Telling the employer on day one, the certificate by day three, who pays the salary and for how long, the protection against dismissal: the employer's guide to an employee's incapacity for work.
In short. When an employee is off sick in Luxembourg, they must tell their employer on the first day and hand over a medical certificate by the third day of absence at the latest. The employer then keeps paying the full salary until the end of the month in which the 77th day of incapacity falls, over an 18-month reference period; beyond that, the National Health Fund (CNS) takes over. The Employers' Mutual Insurance refunds the employer 80 % of what was advanced. During that time, the employee is protected against dismissal, up to a limit of 26 weeks. A cross-border employee follows the same rules.
An employee falling ill is an everyday event, and yet a minefield for an employer: from when is a certificate needed, who pays the salary and for how long, can you dismiss someone who is off, what to do with a cross-border worker treated on the other side of the border. The rules exist, they are precise, and improvising them is expensive. Here, for an SME owner, is how incapacity for work works in Luxembourg: the employee's obligations, the salary mechanics, the protection against dismissal and the payroll treatment.
What counts as incapacity for work in Luxembourg?
Incapacity for work, what people commonly call sick leave, is an employee's inability to do their job for health reasons, confirmed by a doctor. It brings in three players: the employee, who must give notice and justify the absence; the employer, who keeps paying the salary first; and the National Health Fund, which takes over beyond a certain threshold. Knowing who steps in when is the key to handling an absence, short or long, without a misstep.
Giving notice and proof: the employee's obligations
The rule comes down to two deadlines. The employee must tell their employer on the first day of absence, as soon as possible. That notice can be spoken or written, by phone, email, text or fax, given by the employee or by a third party. Telling a colleague is not enough, unless that colleague passes it on.
Next, the employee must hand over a medical certificate of incapacity by the third day of absence at the latest. The certificate comes in three parts: the first goes to the CNS, the second to the employer, the third stays with the employee. For an urgent hospital admission, the deadline is extended to 8 days from admission.
| Deadline | What the employee must do |
|---|---|
| On the first day | Tell the employer of the absence, by any means |
| By the third day at the latest | Hand the medical certificate (employer part) and send it to the CNS |
| Urgent hospital admission | Send the certificate within 8 days |
A useful point for SMEs: for an absence of one or two days, company practice may exempt the employee from producing a certificate, while the employer stays free to ask for proof of the absence. The electronic certificate of incapacity (eCIT) is becoming the norm, with the doctor sending the sick note directly. Where the doctor practises abroad and electronic transmission is not possible, the certificate must be sent by the usual means, within the legal deadlines.
Who pays the sick employee, and for how long?
Contrary to a common belief, the health fund does not pay the employee on sick leave straight away: the employer does, first. The law requires continued remuneration, meaning the full salary is kept up, until the end of the month in which the 77th day of incapacity falls, over a reference period of 18 successive months. The 77 days are counted as calendar days, not working days, and the counter mixes the different absences in the period.
Once that threshold is crossed, from the 1st of the following month, the CNS takes over and pays the cash sickness benefit for as long as the incapacity lasts. That benefit cannot be lower than the social minimum wage or more than five times it, and it does not cover overtime, occasional bonuses or benefits in kind. If the employee changes employer, the 77-day counter restarts at zero with the new one.
| Period | Who pays the employee |
|---|---|
| From day 1 up to the 77th day (over 18 months) | The employer, keeping the salary up until the end of the month of the 77th day |
| From the month after the 77th day | The CNS, through the cash sickness benefit |
| After 26 weeks, if the contract continues | The CNS, with the employer topping up to net salary during the first 12 months of incapacity |
This salary advance is a real cost for the company, and that is exactly what the Employers' Mutual Insurance cushions: it refunds the employer 80 % of the continued pay and the related employer charges, even 100 % in certain cases such as the trial period. We cover that mechanism, its contribution classes and its effect on your cash flow in our dedicated piece on the Employers' Mutual Insurance in Luxembourg.
Protection against dismissal during sick leave
This is the point that worries both sides most. Once the employee has met their obligations, namely giving notice on the first day and sending the certificate by the third at the latest, they are protected against dismissal for the whole duration of their incapacity, up to a limit of 26 weeks from the start of the absence. During that period, the employer cannot notify them of dismissal.
