You retired to the Dordogne, the Charente or a quiet street in Paris with a UK State Pension paid every four weeks from Newcastle, and now two tax authorities seem interested in the same money. HMRC continues to see a British pension, while the French tax office treats you as a French tax resident from the day you settled in France. Since Brexit, the Withdrawal Agreement protects your right to stay, but it does not change the tax answer: your UK State Pension, the flat-rate pension paid by the UK Department for Work and Pensions based on your National Insurance record, is in most cases taxable only in France once you live here, yet it must be declared correctly, and the question of French social charges depends entirely on which health cover you hold. Get the treaty article wrong and you pay in both countries; get the social charge test wrong and you either overpay several hundred euros a year or face a recovery notice with late interest. This guide explains, for a British reader with no French legal background, where the UK State Pension is taxed, how to declare it on the French return, when the contribution sociale généralisée (CSG, the general social contribution levied on replacement income), the contribution au remboursement de la dette sociale (CRDS, the contribution repaying the French social debt) and the contribution additionnelle de solidarité pour l’autonomie (CASA, the additional solidarity contribution for personal autonomy, levied on pensions) apply, what the portable document S1 (the European form showing you remain insured by the UK for health care while living in France) changes, and how to challenge double tax or a wrong social charge bill with the exact legal bases the administration itself uses.
I. Where is your UK State Pension taxed when you live in France and how do you declare it each year?
A. Is your UK State Pension taxable only in France under the France-United Kingdom double tax treaty?
The starting point is residence. Once you have your main home, your family life and your habitual presence in France, you become a French tax resident, and France taxes your worldwide income. The United Kingdom may still regard you as a UK resident under its own Statutory Residence Test in the year of departure, so the double tax treaty signed in London on 19 June 2008, published in France by official tax doctrine on the France-United Kingdom income tax convention of 19 June 2008, decides which country has the taxing right over each category of income. For private-sector pensions, including the UK State Pension earned through National Insurance contributions and any former private employment, the answer is in Article 18 of that convention, under which pensions and similar remuneration paid to a resident of one contracting state for past employment “ne sont imposables que dans cet Etat”, meaning they are taxable only in that state, subject only to the public-service exception in Article 19(2) In plain English, a pension paid for past employment to a person who lives in France is taxable only in France, subject only to the public-service exception.
That single sentence carries three practical consequences. First, if you live in France and receive a UK State Pension built up through private employment or self-employment, France alone taxes it, and the United Kingdom must give up its tax. The British guidance says the same thing in administrative language: You may not have to pay twice if the country you are resident in has a ‘double-taxation agreement’ with the UK, and the country notes for the France treaty explain that pensions for past private employment are taxable only in the residence state. Second, any UK income tax deducted at source through Pay As You Earn (PAYE, the British system where the pension payer deducts tax before payment) should stop once your non-resident status and treaty entitlement are recognised. In practice you complete HMRC Form P85 on departure, then claim relief under the treaty so that HMRC issues a no-tax (NT) code to your pension payer; until that code is in place, withholdings can continue and you reclaim them from HMRC, not from the French tax office. Third, the treaty exception for government service works the other way round. Article 19 of the same France-United Kingdom income tax convention provides that pensions paid by a contracting state for services rendered to that state, such as a British civil service, local authority, police or armed forces pension, remain taxable only in the paying state unless you are both a resident and a national of the other state without also holding the nationality of the paying state. A former National Health Service employee paid through a public body, a teacher paid by a local education authority, a soldier or a civil servant must therefore check Article 19 before assuming the Article 18 residence rule applies; many British retirees in France receive two pensions side by side, one under Article 18 taxable in France and one under Article 19 still taxable in the United Kingdom, and each must be entered on the correct line of the French return so that the elimination-of-double-taxation mechanism applies only where it should.
