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.

Digitisation, from issuing to sending

Sick notes will soon be issued in a 100% electronic format by doctors. In practical terms, if your doctor and your employer are technically ready, you will be able to send your medical certificate electronically to the CNS and your employer.

More information can be found under ‘Digitisation of medical certificates’ below.

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, I click on: My obligations towards my employer in the event of incapacity for work (guichet.lu).

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.

Fake certificates of incapacity for work

I must be careful about certificates of incapacity for work (CIT) that may be purchased on online platforms, without consultation or assessment by a doctor.

The CNS rejects all certificates purchased online without any personal contact with the doctor or issued by unknown doctors. In such cases, no benefit will be paid to me, and my employer will be informed.

If I use such a certificate, I risk not only sanctions linked to my employment contract, but also a fine and legal proceedings initiated by the CNS. I should therefore make sure that I always obtain my certificates from my trusted doctor.

As of today, the following doctors are unknown:

  • Umar Masroor
  • Samueel Zubair
  • Haresh Kumar
  • Ahmad Abdullah
  • Sahar Rezgani
  • Imen Missaoui
  • Harbel Lakhder

Digitisation of medical certificates

Soon, medical certificates will be available in electronic format. If your doctor and employer are technically ready, you will be able to send your medical certificate electronically to the CNS and your employer.

Find out below the steps to follow and the essential information you need to use the electronic certificate.

All the steps I need to take to benefit from digital delivery

How do I activate the digitisation of medical certificates?

  1. Create a MyGuichet.lu personal eSpace
  2. Receive my electronic medical certificate automatically
  3. Send it to the CNS and my employer

What are the advantages?

  • Secure and authentic: Your data is protected
  • Fast and efficient: No more delays or lost documents
  • Environmentally friendly: Less paper, less travel

I am consulting a doctor practising in Luxembourg

Soon, my doctor in Luxembourg will be able to issue an electronic medical certificate.

As soon as the certificate is available, I will receive a notification. I will then be able to send it electronically to the CNS and my employer from my MyGuichet.lu account.

Sending to the CNS

I will have the choice between:

  • Automatic transmission: each electronic medical certificate will be sent directly to the CNS. However, I will have a short period of time to cancel the transmission before it is processed.
  • Manual transmission: I will validate the transmission of each electronic medical certificate myself from my MyGuichet.lu account.

In all cases, I will receive a confirmation of receipt from the CNS.

Sending to my employer

I can send my medical certificate to my employer: · electronically, or by post/hand delivery:

  • Direct electronic transmission to my employer's professional eSpace on MyGuichet.lu (if they have one): 
    First, I will receive a confirmation of transmission (which can be downloaded) I will also receive a confirmation of receipt as soon as my employer has viewed the certificate.
  • Postal delivery or hand delivery of the certificate: I can print the certificate myself by downloading the PDF version available in my MyGuichet.lu account. This document includes a GouvCheck code that allows my employer to check its authenticity online for free.
    My doctor can also print and sign the certificate of incapacity for work if I ask them to.

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

Certificate from a doctor practising in Luxembourg

Electronic submission

If I have not opted for automatic submission of electronic medical certificates, I will log in to MyGuichet.lu as soon as I receive notification that my electronic certificate is available. I will then submit my certificate (section 1 with diagnosis) to the CNS. I will receive confirmation of receipt after submitting the certificate.

Certificate from a doctor practising abroad

Traditional submission

For medical certificates issued by a doctor abroad, electronic submission is not possible. In this case, I will submit the certificate in the traditional manner.

Frequently asked questions (FAQ)

I would prefer to receive my certificate in paper format. Is this still possible?

Yes.

At my request, the doctor must print and sign the certificate of incapacity for work.

I can then send it to the CNS and my employer by post.

My employer has not read my electronic medical certificate. What should I do?

If, after my initial submission via MyGuichet.lu, my employer has not read my electronic sick note, I will send a printed version of the note directly to ensure that I comply with the legal deadline for reporting my absence.

Alternatively, I can resubmit the note to my employer via MyGuichet.lu.

I am unable to send my electronic sick note to my employer via MyGuichet.lu. Why is this?

I log in to my personal eSpace on MyGuichet.lu and in the 'Certificate of incapacity for work' section, my employer's name is not displayed: I only see the term 'Employer' and the 'Send' button does not appear.

The system only allows certificates to be sent to employers who are identified via MyGuichet.lu in their professional eSpace. If my employer does not have a professional eSpace on MyGuichet.lu, I will not be able to send the certificate digitally from my MyGuichet.lu eSpace.

In this case, I must send them a printed version of the certificate within the legal deadline.

If I have several employers, I may only be able to send my electronic certificate to some of them.

Can I view my old electronic medical certificates?

Yes.

I will be able to view the history of my electronic sick notes at any time in my personal eSpace on MyGuichet.lu.

Each certificate will be archived there with the date of issue, the period covered and the transmission status.

This only applies to sick notes generated electronically by my doctor from January 2026 onwards, if applicable.

My doctor made a mistake on my electronic medical certificate. What should I do?

I must contact my doctor so that they can cancel the electronic sick note from their software. I will receive a notification following this cancellation.

My doctor can then issue a new, corrected electronic sick note.

How to send my certificate of incapacity to the CNS?

Contact us

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