Employee's declaration of incapacity

Dealing with incapacity for work can be a challenging and stressful experience.

To support me during this time, the CNS has created this online section to simplify the declaration process and offer valuable assistance throughout my illness.

If I am self-employed or employed in a private household, I consult the page 'My incapacity for work if I am self-employed or employed in a private household'.



Everything I need to know

My declaration if I live in Luxembourg

I must use the form/certificate issued by my doctor. It consists of three separate sheets and contains:

  • My 13-digit identification number;
  • The start and end dates of my incapacity for work;
  • The diagnosis code;
  • The date on which the certificate was produced;
  • The prescribing doctor's stamp or signature.

Good to know: my 13-digit identification number is made up as follows: YYYYMMDD for the year, month and day of birth, and XXXXX which are my five personal digits.

  • I send the first sheet (original) to the CNS, either using the online declaration form or by post.
  • I send the second sheet to my employer.
  • I keep the third sheet.

For more information, click on : My obligations towards my employer in the event of incapacity for work.

My declaration if I am a cross-border worker

My 13-digit identification number issued in Luxembourg must appear on the certificate of incapacity for work. If it has not been written down by the doctor, I can add it.

Please note! If I enter my own identification number on the certificate of incapacity for work, I must be careful not to use the sections reserved for the doctor. Any changes or additions to these sections are unauthorised and may result in penalties and the invalidity of the certificate (see the tab 'Sanctions').

My doctor may not provide me with a certificate as issued in Luxembourg.

  • If I live in France, the doctor will issue a certificate consisting of section 1 for the health insurance scheme and section 2 to be sent to my employer.
  • If I live in Germany, where the electronic certificate (eAU) is in force, I ask the doctor to provide me with a printed copy of the certificate, which I send to the CNS, either using the online declaration form or by post.
  • If I live in Belgium, where most certificates have only one section, I ask the doctor to provide me with a duplicate, which I send to my employer.

I send my sick leave to the CNS either using the online declaration form or by post. 

What is the deadline for notifying the CNS of my incapacity for work?

If my incapacity for work does not exceed 2 workdays, I do not need to notify the CNS.

If I am off work for 3 days or more, I must send my certificate of incapacity by the end of the 3rd workday of incapacity for work at the latest, as evidenced by the postmark, whether I am at my usual place of residence or abroad when I fall ill.

Retroactivity of the certificate of incapacity for work

The medical certificate must be issued no later than the third day of incapacity for work or its extension. It may therefore have a retroactive effect of up to two days. Beyond this, it will only be taken into consideration by the CNS from the date it is issued.

For example, if I fall ill on a Monday and cannot see my doctor until Wednesday, my doctor will be able to draw up my sick leave from Monday. The entire period of incapacity for work will then be taken into account.

On the other hand, if I do not consult until Thursday and my doctor draws up my sick leave from Monday, the CNS will consider that I have been unable to work since Thursday.

What should I do if my incapacity for work is extended?

If my doctor extends my incapacity for work, I must send the new certificate to the CNS before the expiry of the second workday following the date initially scheduled for my return to work.

Here are a few practical examples to help me see things more clearly: Calculating the deadline for my declaration

If my incapacity starts on a Monday, I must send my certificate to the CNS by Wednesday at the latest (3rd workday following the start of my incapacity).

  • Part-time employment

If, as a part-time employee, I do not work on Mondays and I fall ill on a Monday:

→ I notify my employer on my first day of absence, i.e. on Tuesday, and send my certificate to the CNS by Thursday at the latest.

  • Non-workdays

If my incapacity for work starts on a Friday, and Saturday and Sunday are non-workdays:

→ I send my certificate to the CNS by Tuesday at the latest.

  • Extension

For an extension, if my first certificate indicated incapacity until Tuesday and therefore a return to work on Wednesday:

→ I send my new certificate no later than Friday (2nd workday following the planned day of my return to work).

  • Extension and non-workday

If the last possible day for sending the extension is a non-workday (Saturday, Sunday or public holiday), the deadline is extended to the next working day.

→ So, if I was initially due to return to work on a Friday, the 2nd following day being a Sunday, the deadline is extended to the next working day, i.e. Monday. I therefore send my extension by Monday at the latest.

How do I declare my incapacity for work to the CNS?

Online

I use the 'Declaration of incapacity for work to the CNS' form.

I click here to access the form for declaring my incapacity for work

By post

I send my certificate of incapacity for work by post to the following address (without postage from Luxembourg):

  Caisse nationale de santé
  Indemnités pécuniaires
  L-2980 Luxembourg

What are the penalties imposed?

Failure to submit a certificate of incapacity for work

If I fail to send my certificate of incapacity for work to the CNS, the latter will send me a letter asking me to fulfil my obligation. Important! In the event of a repeat offence, the CNS may, under article 447 of the Social Security Code, impose a fine of up to €750.

Falsifying a certificate of incapacity for work

Warning! Any suspect certificate is reported for investigation by the CNS department responsible for processing medical certificates to the department dedicated to combating abuse and fraud.

Good to know: any modification of the data in the sections reserved for the doctor, by the insured or by a third party, exposes the latter to a fine, the invalidity of the certificate and the reporting of the events to the State Prosecutor.

The certificate is null and void in all cases. However, the amount of the fine depends on the seriousness of the offence:

  • Modification of data relating to a period of less than or equal to three days of incapacity for work: 200 euros
  • Modification of data involving more than three days' incapacity to work: 500 euros
  • Repeat offence, regardless of the length of time involved: 750 euros

How to send my certificate of incapacity to the CNS?

Contact us

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