1. Who needs to complete an income declaration?

All members of the personnel, regardless of the category to which they belong (employed or associated), who are considered to be resident in France must complete an income declaration. Members of the personnel must decide for themselves whether they are resident in France, referring to the criteria laid down by the French tax authorities, which notably consider individuals to reside in France if:

• they have their main home in France (in particular if their spouse/partner and/or children live with them); or
• they perform a professional activity, whether in receipt of a salary or not, in France, unless they can prove that the activity performed in France is ancillary (secondary); or
• their economic interests are centred in France.

However, the French tax authorities have the sole authority to assess individual circumstances. If in doubt, members of the personnel should contact the Service des impôts des particuliers (private citizens' tax office, SIP) of their place of residence.

2. When to complete your declaration

Declarations can be submitted online from 10.04.2025.

The deadlines for submitting declarations online are as follows:

• 22.05.2025 for departments 01 to 19,
• 28.05.2025 for departments 20 to 54,
• 05.06.2025 for departments 55 to 976.

The deadline for submitting declarations on paper is 20.05.2025, based on the postmark date (including for non-residents of France who are required to submit a declaration).

3. How to complete your declaration

3.1 Members of the personnel declaring their income in France for the first time (first-time declarants)

Members of the personnel who are submitting their first income declaration in France are not yet known to the French tax authorities. Their declaration relates to the income received since their arrival in France, during the reference year.

They must initiate the declaration process on their own initiative and, except in special circumstances, can only submit their declaration in paper form.

To do this, they must at least complete the following forms and send them (with supporting documents) to the SIP of their place of residence:

• form 2042 – “Déclaration de revenus” (“Income declaration”);
• form 3916-3916 bis to declare any bank accounts held outside France.

Blank declaration forms can be downloaded from the website www.impots.gouv.fr (enter the number of the form that you need to complete in the search bar) or obtained from a Direction Départementale des Finances Publiques (Departmental Directorate for Public Finances, DDFIP) office: Valserhône SIP or its local branch in Gex.

Declarants must enclose with the form the following supporting documents:

• a copy of their identity document (e.g. identity card, passport, family record book, etc.);
• a copy of the rental contract for their accommodation or other proof of domicile;
• a statement of their bank account details (relevé d'identité bancaire, RIB);
• their internal tax annual certificate and/or individual annual statement.

Once their first income declaration in paper form has been submitted (along with the necessary supporting documents), the person will be allocated a tax number (numéro d’identification fiscale, NIF). When they receive their tax assessment notice (see section 6 below), they will also be given all the access codes needed to create their espace particulier (personal account) online.

Special case: as the cost-of-living allowance (COLA) is taxable in France, members of the personnel in receipt of such an allowance can obtain a tax number as soon as they arrive in France, by completing form 2043 and returning it, along with the supporting documents, to the SIP of their place of residence (see question 1.8 of the FAQ prepared by the Valserhône SIP).

3.2 Members of the personnel with a French tax number

All declarations must be submitted online.

Members of the personnel who already have a French tax number (numéro d’identification fiscale, NIF) must have created an espace particulier (personal account) on the website https://www.impots.gouv.fr/accueil.

They are notified of the opening of the online income declaration service by an email sent to the address indicated in their espace particulier and can thus complete their income declaration as soon as the online service opens.

Only those who are unable, for technical or other reasons, to submit an online declaration may continue to submit a paper declaration. The paper forms needed to submit the income declaration will be sent to those concerned, in batches, between the middle and the end of April. Alternatively, these forms can be downloaded from the website of the Ministry of Economics and Finance (enter the numbers of the required forms in the search bar) or obtained from the SIP of the person’s place of residence.

4. Declaring income received from CERN

N.B.: People who have received an internal tax annual certificate and an annual individual statement for the same tax year must follow the procedures outlined in sections 4.1 and 4.2, respectively, to declare the corresponding income. See question 1.9 of the FAQ prepared by the Valserhône SIP.

4.1 Members of the personnel receiving an internal tax annual certificate

Each year, the Organization levies an internal tax (calculated on the basis of CERN’s own tax scale) on the financial and family benefits it pays to certain categories of members of the personnel. Those concerned receive an internal tax annual certificate from the CERN administration and are therefore exempt from national taxation on the financial and family benefits paid by CERN.

These members of the personnel must complete their declaration as follows:

1. Under the heading “Traitements, Salaires”, they must not indicate the amounts of the financial and family benefits paid by CERN, which are subject to internal taxation by the Organization.

