Frequently asked questions (FAQ)

Is prior authorisation needed to consult a doctor in a EU Member State?

No, for consultations with a doctor (in a foreign health centre, clinic or hospital) you do not necessarily need prior authorisation. The reimbursement is made according to Luxembourg rates and tariffs. It is important to remember that no reimbursement will be made if the terms specified by the CNS statutes are not respected.

However, authorisation is required if the doctor uses highly specialised medical equipment specified in the restrictive list (tableau des équipements et appareils soumis à planification) or the consultation requires the use of hospital infrastructure.

Prior authorisation can still be applied for if a prescribing doctor directs the patient to a colleague abroad. In this case, the procedure for requesting prior authorisation should be respected.

If prior transfer authorisation is granted, the insured person is entitled to request a travel allowance, which is not the case without prior transfer authorisation.

I would like to travel to a EU Member State, Switzerland, Iceland, Liechtenstein or Norway for treatment. What rules do I need to observe?

The conditions of cover depend on whether the care you want to receive abroad will be administered on the basis of an authorised treatment/transfer or not.

1. There are certain types of treatment that can only be provided abroad if prior authorisation is given. The treatments that require prior authorisation from the competent country are:

  • inpatient treatment (at least one night in hospital)
  • treatment requiring the use of hospital infrastructure
  • treatment requiring highly specialised medical equipment
  • treatment subject to APCM (prior authorisation from the CMSS)
  • ...

2. In the case of outpatient treatment that does not require prior authorisation (e.g. doctor's surgery, single consultation with a specialist doctor in a foreign health centre or clinic etc.), reimbursement is possible without prior authorisation according to the tariffs in the competent country on presentation of the paid invoices.

What form does an authorisation for treatment/transfer abroad take?

There are two types of authorisations for a transfer abroad:

S2 agreement

The S2 form is governed by the regulations (EC) 883/2004 and (EC) 987/2009. It is issued in the case of a positive opinion from the CMSS and enables cover at the tariffs of the country where treatment is provided. In the best case, cover can be provided in the treatment country through the third-party payment system. If specifically requested, an additional refund may be applied for in the competent country (Luxembourg).

Given that the invoicing/reimbursement of treatment abroad may be different from invoicing/reimbursement in Luxembourg, it is important to remember to complete all the formalities with a possible additional fund (copies of the request + CNS S2 authorisation).

Authorisation based on article 20 of CSS

Following transposition into Luxembourg Law of directive 2011/24.  

With a directive agreement, you pay the costs of the treatment in full and are refunded by your competent fund in Luxembourg according to the conditions and tariffs in force in Luxembourg. If authorisation is granted, the insured person will receive 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 costs of the treatment.


The procedure for requesting authorisation remains the same for both types of authorisation.

In the case of inpatient treatment or any other treatment that requires prior authorisation, no reimbursement will be made without an S2 or a directive agreement.

What is the S2 form?

This form certifies your right to planned treatment abroad. With the S2 form, you can expect the same conditions of cover at the same rates as people insured in the country of treatment. 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.

How is authorisation obtained for treatment/transfer abroad?

Authorisation must be requested from the CNS before the planned treatment begins. The application is made based on a written, reasoned request from a doctor. The authorisation of the CNS, with a favourable opinion from the CMSS, is required in order to claim a refund later. Each request is evaluated in administrative and medical terms and the insured person is notified of the decision.

There is a standard form which doctors use to make the request. This form "demande d'autorisation préalable d'un transfert à l'étranger" is defined by annex L of the CNS statutes. The request can be sent to the CNS by post, fax or e-mail or submitted in person to CNS desk 14 in Hollerich.

What is the validity period of the S2 form? Can it be renewed? If so, under what conditions?

The S2 is valid for the period mentioned under point 2.3.1 of 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.

If authorisation for a transfer abroad is granted, what do I do with the S2 form? Who do I give it to?

It is not clearly defined whether the foreign doctor 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.

If consultations or outpatient examinations are all that is required, you can also advance the costs yourself and apply for a reimbursement from your insurer in Luxembourg.

For treatments that use highly specialist medical equipment 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 will take care to comply with the procedures.

In the event of treatment in a EU Member State, can I receive treatment in the establishment of my choice, or are there restrictions?

In the context of the 883/2004 Regulation, treatment is only covered at the establishment mentioned on the S2. The transfer request necessarily refers to a specific treatment at a specific establishment and is authorised by the CNS based on a favourable opinion from the CMSS.