French domestic law then confirms that the pension enters the French tax base. Article 79 of the General Tax Code states: “Les traitements, indemnités, émoluments, salaires, pensions et rentes viagères concourent à la formation du revenu global servant de base à l’impôt sur le revenu.” Pensions therefore form part of your overall net income, called revenu global, in the same way as wages. The treaty does not exempt the pension from declaration; it allocates the taxing right to France, and French law then computes the tax. The Conseil d’Etat regularly recalls this architecture when it applies bilateral conventions to pensions and salaries, for example in its decision CE, 9th-10th chambers combined, 12 February 2020, No 435907, which interprets a tax treaty to decide which state may tax employment-linked income. The lesson for a British pensioner is simple: declare everything in France, then let the treaty article attached to each pension decide whether France taxes it, whether the United Kingdom taxes it with a French tax credit, or whether only the United Kingdom taxes it.
A common error is to leave the UK State Pension off the French return because it was “already taxed in England” or because it is paid net of UK tax into a British bank account. Both reasons are wrong. Until HMRC has issued the NT code, the pension arrives with UK tax deducted, but that deduction is provisional and treaty relief is claimed in Britain; France still requires the gross annual amount, converted into euros at the average annual rate published by the tax administration or the European Central Bank rate you consistently apply, to be entered on the return. Keeping your British account open does not change residence, and the obligation to declare foreign accounts on Form 3916 (the French form for declaring bank accounts opened abroad) sits alongside the obligation to declare the pension itself. Readers who arrived recently should read our detailed walkthrough of the first French return alongside this article: Just Moved to France from the UK After Brexit: Your First French Tax Return, which explains Forms 2042, 2047 and 3916 line by line. The State Pension explanation below assumes that first-return logic is already understood and focuses on the pension lines themselves.
B. How do you enter the UK State Pension on Forms 2042 and 2047 and how is the French tax actually calculated?
Take a concrete household: Susan, aged 68, moved to the Lot in March 2024 with a Withdrawal Agreement residence card, receives a UK State Pension of 11,500 pounds a year and a small former-employer pension of 4,000 pounds, and has no French-source income. Her husband, aged 70, receives a larger State Pension. Both are French tax residents for 2024. Each pension is converted into euros, added together, and then reduced by the French 10 per cent pension allowance before the progressive scale applies. Article 158, 5, a of the General Tax Code provides: “Les pensions et retraites font l’objet d’un abattement de 10 % qui ne peut excéder 4 439 €.” The allowance is calculated per pensioner in the household, with a minimum of 454 euros, and the ceiling quoted here is the figure in force in the version of the article applicable at the date of writing; it is indexed each year alongside the top of the first income tax band, so you must check the current Finance Act figure on your return. The allowance applies to the total of pensions and retirement annuities (rentes viagères, lifetime annuities) received by each member of the tax household (foyer fiscal, the household unit taxed jointly in France).
On paper, the declaration follows three steps. First, on Form 2047 (the supplementary return for foreign income), you enter each British pension in the pensions section, identifying the United Kingdom as the source country and the treaty as the France-United Kingdom convention of 19 June 2008. The 2047 then flows automatically into the main Form 2042 (the principal income tax return) when you file online; if you file on paper, you copy the totals into the pensions boxes on the 2042. British government-service pensions that remain taxable in the United Kingdom under Article 19 are still entered, but they open the right to a tax credit equal to the French tax on that income, so that France eliminates the double taxation without refunding more than its own tax. Second, the tax office applies the 10 per cent allowance, adds the net pensions to any other worldwide income, applies the family quotient (quotient familial, the system dividing taxable income into shares according to household composition), the progressive scale, then the décote (the automatic reduction for modest tax bills) and any reductions. Third, the office deducts withholding already operated through the French advance payment system only where French withholding existed; UK PAYE deducted without treaty relief is not credited by France, which is why sorting out the HMRC NT code early matters so much.
Three further points need attention because they generate most disputes. The exchange rate must be consistent: use one published annual average for all pensions in the same year and keep the calculation, because the tax office can ask how a sterling pension became a euro figure. The timing rule is payment-based: pensions are taxable in the year you actually receive them, including any arrears or back payments, not the year they relate to, unless a special spreading system (système du quotient, the averaging mechanism for exceptional income) applies to a large lump-sum arrears payment. And the year of arrival needs apportionment: if you moved mid-year and were resident in the United Kingdom for part of the year under the UK Statutory Residence Test and in France for the rest, each country taxes the slice that corresponds to its residence period under its own rules, with the treaty tie-breaker deciding any overlap. Keep the P85, the HMRC residency determination, your travel records, the NT code notice and every pension statement (P60, the British end-of-year pension statement, and monthly payslips); the French inspector cannot check HMRC systems directly and will ask you for these documents.
