You are British, you live in France, and your healthcare is covered by an S1 form issued by the United Kingdom. Then your French tax notice arrives, and the social charges on your rental income, your interest or your capital gain read 17.2 per cent. For an S1 holder, that figure is very often wrong. Where France is not the state responsible for your sickness cover, you do not owe the CSG (contribution sociale généralisée, the general social contribution) or the CRDS (contribution pour le remboursement de la dette sociale, the social debt repayment contribution) on income from capital. Only the prélèvement de solidarité (the solidarity levy, a 7.5 per cent tax-like charge that is not a social security contribution) remains due. The French tax administration says so itself on impots.gouv.fr, and the Cour de cassation applies the single-legislation rule strictly. This guide explains which income is covered, how to prove your position with your S1, and how to claim back overpaid charges before the deadline expires.

I. Why a British S1 holder in France does not owe CSG-CRDS on capital income

A. What your S1 actually proves, and how the single-legislation rule protects you

An S1 (formerly E106, E109 and E121) is a portable document issued by the state that pays your pension or employs you, certifying that you are insured for healthcare in another state at its expense. When you register a UK-issued S1 with your local CPAM (caisse primaire d’assurance maladie, the local French health insurance fund), the United Kingdom remains the state competent for your sickness cover and reimburses France for your treatment. The official GOV.UK guidance on healthcare for British nationals living in France confirms the route: you obtain the S1 from the United Kingdom and you register it with the CPAM, after which you access French healthcare as an S1 holder rather than as a person insured under the French scheme. Keep that registration certificate safe, because it is the document on which everything else depends. Read the current procedure here: Healthcare for UK nationals living in France – GOV.UK.

The legal consequence follows from the coordination rules. Within the European system, and under the social security protocol of the EU-UK Trade and Cooperation Agreement after Brexit, a person is subject to the social security legislation of one state only at any given time. The French Cour de cassation stated the principle in these exact terms: Cour de cassation, deuxième chambre civile, 30 janvier 2025, pourvoi n° 22-22.464, “les personnes auxquelles ce règlement est applicable ne sont soumises qu’à la législation d’un seul État membre”. A single state means a single bill: if the United Kingdom is competent for your sickness insurance, France cannot add a second layer of social charges on top. The same judgment recalls that income received in a state other than the competent state must be subjected to contributions in the competent state, citing expressly the Court of Justice judgment De Ruyter of 26 February 2015 (C-623/13). The De Ruyter case is the foundation of the whole subject: Mr de Ruyter, a Dutch national working in the Netherlands but living in France, was charged French CSG and CRDS on his Dutch income, and the Court of Justice held that levies with a direct and relevant link to social security fall under the single-legislation rule, so France could not charge them to a person already subject to another state’s scheme. Your S1 is the practical proof that you are that person.

French statute law then converts the principle into an express exemption. Article L. 136-6 of the Social Security Code, which creates the CSG on income from capital (revenus du patrimoine: rental income, annuities, investment income, capital gains and similar items), provides in its paragraph I ter: article L. 136-6 du code de la sécurité sociale, “ne sont pas redevables de la contribution les personnes qui, par application des dispositions du règlement (CE) n° 883/2004 du Parlement européen et du Conseil du 29 avril 2004 sur la coordination des systèmes de sécurité sociale, relèvent en matière d’assurance maladie d’une législation soumise à ces dispositions et qui ne sont pas à la charge d’un régime obligatoire de sécurité sociale français.” The twin provision for investment products and property gains, article L. 136-7, contains the same exemption and adds the machinery: the paying institution does not withhold the contribution once the holder proves the position, and any undue withholding can be repaid by the payer or reclaimed from the tax administration. Read it here: article L. 136-7 du code de la sécurité sociale, “ne sont pas redevables de la contribution les personnes qui, par application des dispositions du règlement (CE) n° 883/2004 du Parlement européen et du Conseil du 29 avril 2004 sur la coordination des systèmes de sécurité sociale, relèvent en matière d’assurance maladie d’une législation soumise à ces dispositions et qui ne sont pas à la charge d’un régime obligatoire de sécurité sociale français.” Two conditions therefore decide your case, and both must be met on the relevant date: you come under another coordinated sickness legislation (your registered S1 proves this), and you are not chargeable to a compulsory French health scheme (no French employment, no PUMA affiliation as a French-insured person alongside the S1). The Cour de cassation gives evidential teeth to such certificates: a certificate issued by the designated institution of the competent state binds the institutions and courts of the state where the work is performed, even where they consider the conditions manifestly unmet, and disputes must go through the inter-institution dialogue procedure. That was said of an E 101 posting certificate, but the logic is the same family: Cour de cassation, deuxième chambre civile, 24 janvier 2019, pourvoi n° 17-20.191, “un certificat E 101 délivré par l’institution désignée par l’autorité compétente d’un Etat membre, au titre du deuxième texte, lie tant les institutions de sécurité sociale de l’Etat membre dans lequel le travail est effectué que les juridictions de cet Etat membre”. Do not surrender your S1, do not let it lapse without renewing it, and never accept an argument that a French form alone overrides a British certificate without the formal dialogue between institutions.

