine (up to €750 for repeat offenses) and suspends daily sickness benefits (IJ). The employer may consider this gross misconduct, potentially resulting in a warning, formal notice, or immediate dismissal, without protection against termination. Repeated absences strengthen the grounds for dismissal.

If deemed fit, the CMSS does not confirm incapacity to work, and the employee must return to work on the date specified in the decision. In this case, sickness benefits (IJ) are immediately suspended. The cross-border worker must resume their position or face sanctions, such as unjustified absence, which may lead to dismissal or loss of salary for days not worked from the date of fitness indicated.

An appeal can be filed with the Arbitral Social Security Council (CASS) by a simple written request within 40 days of the decision notification. This procedure is free and does not require a lawyer but has no suspensive effect: the CNS decision remains enforceable during the process. The employee must therefore return to work.

Consequences if the Appeal Succeeds
If the CASS overturns the CNS fitness decision, sickness benefits (IJ) are retroactively reinstated from the day of the contested decision, covering the period of unjustified suspension. Any dismissal due to absences may also be annulled, with protection against dismissal for 26 weeks during the procedure.

Consequences if the Appeal Fails
If the appeal fails, the employee cannot receive salary from the fitness date if they did not report to work. They also risk dismissal for unjustified absence, considered gross misconduct. This dismissal allows the employee to claim unemployment benefits in France, subject to other general eligibility conditions, but does not allow for severance pay or notice periods. The contract may end immediately.