If HMRC refuses treaty relief or continues to deduct UK tax after you have established French residence, the remedy sits in the United Kingdom first: a formal claim under the double taxation arrangement, review by HMRC, then appeal to the First-tier Tribunal (Tax Chamber). In France, if the French office taxes a government-service pension that Article 19 reserves to the United Kingdom, or refuses the tax credit for income that remains taxable in Britain, the remedy is a réclamation contentieuse (the formal tax complaint to the French tax office) within the statutory deadline shown on your avis d’imposition (the French tax assessment notice), followed by appeal to the tribunal administratif (the French administrative court for tax disputes) in whose area you live, including the tribunal administratif de Paris for residents of the capital and the tribunaux administratifs of Versailles, Cergy-Pontoise and Melun for residents of the inner and outer Paris region. Paris-area readers should note the practical geography: the tax offices (services des impôts des particuliers) handling the 16th or 7th arrondissements apply the same national treaty, but hearings sit at the Paris court on rue de Lyon, with its own time limits and electronic filing practice. Always attach the treaty, the HMRC documents showing UK tax levied, and the French assessment showing the same income taxed again; a double-tax complaint without both assessments is routinely rejected as unproven.
II. Do you pay CSG, CRDS and CASA on your UK State Pension and how do you challenge a wrong social charge bill?
A. When are CSG, CRDS and CASA due on a British State Pension and when does an S1 exempt you?
Income tax is only half the bill. French pensions also bear social charges, and British pensions received in France can bear them too, but only if two cumulative conditions are met. The official tax doctrine summarises the test for foreign-source retirement pensions in BOI-RES-RSA-000219 of 11 August 2025 on liability to social contributions for foreign-source retirement pensions: liability depends on fiscal domicile in France and on being covered by a compulsory French health insurance scheme. The statute behind that summary is Article L. 136-1 of the Social Security Code, which states: “Il est institué une contribution sociale sur les revenus d’activité et sur les revenus de remplacement à laquelle sont assujettis : 1° Les personnes physiques qui sont à la fois considérées comme domiciliées en France pour l’établissement de l’impôt sur le revenu et à la charge, à quelque titre que ce soit, d’un régime obligatoire français d’assurance maladie”. The same pensions are also liable to the CRDS under the 1996 ordinance on social debt repayment and to the CASA under Article L. 137-41 of the Social Security Code, as the same official commentary recalls. The doctrine adds two points that British pensioners often miss: the charges apply whether the pensions come from a French or a foreign source and whether they are paid as an annuity or as a lump sum, and recovery on foreign-source pensions is made by assessment notice (“par voie de rôle”) issued by the tax office rather than by deduction at source by the pension payer.
The decisive question is therefore not where the pension comes from but which health cover you hold. French health cover for a person without French employment comes through two very different routes. The first is the protection universelle maladie, universally called PUMA (the French universal health protection giving residence-based cover to anyone living in France in a stable and regular way). Article L. 160-1 of the Social Security Code states: “Toute personne travaillant ou, lorsqu’elle n’exerce pas d’activité professionnelle, résidant en France de manière stable et régulière bénéficie, en cas de maladie ou de maternité, de la prise en charge de ses frais de santé”. If you joined the French system through PUMA, usually via your local caisse primaire d’assurance maladie, universally called CPAM (the local health insurance fund that manages affiliation, reimbursements and the carte Vitale, the French health insurance card), you are covered by a compulsory French scheme and the double test is met: French tax resident plus French scheme equals CSG, CRDS and, above the relevant threshold, CASA on the UK State Pension. The second route is the S1. The S1 portable document described by the Cleiss (the French centre for European and international social security liaison) allows a British State Pensioner insured in the United Kingdom to register for French health care while remaining insured by the United Kingdom, with the United Kingdom reimbursing France for the cost. Registration is made through the CPAM of your place of residence, as explained for newly arrived foreign nationals on service-public.fr: Health insurance for a foreign national settling in France. An S1 holder is not covered by a French compulsory scheme for the CSG test; the holder remains covered by the British scheme, so the second leg of the test fails and no CSG or CRDS is due on the British pension. That is the single most valuable document in this whole area: the same pension, the same amount, the same treaty article for income tax, but a completely different social charge bill depending on whether a valid S1 is registered.
