Member State of the EU, the EEA and Switzerland

Important: In the context of the COVID-19 pandemic, insured persons who have a planned treatment abroad that has to be postponed are requested to inform us of the new date by e-mail to (to be used only for requests relating to transfer abroad, not for submitting other certificates). We will then send you a new coverage certificate by post.

A prior authorisation from Luxembourg is required for inpatient hospital care or outpatient care if health care is provided, using highly specialised medical equipments (included in the list of treatments subject to prior authorisation) in a Member State of the EU, the EEA (Iceland, Liechtenstein, Norway) and Switzerland.

Types of authorisation

Upon presenting a request for prior authorisation issued by a doctor and following a favourable opinion from the Medical Board of the Social Security (CMSS), two types of authorisations are possible.

S2 Authorisation

If the request concerns a contracted (non-private) establishment or hospital in the country, where treatment is provided,  the insured person receives a S2 form, provided for by regulation 883/2004. After a favorable opinion from the CMSS, this form is issued by the CNS and certifies the right to planned treatment in another European Union Member State, Iceland, Liechtenstein, Norway or Switzerland.

The dates of validity, the type of treatment requested by the prescribing doctor and the name and precise address of the foreign establishment or provider are given on the S2 form.  

Directive 2011/24 Authorisation

Coverage can take place under the terms of directive 2011/24/EU on the application of patients' rights in cross-border healthcare. The provisions of the directive apply, if an S2 form cannot be issued, usually because the treatment is provided in a private institution or the insured person chooses to apply the provisions of the directive. Again, in case of agreement, the certificate of coverage is valid only for the specific establishment indicated on the request.

For outpatient health care, prior authorisation is not necessary, unless highly specialised and costly hospital infrastructure or medical equipments are used.

Procedure for requesting authorisation

A request for prior authorisation duly completed and medically motivated by a doctor (general practitioner or specialist / with a practice in Luxembourg or abroad) must be submitted to the CNS before the planned treatment begins. It is recommended to make the request at least 2 weeks before the planned treatment. The doctor must state the medical reasons why treatment is impossible or inappropriate in Luxembourg. The procedure for requesting authorisation remains the same for both types of authorisation, S2 authorisation and directive 2011/24.

The request can be submitted by mail or e-mail (, pdf format) to the "Service Transfert à l'étranger". After checking the administrative conditions, the CNS will forward the file to the Medical Board of Social Security (CMSS) for its opinion. Based on the opinion of the CMSS, the CNS will decide whether or not to cover the costs.

A prior request is not sufficient for the cost coverage! Prior authorisation is required.

Without prior authorisation, the CNS will not be able to reimburse costs.

Period of validity

The S2 is valid for the period mentioned on the form. In general, the validity period corresponds to the duration requested by the prescribing doctor, which is the basis on which the CMSS gives its opinion. If necessary, an extension may be requested by the patient's doctor for sound medical reasons.

A renewal can be requested by the patient's doctors, under the same terms as the initial request.

Practical information  

Information abroad

It is not clearly defined whether the foreign service provider offering the treatment is required to accept the S2 form. It is therefore advisable to ask the specialist centre abroad beforehand, whether they agree to accept the S2 form and to carry out the formalities required in relation to the legal health insurance fund abroad. If the specialist centre does not carry out these formalities, you will have to ask a local health insurance fund of your choice about the procedure to follow with the S2 form.

For treatments which involve highly specialised medical equipments or other treatments subject to special authorisation procedures involving the health insurance fund in the country of treatment, it is important that the S2 form and the request for authorisation to cover the medical care are submitted to the foreign health insurance fund for approval. In general, the specialist centre abroad ensures that the procedures are complied with.

Refusal of the S2 abroad

If the provider refuses coverage based on the S2, the insured person must pay the invoice and request a refund. In the case of inpatient treatment, approved centres should invoice the treatment directly to the insurer in the country of treatment. Foreign service providers may sometimes request a coverage form, issued by this local health insurer. This is why it is important to check with the foreign clinic beforehand.

In the case of inpatient treatment, if the insured person receives an invoice for the full cost from from the establishment even though they received an S2 form, it is advisable to contact the establishment and try to arrange direct coverage via the S2 form.

Terms of coverage

S2 Authorisation

Upon presenting the S2 form to the health insurance institution in the country where the treatment will be provided, the insured person will receive healthcare under the same conditions and at the same rates as people insured in that country. The treatment covered by the authorisation is thus paid for, according to the conditions and tariffs in the country where it is provided. The S2 form does not guarantee full coverage of the medical costs incurred. In the ideal case, it enables cover for the treatment costs through the third-party payment system via a local health insurance fund in the country of treatment.

If the third-party payment system does not apply, reimbursement is provided for at the rates of the treatment country by the health insurance institution in the country of treatment. If specifically requested, an additional refund may be applied for, from the competent fund in Luxembourg.

For example, fee supplements and other personal arrangements are not covered (e.g. Chefarztbehandlung, Wahlleistungen, supplement for a room with one bed or two beds, etc.).

The insured person can request an additional refund from the competent insurer. If the costs payable by the insured person, excluding any supplements, are higher than the costs theoretically payable in their competent country, the insured person will receive the difference within the limit of the reimbursement rates and tariffs in the competent country.

Directive 2011/24 Authorisation

With an authorisation under directive 2011/24, healthcare is covered at the rates and tariffs of the competent country. If authorisation is granted, the insured person receives a certificate of coverage (titre de prise en charge) explaining the reimbursement terms (costs to be advanced, reimbursement to be requested from the competent fund in Luxembourg, according to the tariffs or fixed amounts specified).

Given that the costs invoiced may be high, and far higher than the amount refunded by the fund in Luxembourg, the insured person is advised to ask the specialist centre abroad for a quotation for the treatment costs.

In this case, the insured person pays the costs of the treatment in full and is refunded by their competent fund in Luxembourg according to the conditions and tariffs applicable in Luxembourg.

Appealing a refusal

If authorisation is not granted, the parties may send a written objection to the Council of Administration of the CNS, within forty days of receiving the decision.

To be valid, the objection must be signed by yourself, your legal representative or your proxy. The proxy may be a lawyer or a representative of a professional association or trade union, of which you may be a member and must have a special written power of attorney.

It is advisable to send the objection by registered post to the address of the Council of Administration of the CNS.


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