2. They must tick box 8FV and box 8UU (if one or more bank accounts are held outside France). These boxes can be found in section 8 of the paper form, entitled “Divers”. In the online declaration, this section is accessed in step 3 "Revenus et charges" under the heading “Divers" by ticking the box "Comptes à l'étranger, revenus de source étrangère, reprise de réductions ou de crédit d'impôt".

3. They must tick “Informations – Mention expresse” at the end of the online declaration and add the comment “Membre du personnel du CERN assujetti à l'impôt interne du CERN et, à ce titre, exonéré d'impôt sur les prestations financières et familiales versées par le CERN” (“Member of the CERN personnel subject to internal CERN taxation and therefore exempt from taxation on the financial and family benefits paid by CERN”). In the paper form, the same words must be written on page 2, under the heading “Informations", or on a separate sheet if this section is already prefilled.

4. They must send the internal tax annual certificate:

• using the secure messaging system accessible from their espace particulier on the website www.impots.gouv.fr, or
• if this is not possible, by post to the SIP of their place of residence, together with the references of the online declaration, or
• together with the paper form.

Documents submitted by email will not be accepted.

Members of the personnel are invited to consult the FAQ prepared by the Valserhône SIP, which provides answers to the questions most frequently asked by members of the CERN personnel.

4.2 Members of the personnel receiving an individual annual statement

Members of the personnel who have received an individual annual statement from the CERN administration must complete their French tax declaration form as follows:

1. In box 1AF (“Traitements, salaires – salaires de source étrangère avec crédit d'impôt égal à l'impôt français”) and box 8TK (“Revenus de source étrangère ouvrant droit à un crédit d'impôt égal à l'impôt français”), they must state the amount of salary and other income that might be liable for taxation in their country of origin (this includes the cost-of-living allowance – COLA – if it is liable for taxation in the country of origin).

2. In box 1AG (“Autres salaires imposables de source étrangère”), they must state the amount of salary and other income that is not liable for taxation in the country of origin (this includes the COLA if it is not liable for taxation in the country of origin), deducting from these amounts any costs incurred as a result of membership of a compulsory health insurance scheme.

3. If the COLA is reported under 1AG (and is therefore liable for taxation in France), the actual professional expenses incurred as a result of living in the local area may be reported in box 1AK. These expenses will be deducted from the tax base if they are considered by the tax authorities to be justified and inherent to the individual’s professional activity in the local area as an associated member of the personnel sent to CERN by their employer to contribute to the Organization’s activities. The type of deduction is at the taxpayer’s discretion:

• either a flat rate (10%, applied automatically by the tax authorities);
• or based on proof of the actual expenses incurred. “Actual expenses" include the cost of transport between home and the workplace, additional food costs, union dues and professional liability insurance premiums, the cost of professional training courses and the cost of dual residence (rent, residence tax, water and electricity bills and any other expense justified by the presence of the members of the personnel in the local area, provided that they can justify their need to reside for professional reasons in a place other than their usual place of residence, where their spouse or registered partner lives). A detailed calculation of these costs must be submitted along with the declaration, either on a separate sheet of paper or in the space provided for this purpose in the online declaration. Members of the personnel should keep proof of these expenses for several years, as it may be requested by the tax authorities in the event of a tax compliance check.

d. They must send the individual annual statement:

• using the secure messaging system accessible from their espace particulier on the website www.impots.gouv.fr, or
• if this is not possible, by post to the SIP of their place of residence together with the references of the online declaration, or
• enclosed with the paper declaration.

Documents submitted by email will not be accepted.

Very important: members of the personnel who receive an annual individual statement must not tick box 8FV.

For help with specific problems, members of the personnel must contact the SIP of their place of residence.

4.3 Associated members of the personnel in receipt of neither financial and family benefits paid by CERN nor a cost-of-living allowance

Associated members of the personnel who receive neither financial or family benefits nor a COLA may nonetheless be liable for taxation in France on their other income (e.g. remuneration paid by their home organisations) and must therefore declare this income, even if it is liable for taxation in their home country.

Indeed, such income (e.g. remuneration paid by home organisations) is normally liable for taxation in the country of origin. In some cases, an agreement to avoid double taxation exists between France, as the country of residence, and the country of origin. This income is thus taxed either in France or in the country of origin. In all cases, associated members of the personnel must use form 2047 to declare income received abroad.

Please note that this is not the same as form 2047-SUISSE, which concerns cross-border workers and does not apply to members of the CERN personnel.