The contribution base for pensions caught by the charges is set by Article L. 136-6 of the Social Security Code on the contribution on unearned income for capital income and by the replacement-income rules for pensions, applied after the same 10 per cent allowance logic adapted to social charges, with rates that depend on your revenus fiscal de référence (the reference tax income shown on your French assessment) and your household composition. Reduced rates, partial exemption and full exemption thresholds are updated almost every year in the Social Security Financing Act, so never copy a rate from a blog without checking the current scale on the return notice. Pensioners affiliated through PUMA with modest income often pay a reduced CSG rate or nothing at all, while pensioners above the thresholds pay the full rate plus CRDS at 0.5 per cent and CASA at 0.3 per cent on the pension. By contrast, a pensioner correctly registered with an S1 should see none of these three lines on the assessment for the British pension. Where both spouses receive pensions but only one holds an S1, perhaps because one reached State Pension age earlier, the exemption is personal: each pension is tested against its own recipient’s cover, and the assessment must be read line by line rather than assumed correct for the household.
A separate levy sometimes confused with these charges is the cotisation subsidiaire maladie, universally called CSM (the subsidiary health contribution due from PUMA members with little or no employment income but significant capital income). Article L. 380-2 of the Social Security Code makes PUMA members liable to an annual contribution only where employment income in France is below a threshold set by decree and where they received no retirement pension, annuity or unemployment benefit during the year. A British State Pensioner therefore falls outside the CSM by definition once the British pension is in payment, because the second condition fails; if a CSM is billed to a pensioner, the pension has not been properly recorded in the health file or the wrong affiliation code was used, and the file must be corrected rather than the contribution paid without question. Keep the S1 certificate, the CPAM attestation de droits (the certificate of health cover rights), every pension statement and every assessment notice together: the whole dispute turns on proving, for each year, where you lived and which scheme covered you.
B. How do you register the S1, correct the return and challenge double tax or wrong CSG in Paris and elsewhere?
Start with prevention, because correction takes months. Before your first French return, obtain the S1 from the UK International Healthcare Services (formerly the Overseas Healthcare Team) once your State Pension is in payment, then register it at the CPAM of your département before you file. In Paris that means the CPAM de Paris, with its own reception points by arrondissement; in the inner Paris region it means the CPAM of Hauts-de-Seine, Seine-Saint-Denis or Val-de-Marne according to your address. Bring your passport, Withdrawal Agreement residence card, proof of address, birth certificate with certified translation if requested, and the original S1. The CPAM issues the attestation de droits and orders the carte Vitale; check that your status reads as insured through the United Kingdom rather than as a PUMA member, because that code determines the social charge treatment downstream. Only then file the tax return, ticking the boxes that correspond to your cover and attaching no S1 to the tax return itself, since the tax office verifies cover through the social security files, not through paper attached to the 2042. If the S1 arrives after you filed, file a corrective return (déclaration rectificative, the corrected return filed online through your personal account on impots.gouv.fr) as soon as the attestation is issued, and keep proof of the S1 start date: exemption follows the period of British cover, not the date the plastic card arrived.
When the assessment arrives, read it in full. The avis d’imposition shows income tax on one side and prélèvements sociaux (the social levies collected by the tax office) on the other. For each British pension, verify the gross euro amount, the allowance, the treaty treatment, and then the three social lines. If CSG, CRDS or CASA appear on a pension covered by a valid S1 for the whole year, the error is a cover-code error and the remedy is a tax complaint. File a réclamation through your online account or by recorded letter to the service des impôts des particuliers shown on the notice, within the deadline printed on the notice, asking for discharge (dégrèvement, the cancellation of tax wrongly assessed) of the social charges on the British pension, and attach the S1 certificate, the CPAM attestation covering the year, the pension statements and the assessment. Ask expressly for suspension of enforced recovery while the complaint is examined where the sums are significant. If the office maintains the charge, appeal to the tribunal administratif of your residence: Paris for the capital, Versailles, Cergy-Pontoise or Melun for much of the Paris region, and the tribunal of your département elsewhere. The courts apply the double test strictly, and the case law on affiliation is now settled.
