You retired to France with a British State Pension, and the first French tax notice raises three urgent questions: does France really have the right to tax a pension paid by the United Kingdom, how do you declare it without being taxed twice, and why does the notice add social charges — contribution sociale généralisée (CSG, the broad social contribution) and contribution au remboursement de la dette sociale (CRDS, the debt-repayment contribution) — to a pension that never passed through the French social security system? Since Brexit, these questions trap thousands of British residents every spring, and mistakes are expensive: a pension declared in the wrong box, a credit for foreign tax forgotten, or CSG paid by someone holding a valid S1 healthcare certificate can cost hundreds of euros a year, every year. This guide answers each question in order. It explains the exact treaty rule that gives France — and not the United Kingdom — the right to tax your State Pension, the precise declaration path on the French foreign-income forms, the narrow but valuable cases where you owe no CSG or CRDS at all, and the procedures and deadlines for challenging a double charge or an unlawful levy. Every decisive proposition rests on a verifiable official text, quoted word for word and linked below.

I. Where is your British State Pension taxed when you live in France and how do you declare it?

A. Is my UK State Pension taxable only in France under Article 18 of the treaty?

The starting point is your French tax residence. Under Article 4 B of the French Tax Code (Code général des impôts), “Sont considérées comme ayant leur domicile fiscal en France au sens de l’article 4 A : a. Les personnes qui ont en France leur foyer ou le lieu de leur séjour principal”. In plain English: if your home (foyer, your family and settled home) or your main place of stay is in France, France treats you as tax-resident. Most British retirees who live year-round in the Dordogne, Brittany or Paris meet this test without difficulty, even when they keep a British bank account, receive a pension paid from Newcastle, or visit children in the United Kingdom for several weeks a year. Once you are French tax-resident, Article 79 of the Tax Code provides that “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.” Your British State Pension therefore falls, in principle, inside the French income-tax base.

The second step is the double tax treaty signed in London on 19 June 2008, in force since 18 December 2009. Its pensions rule is short and decisive. Article 18 of the 2008 United Kingdom–France double taxation convention reserves the exclusive right to tax pensions paid for past employment to the state where the pensioner is resident. The British State Pension — the new State Pension for men born on or after 6 April 1951 and women born on or after 6 April 1953, and the basic plus additional State Pension for those who reached pension age earlier — is paid in consideration of past National Insurance contributions, which is past employment-related contributions in treaty terms. It is not a government-service pension. So if you are resident in France within the meaning of the treaty, Article 18 gives the exclusive right to tax to France, and the United Kingdom should not tax it. In practice, HM Revenue and Customs puts this into effect through a nil-tax code once you have claimed residence treatment, usually with the France-Individual claim form; the pension then arrives gross in the United Kingdom and is taxed only in France.

One common confusion must be cleared up immediately, because it costs readers money. Article 19 of the same convention, on government service, provides a mirror rule for public-sector pensions: pensions paid by a state or local authority for services rendered to it are taxable only in that paying state. A civil service pension, a teacher’s pension paid out of a local-authority fund, an NHS pension, a police or armed-forces pension, or a Foreign Office pension falls under this paragraph and stays taxable in the United Kingdom even when you live in France. The State Pension does not. Readers who receive both — a State Pension plus, say, a teacher’s pension — must therefore split their pensions into two baskets: the State Pension declared and taxed in France under Article 18, and the government-service pension declared in France but relieved from French tax by a credit equal to the French tax, because the United Kingdom keeps the exclusive right under Article 19. France still asks you to report worldwide income, then neutralises the French tax on the Article 19 pension through the treaty credit mechanism; it never simply ignores it. Our detailed analysis of that second basket, including the treatment of the 25 per cent lump sum paid without United Kingdom tax and of Crown pensions, is set out in our guide to British pensions, lump sums and Crown pensions in France.