1. If they receive remuneration from an organisation that is not based in France and if this remuneration is already taxed in the other country, members of the personnel must add the following comment at the end of the online declaration, under the heading “Informations – Mention expresse”: “Membre du personnel du CERN (utilisateur/other associate status, as applicable), de nationalité [nationality], rémunéré par [name and address of the employing organisation], imposable en [country of taxation]”. In the case of paper declarations, this comment must be added on page 2, under the heading “Informations”, or on a separate sheet of paper if this section is already prefilled.

2. This income from a foreign source (outside France) must be entered in sections 1 and 6 of form 2047. In addition, if, and only if, the income is already taxed in the country of origin, the annual amount of net income, without deduction of the annual tax paid abroad, must be entered in boxes 1AF and 8TK on form 2042.

N.B. Associated members of the personnel are invited to consult the relevant agreement between the Government of the French Republic and their country of origin in order to avoid double taxation.

International agreements can be found on the website impôts.gouv.fr

Those concerned are invited to contact the SIP of their place of residence for help with any specific questions relating to their declaration obligations.

4.4 Other income

For any specific questions on how to complete the various sections of the declaration, taking into consideration any other income they may have and their specific circumstances, members of the personnel are invited to refer to the information sheet attached to the declaration (or available on the website of the Ministry of Economics and Finance – fiscal administration) or to contact the SIP of their place of residence. Useful information can also be found in the FAQ document prepared by the Valserhône SIP.

4.5 Bank accounts held abroad

Bank accounts held abroad (i.e. outside France), even if they are used solely to receive financial and family benefits or cost-of-living allowances, must be declared. The declaration must be done every year (see point 4 of the FAQ prepared by the Valserhône SIP).

Associated members of the personnel in receipt of other income should also refer to section 4.3.

5. Special cases

5.1 Swiss members of the personnel residing in France

Like all people residing in France, Swiss members of the personnel residing in France must complete their income declaration form in accordance with the instructions given above.
Those who have retained an economic link with Switzerland (e.g. they own property in Switzerland) must also complete the Swiss income declaration form and submit it in accordance with the instructions provided in the Income tax declaration in Switzerland procedure.

5.2 Nationals of the United States and holders of a US permanent resident (“green”) card

CERN is not in a position to give advice on these highly specific situations and invites the members of the personnel concerned to contact the SIP of their place of residence and/or the US consular authorities. They can also refer to point 3.7 in the FAQ prepared by the Valserhône SIP.

5.3 Former members of the personnel

• Retirees or other beneficiaries of CERN Pension Fund benefits

Benefits paid by the CERN Pension Fund are subject to the standard conditions of income tax. The procedures described herein therefore do not apply to that income (retirement pensions, disability pensions and other benefits).

• Former staff members receiving CERN unemployment insurance benefits

Unemployment insurance benefits paid to former CERN staff members are also subject to the standard conditions of income tax. The procedures described herein therefore do not apply to that income.

6. Income tax assessment notice

Members of the personnel who have opted to submit their income declaration online will receive an email, to the address indicated in their espace particulier, as soon as their income tax assessment notice is available. They can then consult, download and, if necessary, print it. Members of the personnel who have completed a declaration in paper form and reside in France will receive a document entitled “Avis d'impôt – Impôt sur les revenus” (“Tax assessment notice – income tax”) by post. They must not return this document to the SIP, but must keep it.

The tax assessment notice may be requested by French authorities seeking information on an individual’s tax situation in France.
Members of the personnel can obtain further information directly from the SIP of their place of residence.

7. Taxe d’habitation (residence tax) and taxe foncière (property tax) in France

The Organization is not competent to provide information on these categories of tax. Members of the personnel are invited to contact a tax adviser (fiduciary) or the relevant national tax authorities for further information on residence tax and property tax.

More details are available on the website www.impots.gouv.fr and in the FAQ prepared by the Valserhône SIP (see point 3.3).

Since 2023, households are no longer liable for residence tax on their primary residence, which is determined on the basis of the address given in their income declaration (address on 1 January of the tax year in question).

Residence tax continues to apply to secondary residences and to vacant properties (see this article in the CERN Bulletin). All owners of a primary residence, a secondary residence or rented accommodation located in France must submit an additional declaration to the tax authorities on the website www.impôts.gouv.fr. For further information, please refer to the webpage “Déclaration des biens immobiliers” (“Declaration of real estate”).