If the request concerns a non-approved private establishment that does not accept the S2, the 2011/24 directive applies. Here again, if authorisation is granted, the entitlement to cover only applies to the specific establishment mentioned on the request.

How does cover work for the costs incurred through authorised treatment at a foreign hospital? Do I have to pay the foreign clinic directly?
  1. If you have S2 authorisation, the cost of treatment is covered by a health insurer in the country of treatment at the rates and tariffs of that country. Ideally, cover is provided through the third-party payment system, i.e. the fund in the treatment country covers the treatment and you are responsible only for the proportion payable by the patient and any supplements.

    If third-party payment does not apply, you must advance the costs and apply to your insurer in the treatment country or the Luxembourg fund for a reimbursement. The reimbursement is provided at the rates of the treatment country. On express request, an additional refund may be applied for from the competent fund in Luxembourg.
  2. In the case of a 2011/24 directive agreement, you must advance the costs in all cases and apply for reimbursement from the Luxembourg health fund. The reimbursement will be made at the rates, tariffs and conditions in force in Luxembourg.
What is covered?
  1. The S2 authorisation only allows for coverage under the same conditions and at the same rates and tariffs of the country of treatment. The S2 form does not guarantee full coverage of the medical costs incurred.

    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.) You can request an additional refund from the competent insurer. If the costs payable by you, excluding any supplements, are higher than the costs theoretically payable in your competent country, you can receive the difference within the limit of the reimbursement rates and tariffs in the competent country.

  2. With an authorisation under article 20 of the CSS (following transposition of directive 2011/24 into Luxembourg Law), healthcare is covered at the rates and tariffs of the competent country.
What can I do if the S2 is not taken into consideration by the provider and I receive an invoice to pay the total amount?

It is important to obtain as much information as possible about the coverage through the S2 form before treatment begins. The healthcare professional or even the health insurance fund in the country of treatment can provide you with information.

If the provider refuses coverage based on the S2, you 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. They may sometimes request a coverage form/certificate issued by this local health insurer. This is why it is important to seek information beforehand.

In the case of inpatient treatment, if you receive an invoice from the establishment even though you provided the S2 form, it is advisable to contact the establishment and try to arrange direct coverage. The CNS International Department can also assist; they will try to convince the provider to accept the S2 form and withdraw the invoice.

I would like to receive treatment in a country outside the European Union, Switzerland and the EEA. What rules do I need to observe?

Countries bound by bilateral agreement with Luxembourg should be distinguished from countries with no agreements.

All medical treatment planned before departure is subject to prior authorisation from the CNS based on a favourable opinion from the CMSS. The same procedure for requesting authorisation applies here and in the other EU and EEA countries as well as Switzerland.

  1. For countries linked to Luxembourg by an agreement in terms of social security, the principles laid out by the respective agreement apply. If authorisation is granted, some agreements provide for a specific form allowing for coverage according to the rates and tariffs in force in the country of treatment. The specific details of each agreement must be checked on a case-by-case basis.
    The countries are:
  2. Bosnia-Herzegovina LU-BiH112
    Macedonia L-RM112
    Montenegro MNE/L-112
    Serbia SRB/LUX 112
    Turkey TR/L-3
  3. For third-countries not linked to Luxembourg by an agreement in terms of social security, if authorisation is granted, you receive a certificate of coverage (titre de prise en charge) from the CNS. You must pay the costs of the treatment in full and apply for reimbursement on their return. The CMSS sets the refund amount or decides whether any increase may be granted
What reasons might lead to authorisation for treatment abroad being refused?

Administrative reasons

  • No affiliation;
  • Non-compliance with the APCM (prior authorisation from the CMSS);
  • Non-compliance with the authorisation request procedure;
  • The treatment falls outside the scope of health insurance;
  • The treatment is not covered or the conditions for coverage are not fulfilled;
  • ...

Medical reasons

  • The healthcare can be provided in Luxembourg within a time limit that is medically justifiable, taking into account his current state of health and the probable course of the condition;
  • A clinical examination shows with sufficient certainty that the patient will be exposed to a safety risk that cannot be considered acceptable given the potential advantage for the patient of seeking healthcare abroad;
  • There are valid reasons to think that the general public will be exposed to a considerable safety risk if the patient seeks healthcare abroad;
  • The healthcare must be provided by a foreign healthcare provider that arouses serious specific concerns with regard to compliance with standards and approaches relating to the quality of care and patient safety.
  • ...
What can be done if authorisation for treatment abroad is refused (appeal process)?

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.

Where can the S2 authorisation form be found?

The S2 authorisation form can be found under the section Forms.

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