France then taxes the State Pension through its ordinary machinery for pensions. Article 158-5-a of the Tax Code provides that “Les pensions et retraites font l’objet d’un abattement de 10 % qui ne peut excéder 4 439 €.” In ordinary language: pensions and retirement income benefit from a 10 per cent allowance, capped at 4,439 euros per tax household (the figure in the version of the article in force on 9 October 2026; the cap is revised each year with the top of the first income-tax band, so always check the current finance act figure before filing). The allowance applies automatically to the total pensions of the household; each pensioner member also benefits from the minimum allowance floor stated in the same article. The balance is added to your other worldwide income and taxed at the progressive scale (barème, the graduated rate table). Nothing in this mechanism depends on the pension being French: once Article 18 allocates the taxing right to France, your Newcastle-paid pension is taxed exactly like a French pension of the same amount.

B. How do I declare my UK State Pension on the French foreign-income forms without being taxed twice?

French residents declare worldwide income each spring, and foreign pensions follow a two-form path that must be respected precisely. The pension is first detailed on form 2047, the foreign-income return (déclaration des revenus encaissés à l’étranger), available on the impots.gouv.fr page for formulaire n°2047, and the totals are then carried onto the main return 2042. The administration’s own guidance on how income received from abroad is taxed confirms the principle that treaty rules determine which country taxes what, while the declaration obligation in France remains for residents. Concretely, for a State Pension falling under Article 18: enter the gross annual amount in sterling converted into euros at the rate applicable for the year, in the pensions section of form 2047, identifying the United Kingdom as the source country; report any United Kingdom tax that was exceptionally withheld, so the French return shows it; then carry the net figure to the pensions box of form 2042. If no United Kingdom tax was withheld — the normal outcome once your nil-tax code is in place — the French return simply taxes the pension in full at the scale, after the 10 per cent allowance described above.

Three practical errors generate most double-tax bills. The first is declaring the pension only in the United Kingdom through self-assessment while filing a French return that omits it: France then issues an automatic correction (proposition de rectification, the formal proposal to reassess) with penalties when the exchange of information reveals the omission, because residence makes the pension declarable in France. The second is declaring the gross pension in France but forgetting to claim the treaty treatment for a government-service pension received alongside it, so the Article 19 pension is taxed in both countries without the credit that neutralises the French charge. The third, specific to the transition year, is the arrival or departure year: someone who moves to France in June becomes French tax-resident from the move, and only the pension instalments from residence onwards belong in the French base, with the earlier instalments remaining United Kingdom-taxable; splitting the year wrongly in either direction produces a bill from one administration or the other. Keep every document that proves the calendar: the leaving-the-United-Kingdom date, the French lease or completion deed (acte authentique, the notarial deed of purchase), the residence permit or Withdrawal Agreement card, and the HMRC coding notice showing the nil-tax treatment.

Exchange-rate and timing discipline matters as well. Convert each monthly instalment at a consistent, defensible rate — the European Central Bank reference rate or your bank’s applied rate — and keep the schedule, because the tax office (service des impôts des particuliers, the local personal-tax office, known as the SIP) can ask for it during a documentary check (contrôle sur pièces, a desk audit conducted by correspondence). In Paris and the inner suburbs, your file belongs to the SIP of your arrondissement or commune of residence; the contact details appear on your first avis d’impôt (the assessment notice). Declare the pension even when it is modest: the State Pension alone rarely triggers a large bill after the allowance and the household quotient (quotient familial, the system that divides household income into shares for the rate calculation), but an undeclared pension triggers interest and penalties that a declared one never does. And if United Kingdom tax was wrongly withheld despite Article 18 — typically because the nil-tax code arrived late — do not deduct it yourself from the French base; claim repayment from HMRC for the United Kingdom side and pay the French tax in full, because the treaty gives France the whole base and the United Kingdom side is corrected by refund, not by a French deduction.

