Declaring an incapacity for work


Because of the reduced activity of the postal services, insured persons in France and Belgium have the possibility of exceptionally submitting their certificate of incapacity for work by email to:

Please consult our news on the subject which contains more detailed information.


As a result of the Covid-19 crisis, various measures have been taken regarding sick pay and incapacity for work benefits.


During the state of crisis, the 26-week period of protection against dismissal in the event of incapacity for work is suspended.

Employees must take certain measures if they are unable to work because of illness or accident. To be able to justify their absence from work and take sick leave, employees must submit, in a timely manner, a medical certificate issued by a physician certifying their incapacity for work and stating how long it is expected to last to their employer and health insurance fund.

A medical certificate of incapacity for work must be submitted to the CNS in the case of an absence of more than 2 working days. The employer can request a medical certificate as of the first day of absence.

The employee must:

  • send the 1st sheet of the form to the CNS;
  • send the 2nd sheet to their employer (or their representative) ;
  • keep the 3rd sheet.

Who is concerned

All persons for whom registration is mandatory, regardless of their professional status, who do not report to their place of work due to illness or accident, must declare their incapacity for work using a medical certificate.


Certain deadlines must be met to declare an incapacity for work to the CNS and to the employer.

How to proceed

Means of declaring incapacity for work

Private sector employees' or self-employed workers' obligations towards the CNS (sheet 1)

The private sector insured must send the 1st sheet of his medical certificate to the CNS by no later than the 3rd day (postmarked) of his incapacity for work. If the deadline falls on a Saturday, Sunday or public holiday, it is extended to the next working day.

The medical certificate of incapacity for work must be established no later than the 3rd day of incapacity for work or its extension. These procedures should also be followed when employees are on leave.

Employees who fail to submit their medical certificates to the CNS in time may be subject to a fine.

Employee's obligations to their employer (sheet 2)

On the first day of absence, employees must inform their employer or the latter's representative – orally or in writing (e-mail, fax or text message), either personally or through an intermediary – of their incapacity for work. In addition, the medical certificate (Sheet 2), certifying the incapacity for work and how long it is expected to last, must be delivered to the employer or the latter's representative by no later than the third day of absence.

For example, a worker who is unable to work on Tuesday must inform the employer on the same day as soon as possible, and the certificate must be delivered to the employer no later than Thursday.

If employees cannot be sure that their employer will receive their certificate in time by post (when they are abroad, for example), they should send it by other means.

These procedures should also be followed when employees are on leave. In this case, the leave is interrupted by the illness:

Cross-border workers may be issued a certificate of incapacity for work by a physician in their country of residence.

For French cross-border workers, the French certificate of incapacity for work ( Avis d'arrêt de travail) has 1 part which has to be sent to the National Health Fund, as well as another part which is for the employer.

For German cross-border workers, the German certificate of incapacity for work ( Arbeitsunfähigkeitsbescheinigung) has 1 part which has to be sent to the National Health Fund, as well as another part which is for the employer.

For Belgian border workers, the majority of certificates have only one part. It is therefore necessary to ask the doctor for a duplicate for the attention of the employer.

The 13-digit Luxembourg national identification number must be indicated in each correspondence.

Obligations to the National Employment Agency (ADEM) (sheet 2)

If unemployed residents are unable to work due to illness or accident, they must inform their ADEM guidance counsellor and send the latter a certificate of incapacity for work.

No addition, annotation, deletion, alteration or supplementation of data may be made by the beneficiary or by a third party in the sections of the form reserved for the doctor, at the risk of incurring sanctions and invalidating the certificate.

Permission to go out during incapacity for work

Persons on sick leave may not go out during the first five days of incapacity for work (despite any indication to the contrary on the medical certificate of incapacity for work). From the 6th day of sick leave (if leaving home has not been advised against by the medical practitioner), the worker is allowed to go out between 10.00 and 12.00 and between 14.00 and 18.00 (even if this is not specified on the medical certificate of incapacity for work). In case of non-compliance, the CNS can issue warnings and/or fines.

A person on sick leave may not:

  • join in sports activities (unless medically indicated);
  • carry out any activity which is not compatible with his state of health;
  • go to a drinking or eating establishment, except to have a meal (as from the first day of incapacity for work) and provided the person has previously informed the National Health Fund (CNS) using the specific form, or by phone, fax or email.

The person on sick leave must provide the relevant health fund with their name and first name, and the exact address (place, street, number, floor, etc.) where he or she will be staying during the period of incapacity for work. If said address is different from the home address, it must be specified on the medical certificate of incapacity for work, or failing this, be communicated to the CNS by phone, fax or email. Similarly, persons on sick leave staying with a third party have to indicate the name and first name of said third party including the duration of their stay.

