Social Security


The following information on social security concerns current and future Associated Members of the Personnel (MPAs), in particular Users, Cooperation Associates (COAS) and Visiting Scientists (VISCs), whose contracts are handled by the Users Office.

MPAs employed in an EU or EFTA Member State

The European Union has defined a set of regulations (EU regulation 883/2004) on the coordination of social security systems in the EU and EFTA Member States (Iceland, Liechtenstein, Norway and Switzerland), which was put in force in 2010.

The EU regulation defines rights and rules for posted workers, who are employees in an EU or EFTA Member State and sent by their employers to carry out a service in another EU or EFTA Member State on a temporary basis.

The EU regulation requires posted workers to carry an A1 certificate with them at all times. This document certifies the social security situation of the employee.

According to the EU regulation, after postings longer than 24 months, posted workers can either:

  • switch to the social security system of the host country OR
  • apply for an extension and remain covered in the home country

The Swiss Authorities clarified that, despite the immunities and privileges of Associated Members of the Personnel (MPAs), the EU regulation 883/2004 also applies to MPAs (USER, COAS, VISC in particular), who are employed in an EU or EFTA Member State and are sent by their home institution to CERN.

As MPAs are not part of the CERN social security coverage, they have to comply with the national social security laws that are applicable to them. In particular, they have to carry an A1 certificate with them at all times when travelling to and while at CERN.

The A1 certificate should be requested by the employee (the MPA) from the employer (the home institution).

Situation in Switzerland (all MPAs)

The Swiss Authorities also clarified that Associated Members of the Personnel (MPAs) with an average presence at CERN of 55% or more as well as their family members who are resident in Switzerland and hold type “P” legitimation cards, are not subject to Swiss social insurance (AVS) and may not join the latter even on a voluntary basis.

As a consequence, MPAs who are posted workers in the sense of EU regulation 883/2004 and are posted to CERN for more than 24 months, need to apply for an extension to remain covered in the social security system in their home country, as they cannot join the Swiss system.

The Permanent Mission of Switzerland to the United Nations Office kindly provided an attestation (in French and English), that MPAs concerned can use as justification supporting their application for an extension to remain covered in the social security system of their home countries.

Situation in France (all MPAs)

An agreement on the social security of CERN Members of Personnel was concluded between France and CERN in 1970: Accord de sécurité sociale du 30 décembre 1970.

Article 1.1 of the agreement states that:

Les membres du personnel du CERN tels qu'ils sont définis par le statut du personnel de l'Organisation, exerçant tout ou partie de leur activité en territoire français, ne sont pas soumis aux législations françaises relatives à la sécurité sociale et aux prestations familiales.

(CERN Members of Personnel as defined by the Staff Regulations of the Organization, carrying out all or part of their activity on French territory, are not subject to French legislation relating to social security and family benefits.)

The agreement from 1970 is still in force and also includes MPAs, as confirmed by the CERN Legal Service.

Hence, Associated Members of the Personnel (MPAs) and their family members, who are resident in France (average presence at CERN of 55% or more) and are holders of a type “P” legitimation card, cannot get a French social security number and cannot join the French social security system, like for the Swiss social security system.

Exceptions are only possible for French citizens and for people (formerly) employed by French institutes.

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