II. Do you owe CSG and CRDS on your British State Pension and how do you challenge an unlawful bill?

A. Do I pay social charges on my State Pension, or does my S1 certificate exempt me?

Income tax is only half the bill. France adds social levies (prélèvements sociaux, the family of social contributions collected on income) to most residents’ income, and pensions are no exception in principle. The founding rule is Article L. 136-1 of the Social Security Code (Code de la sécurité sociale): “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”. Read carefully, because the exemption hides in the second half of that sentence: you owe CSG on replacement income such as pensions only if you are simultaneously French tax-resident and covered by a compulsory French health-insurance scheme (à la charge d’un régime obligatoire français d’assurance maladie). A British retiree who is French tax-resident but whose healthcare is carried by the United Kingdom under an S1 certificate — registered with the local health fund (caisse primaire d’assurance maladie, known as the CPAM) precisely as a person not affiliated in France for cost purposes — fails that second condition and therefore falls outside CSG on replacement income. The pension remains fully liable to income tax; only the social charges drop away.

The rates show why this distinction is worth real money. Article L. 136-8 of the Social Security Code provides that “Sont assujetties à la contribution au taux de 8,3 % les pensions de retraite, et les pensions d’invalidité.” An 8.3 per cent CSG on the pension, plus the CRDS levied alongside it and the solidarity contribution for autonomy (contribution additionnelle de solidarité pour l’autonomie, known as CASA) on pensions liable to CSG, together represent roughly a tenth of the pension taken as social levies. The administration’s own English-language guidance on CSG and CRDS on employment and replacement income describes the scope and the reduced-rate and exemption bands tied to the household’s reference income (revenu fiscal de référence, the reference tax income shown on the assessment notice): below the lowest threshold, pensions escape CSG entirely; in the middle band they bear a reduced rate; above it they bear the full rate. Two cumulative filters therefore decide your position: first, are you affiliated to a French compulsory scheme at all; second, if yes, where does your reference income sit against the annual thresholds. S1 holders stop at the first filter and owe nothing; PUMA affiliates (protection universelle maladie, the universal residence-based health cover) continue to the second.

Three profiles cover nearly every British reader. The first is the S1 holder: you receive a United Kingdom State Pension, you obtained the S1 form from the United Kingdom, you registered it with your CPAM — in Paris, the CPAM de Paris — and your French carte Vitale (the green health-insurance smart card) shows the cross-border funding. Your State Pension, and any private pension paid alongside it, should bear no CSG, no CRDS and no CASA, because you are not à la charge of the French scheme. If your assessment shows these levies, the levy is challengeable as a matter of affiliation, not of income level. The second profile is the early retiree with no S1: not yet drawing a State Pension, living in France under PUMA after three months of stable residence — Article L. 160-1 of the Social Security Code provides that “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 dans les conditions fixées au présent livre” — and therefore affiliated to the French scheme: any pension already drawn, such as a spouse’s pension or an early occupational pension, bears the levies at the rate matching the household’s reference income. The third profile is the household where one spouse holds an S1 and the other does not: the levies are personal, so the S1-covered spouse’s pensions escape while the PUMA-affiliated spouse’s pensions bear them, and a single joint assessment that charges both spouses identically deserves a line-by-line check.

The courts confirm that affiliation, not nationality or the flag on the pension, decides these disputes. In a judgment published in the Bulletin on 25 September 2025, the Second Civil Chamber of the Court of Cassation, appeal no. 22-24.634, rejected a frontier worker’s claim for repayment of French health contributions, holding on the facts that her affiliation to the French scheme justified the levy and that no reasonable doubt of European Union law required a reference to Luxembourg. The lesson cuts both ways and favours well-documented S1 holders: where French affiliation is established, the levy stands; where the pensioner proves coverage by another scheme through a registered S1, the legal basis for CSG on replacement income collapses under Article L. 136-1 itself. Similarly, on 9 April 2026, the Nancy Administrative Court of Appeal, judgment no. 24NC02280, examined claims for discharge of CSG, CRDS and CASA assessed on retirement pensions received as capital, and made the outcome turn on the claimants’ residence position and on whether their pension amounts exceeded the thresholds of Article L. 136-8 for the reference year. The practical message for British readers is identical in both courts: levy disputes are won with affiliation certificates and reference-year figures, never with general arguments about fairness or Brexit.