The courts have repeatedly held that only one social security legislation can apply at a time. In two 2025 decisions on levies and affiliation, the Second Civil Chamber of the Court of Cassation recalled the principle in almost identical terms: Cass. 2nd civ., 25 September 2025, No 22-24.634 and Cass. 2nd civ., 25 September 2025, No 22-20.036. The first recalls that European coordination rules “consacrent le principe d’unicité de la législation de sécurité sociale, selon lequel la personne à laquelle les règlements s’appliquent n’est soumise qu’à la législation d’un seul État membre, en sorte que celle-ci, affiliée à un régime de sécurité sociale d’un État membre, ne doit pas contribuer au régime de sécurité sociale d’un autre État membre (CJUE, arrêt du 26 février 2015, De Ruyter, C-623-13, point 35)”. The earlier ruling on contributions deducted by an employer, Cass. 2nd civ., 6 June 2024, No 21-23.396, applies the same affiliation logic to recovery by URSSAF (the French body collecting social contributions). For a British S1 holder, the reasoning transfers directly: a pensioner insured by the United Kingdom and registered in France through the S1 cannot simultaneously be treated as covered by the French compulsory scheme for the same period, so the CSG test fails. Quote the S1 dates precisely; a gap of even a few weeks between arrival, PUMA cover pending the S1, and S1 registration can justify a pro-rata charge for the uncovered weeks, and the administration will seize on any undocumented gap.
Where the dispute is about income tax rather than social charges, the evidence bundle is different but the method is the same. For a private pension taxed in both countries, attach both assessments, the HMRC employment history and pension statements, proof of French residence (lease or title deed, utility bills, residence card, travel records), and the treaty with Article 18 highlighted. For a government-service pension, attach proof of the employing body and the nature of the service, because Article 19 turns on who paid the pension and in what capacity, not on the label the pension payer uses. Where sterling moved sharply during the year, show the rate source and calculation; inspectors in Paris, Lyon or Bordeaux see British pensions every week and accept a consistent published average, but they reject unexplained round conversions. And where the pension includes arrears covering several years, ask expressly for the quotient system on the return itself; once the assessment is issued without it, the complaint must demonstrate that the arrears meet the statutory definition of exceptional income, which is harder than ticking the box correctly in the first place.
Time limits decide everything. Tax complaints, claims for treaty relief in the United Kingdom, S1 backdating requests and health-file corrections each run on their own clock, and missing one can leave the others without effect. File the French complaint within the period on the notice, pursue HMRC relief in parallel rather than waiting for the French outcome, and register the S1 as soon as entitlement arises rather than at the end of the first year. Keep every document for at least the French reprise period (the period during which the tax office can reassess, generally three years, longer where foreign income or accounts are involved) plus the current year. British retirees who manage this paper trail spend one careful afternoon a year on the return; those who discover the S1, the NT code and the treaty only after the first assessment spend a year in correspondence. The law favours the careful: exclusive French taxation under Article 18 protects the private pension from British tax, the S1 protects it from French social charges, and the courts enforce both where the proof is complete.
Conclusion
A British State Pension received while living in France sits at the meeting point of three systems: the France-United Kingdom treaty for income tax, French domestic law for the calculation, and European coordination rules for health cover and social charges. The treaty gives France the exclusive right to tax the private State Pension of a French resident, French law brings it into worldwide income with the 10 per cent allowance, and the S1 decides whether CSG, CRDS and CASA are added on top. Register the S1 before filing, secure the HMRC NT code so the same pension is not taxed in Britain, declare the gross sterling amount converted consistently into euros, and read the assessment line by line. Where the administration taxes twice or charges social levies on an S1-covered pension, the complaint, supported by both assessments, the S1 certificate and the CPAM attestation, restores the treaty and the correct affiliation. Handled in that order, the British State Pension becomes what it should be in France: one declaration, one tax, and no social charge where the United Kingdom remains the competent state for health care.