That protection has limits worth knowing. It does not apply if the certificate was not sent in time, nor where the employer had already started the procedure, for example by calling the employee to the preliminary meeting or handing over the dismissal letter, before being informed of the incapacity. It also ends in specific cases, such as incapacity resulting from a crime or offence committed deliberately by the employee. And beyond the 26 weeks, dismissal becomes possible again. The notice periods, the procedure and the severance pay are set out in our guide to dismissal in Luxembourg.
Outings, checks and the cross-border case
During the absence, the employee stays bound by outing rules set by the CNS, and may be subject to an administrative or medical check meant to verify the reality of the incapacity. Breaking those rules can cost them their benefit, and give the employer grounds to challenge the absence.
The cross-border employee is bound by exactly the same obligations: notice to the employer on the first day, certificate by the third at the latest. The CNS can ask the fund in the country of residence, for instance the CPAM for a worker living in France, to arrange a home check. If the employee is abroad when the absence begins, they must tell their employer as quickly as possible. Nationality or place of residence change nothing about the deadlines: they are the same for everyone.
A long absence in your team and you are unsure who pays what, or where the Mutualité refund stands? We will put your payroll back in order.
Review your payrollWhat sick leave changes for your payroll and your books
A work stoppage is not just an HR matter, it is also a payroll and accounting mechanism that is handled badly by hand. Three movements need steering. First, the salary advance by the employer, then the tracking of the Mutualité refund, file by file, so the money actually comes back into your cash flow. Next, the switch from employer to CNS at the 77th day, which changes the nature of what flows through the payslip. Finally, the impact on your result and your cash flow, which deserves to be read when the absence happens, not several months later.
This is the whole point of payroll linked to the accounts: the entries of an absence, the benefit, the refund expected, flow into your books as they happen. We explain the logic of payroll outsourcing in our guide to outsourcing payroll in Luxembourg, and the payslip read line by line in our piece on the Luxembourg payslip. To gauge what an employee really costs, charges included, see our calculation of the real cost of an employee in Luxembourg.
Frequently asked questions
How quickly must you tell your employer you are ill?
The employee must inform their employer of the incapacity on the first day of absence, by any means. They must then send a medical certificate by the third day of absence at the latest, the deadline being extended to eight days for an urgent hospital admission.
Who pays a sick employee in Luxembourg?
The employer keeps the salary up until the end of the month in which the 77th day of incapacity falls, over an 18-month reference period. Beyond that, the National Health Fund pays the cash sickness benefit. The Employers' Mutual Insurance then refunds the employer 80 % of the continued pay.
Can you dismiss an employee on sick leave?
No, in principle. Once the employee has told the employer on the first day and sent the certificate by the third at the latest, they are protected against dismissal during their incapacity, up to a limit of 26 weeks. That protection falls away if the deadlines were missed or if the dismissal procedure was already under way before the employer was informed.
Is a medical certificate needed for a one or two-day absence?
Not necessarily. Depending on company practice, the employee may be exempt from a certificate for a one or two-day absence, but they must still tell their employer, who stays free to ask for proof of the absence.
Does a cross-border sick employee follow the same rules?
Yes. The cross-border worker must inform their employer on the first day and send the certificate by the third at the latest, like a resident. The CNS can have a home check arranged by the fund in their country of residence.
Read on
- The Employers' Mutual Insurance in Luxembourg: what it refunds your business
- Dismissal with notice in Luxembourg: notice periods and severance pay
- Paid leave in Luxembourg: 26 days, accrual and carry-over
- What an employee really costs in Luxembourg in 2026
- Accounting firm in Luxembourg: the complete guide for an SME
Why Advena?
We keep the accounts and payroll of Luxembourg SMEs of 1 to 50 employees inside the management tool we deploy ourselves, on a fixed fee from 325 € per month, all in. On a sick leave, that means three concrete things: we handle the switch from continued salary to the CNS benefit at the right moment, we track the Employers' Mutual Insurance refund file by file so it comes back into your cash flow, and these movements feed straight into the Odoo where we keep your books, in real time. You see the effect of a long absence on your position when it happens, not eight months later. We inform on the rules; for an individual situation, the CNS statement stays the reference.
Accounting, VAT, annual accounts and payroll in a single fee announced upfront. Let's talk about your file.
Request your fixed feeInformation current as of October 2026, based on the rules published by Guichet.lu on the medical certificate and the continuation of remuneration, and by the National Health Fund. As these rules can change and every situation is specific, this article is informational and not individualised legal, tax or social advice.