B. My assessment charges CSG or double tax: how do I challenge it before the deadline expires?

Act in the order the law rewards: correct the affiliation record first, then file the tax challenge inside the limitation period. If CSG, CRDS or CASA appears on an S1-covered pension, start with the CPAM and the tax office simultaneously. Ask the CPAM for a written statement of your affiliation position for the year concerned, confirming registration of the S1 and the absence of affiliation to the French compulsory scheme for cost purposes; parallel cases show that assessments are frequently corrected once that certificate reaches the file. At the same time, file the formal administrative complaint (réclamation contentieuse, the written claim to the tax administration that opens any dispute) with the SIP that issued the assessment, attaching the S1, the CPAM registration, the assessment notice, and a computation showing the levies charged on the pension lines. Raise the Article L. 136-1 affiliation argument explicitly: you were domiciled in France for income tax but not covered by a compulsory French health scheme, so the CSG on replacement income had no legal basis. Keep proof of filing and the date, because the administration’s silence for six months counts as an implied rejection (rejet implicite, the deemed refusal that opens the door to the court) and starts the next clock.

For double-tax charges — France taxing a government-service pension that belongs exclusively to the United Kingdom under Article 19, or France refusing the treaty credit — the complaint invokes the treaty directly alongside domestic law. Identify the pension line by line, state the treaty article for each (Article 18 for the State Pension, Article 19 paragraph 2 for the government-service pension), attach the HMRC coding notice or P60 showing United Kingdom taxation of the Article 19 pension, and compute the credit France should have granted. Where both administrations claim the same income and the complaint fails, the treaty provides a mutual-agreement procedure (procédure amiable, the state-to-state negotiation between the two tax authorities to eliminate double taxation) under its Article 26, requested through the competent authority of either state; this route runs alongside, not instead of, domestic deadlines, so never let a domestic time limit expire while waiting for the negotiation. And where the administration answers that your government-service pension is really a private pension — a frequent dispute for outsourced public-sector employments and for teachers in private establishments — demand the precise legal characterisation in writing: the treaty test turns on who pays the pension and out of which funds, not on the job title you once held.

Deadlines decide everything, so calendar them the day the assessment arrives. The standard complaint must reach the administration by 31 December of the second year following the year the assessment was issued: for an income-tax notice issued in 2026 on 2025 income, that means 31 December 2028. If the administration rejects expressly or stays silent for six months, you have two further months to bring the case before the administrative court (tribunal administratif, the first-instance court for tax disputes) — in Paris, the Tribunal administratif de Paris for residents of the capital, with appeal to the Cour administrative d’appel de Paris. Attachments win these cases: the treaty text, the S1 with CPAM registration stamp, the P60 and coding notice, the 2047/2042 copies as filed, the exchange-rate schedule, and the computation of the disputed levies line by line. Ask in the alternative (à titre subsidiaire, the fallback request courts expect): primarily discharge of the unlawful levy, alternatively reduction to the correct reduced rate under the reference-income bands. Courts grant the fallback more readily than an all-or-nothing claim, and the administration settles well-documented affiliation files before the hearing more often than practitioners admit.

Conclusion

Your British State Pension, once you are French tax-resident, belongs to France under Article 18 of the 2008 treaty: declare it on forms 2047 and 2042, let the 10 per cent pensions allowance apply, and pay French income tax on the balance while the United Kingdom stands back. Keep government-service pensions in their separate Article 19 basket so France grants the credit instead of a second charge. Then check the social levies with equal care: 8.3 per cent CSG on retirement pensions assumes French health affiliation, and a registered S1 removes that assumption — and the levy with it. Where the assessment gets any of this wrong, the registered S1, the treaty articles and the timely complaint correct it. File the affiliation proof first, the treaty computation second, and the court application last, always inside the deadlines, and the system that first looked like double taxation becomes what the treaty promised: one pension, taxed once, in the right country.