Essential visits for a medical check at the social security (Contrôle médical de la sécurité sociale - CMSS) or with the attending physician or any other health practitioner are allowed at any time but must be documented by the worker on sick leave.

The administrative check carried out by the CNS is a measure to verify whether the person on sick leave is actually at home. The check can take place between 8.00 and 21.00. These controls can concern both resident and non-resident workers and may be carried out as from the first day of incapacity for work.

During the administrative control, a statement of presence or contravention is drawn up. If the worker is found to be absent during the administrative check, the inspector will leave an administrative check notice. The worker on sick leave must then provide an explanatory note explaining the reasons of his absence within 3 days of the administrative check.

Going abroad during incapacity for work

A stay abroad during an incapacity for work can be allowed by the CNS in case of serious illness and only in these cases (e.g.: cancer, stroke, severe heart failure, sclerosis, etc.):

  • upon prior request;
  • for a set period;
  • on the concurring advice of the attending physician and the CMSS.  

Persons authorised to receive palliative care may be allowed to reside abroad for as long as they receive palliative care if a written request is sent to the CNS in advance.

Finally and always on prior request, the CNS can allow a stay abroad for a maximum of one working week, on advice of the attending physician and exclusively in the following cases:

  • observation of a consolidated illness in the context of invalidity proceedings;
  • death abroad of a parent or relative of the first degree or spouse or partner;
  • birth abroad of a child of the person declared unable to work.

Applications for authorization to stay abroad must be sent to the relevant department of the CNS within a minimum of 3 weeks before departure, except in the case of death or birth.

Applications for permission to stay abroad must be sent to:

Caisse national de santé
Services Contrôle et gestion des certificats d’incapacité de travail
L-2978 Luxembourg

Determining rate of pay to employee during incapacity for work

Employees (excluding those employed in the employer's household) and government workers

In the event of incapacity for work due to illness, employees in the private sector must:

  • continue to be paid by their employer until the end of the month in which the 77th day of incapacity for work occurs, during a reference period of 18 consecutive months;
  • and, where applicable, receive sickness benefit, starting in the month following the 77th day of illness; The sickness benefit will be paid by the CNS.

During the period in which the salary is maintained, the employer must comply with all clauses of the employment contract, since employees who are unable to work are entitled to the full salary and other benefits due to them under their employment contract, including any commission provided for in the contract.

Self-employed workers

The general principles that apply to employees are also applicable to self-employed beneficiaries.

The financial benefit granted to self-employed workers is suspended until the end of the month in which the 77th day of incapacity for work falls, during a reference period of 12 consecutive calendar months. The financial benefit is suspended again at the beginning of the month following the one in which that limit is no longer reached.

There is a difference between employees and non-employees with regard to the opening of the right to sickness benefit:

  • employees: 18 month reference period;
  • non-employees: 12 month reference period.

For self-employed workers voluntarily affiliated with the Employers' Mutual Insurance Scheme (Mutualité des employeurs - MDE), the latter ensures, during the period of suspension of the financial benefit, the payment of financial indemnities.

Domestic workers employed in the employer's household

For insured persons employed in the employer's household (cleaning women/men, private persons providing care or care of dependent persons, etc.), the financial benefit is calculated on the basis of:

  • the number of hours during which the insured meets the conditions for the granting of the financial benefit;
  • the hourly wage used for the calculation of the social contributions for the previous month.

Government employees (civil servants, public and municipal employees)

Government employees are entitled to continued compensation for the entire duration of their sick leave.

Progressive return to work

The request for a progressive return to work has to be made by using the standardised form "Demande de reprise progressive du travail pour raisons thérapeutiques", on which the attending physician will attest that a progressive return to work for therapeutic reasons will improve the insured person's state of health.

The form has to be duly completed and signed by the attending physician and is subsequently submitted to the employer who has to give their consent.

In order to benefit from progressive return to work, the employee is required to:

  • have been unable to work for at least one month out of the 3 months preceding the request, and;
  • be unable to work at the time of the request.

The progressive return to work for therapeutic reasons may only begin once the CNS has given its consent, based on a reasoned opinion from the Medical Board of the Social Security.

The return to work as well as the work carried out must be recognised to have a beneficial effect on the employee's state of health and be attested by the attending physician.

Financial benefits are due throughout this period.

The insured must present medical certificate attesting a full-time (100%) incapacity for work during the entire period. The insured person is deemed to be unable to work.


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En poursuivant votre démarche, vous acceptez que vos données personnelles soient traitées dans le cadre de votre demande.

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