One boundary must be stated clearly, because confusing it loses cases. The exemption covers the CSG and CRDS on income from capital and on investment products. It does not exempt you from everything with the word social in it. Employment and replacement income are governed by article L. 136-1, which taxes persons who are both domiciled in France for income tax and chargeable to a compulsory French sickness scheme: article L. 136-1 du code de la sécurité sociale, “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”. If you work in France and pay into the French scheme, your salary follows the French rules regardless of your British passport. Likewise, the cotisation subsidiaire maladie (the PUMA top-up contribution for residents with little or no French professional income) is a different levy under article L. 380-2, aimed at persons covered by the French universal scheme: article L. 160-1 du code de la sécurité sociale defines the PUMA beneficiaries as persons working in France or residing there in a stable and regular way, “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”, and article L. 380-2 du code de la sécurité sociale charges the contribution to those persons. An S1 holder registered through the S1 is not a PUMA beneficiary in the relevant sense, which is exactly why the S1 route and the PUMA route must never be mixed in the same file. Recent litigation shows how strictly courts police these borders: the Paris social court had to decide whether a person covered only by private insurance could be charged the PUMA contribution (Tribunal judiciaire de Paris, pôle social, 25 janvier 2024, RG 22/02568), and the Nanterre social court dealt in January 2026 with contributions claimed on board members affiliated to another member state’s scheme (Tribunal judiciaire de Nanterre, pôle social, 7 janvier 2026, RG 23/01040). The lesson for your file is simple: one status, one proof, one set of rules. If you are an S1 holder, argue as an S1 holder from the first line to the last.

B. Which income the exemption covers, what still costs 7.5 per cent, and how the numbers work

The CSG on income from capital catches almost everything a British resident in France lives on besides a salary: furnished and unfurnished rental income (revenus fonciers and BIC for furnished lets), life annuity payments bought for consideration, dividends and interest, taxable capital gains on shares and on property, and several professional profits taxed as income but not subject to CSG on earnings. Your French tax notice lumps the social charges together, which is why the error hides so well: the notice shows one global rate, currently 17.2 per cent in the standard case (9.2 per cent CSG, 0.5 per cent CRDS and 7.5 per cent solidarity levy), and an S1 holder should in principle pay only the last slice. The administration confirms the arithmetic on its own international pages: persons affiliated to a compulsory social security scheme other than the French one are exempt from CSG and CRDS, and British residents keep that exemption even though the United Kingdom left the European Union on 1 January 2021, with only the 7.5 per cent solidarity levy remaining due (see impots.gouv.fr, non-resident social charges page). Service-public.fr states the same outcome in English for residents affiliated to another country’s compulsory scheme: no CSG and no CRDS, only the 7.5 per cent solidarity levy (see service-public.fr, social levies on wealth and investment income (English)).

Work through three everyday examples so you can check your own notice. First, rental income. Suppose you let a flat in Lyon and declare 12,000 euros of net rental profit. At the full 17.2 per cent, the social charges come to 2,064 euros; at 7.5 per cent, they come to 900 euros. The difference of 1,164 euros is the refund to claim for that year, and the same calculation repeats for every open year. Readers who let property will find the companion treatment of how France taxes the rent itself, and how the treaty credit works, in our guide to British rental income in France and the treaty credit; the present article answers the narrower social-charges question that the companion guide leaves open. Second, interest and dividends. A 5,000-euro interest payment suffers 860 euros of charges at the full rate against 375 euros at 7.5 per cent, a 485-euro difference, and the same logic applies to dividends before any treaty withholding is considered. Third, a property capital gain. On a taxable gain of 80,000 euros, the gap between 17.2 per cent (13,760 euros) and 7.5 per cent (6,000 euros) is 7,760 euros for a single disposal, which is why vendors should check the social-charges line of the notaire’s computation before signing, not after. These are illustrations, not assessments: your notice, your S1 dates and any French affiliation in the same year decide the real figure.

Three qualifications keep the claim honest. First, domicile for income tax still matters. The exemption assumes you are fiscally domiciled in France within article 4 B of the Tax Code, the provision that treats as domiciled persons who have their home, their principal stay, their professional activity or their centre of economic interests in France: article 4 B du 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”. Non-residents have their own regime, so state in your claim whether you claim as a French resident with a British S1 or as a non-resident, and do not mix the two lines of argument. Second, timing is assessed year by year. The administration requires the foreign affiliation to be effective on 31 December of the year the income was received or realised, with a special rule fixing the assessment date at realisation for gains under either of the two deferral regimes. A gap in S1 cover during the year can therefore cost you that year’s exemption, and backdating an S1 after the notice arrives is never as strong as continuous cover proved by the certificate itself. Third, mixed households are treated person by person. Where only one spouse holds an S1, the administration asks for the return to identify whose income is whose, including the taxable amount after the applicable allowance for micro-regime rents and annuities. File the split correctly at the return stage and you avoid the most common refusal ground, which is not the law but the paperwork.

II. Proving your S1 position and getting the overpaid charges back

A. The evidence file that wins: S1, dates, return entries and the paper trail

Start with the certificate. You need the S1 itself (or its renewal) covering the whole of each year claimed, the CPAM registration confirmation showing the date from which the French fund recognised you as an S1 holder, and proof that no competing French affiliation existed in the same period: no French payslips showing health contributions, no PUMA affiliation letter, no voluntary French cover overlapping the S1 dates. If you are a state pensioner, add the pension award letter linking the S1 to the pension; if you are a posted worker or a frontier worker, add the A1 or the employment documents showing which state is competent. Keep copies of every EHIC or GHIC linked to the S1, since they corroborate continuous cover. Where the S1 was renewed, keep the old and the new certificates side by side so that no gap appears unexplained. The administration’s own guidance makes the date the decisive fact, so build the file around dates first and amounts second.

Next, fix the return. If you have not yet filed for the year, complete the social-charges section of the income tax return so that the exemption is applied at assessment rather than reclaimed afterwards. The impots.gouv.fr page walks through the return entries, including the spouse-by-spouse split and the micro-regime amounts after allowance, and it warns that the affiliation must be effective at 31 December of the year concerned. If you already filed without claiming, or if the notice has arrived with the full 17.2 per cent, move to the contentious claim without delay. A claim by secure message (messagerie sécurisée) from your personal account on impots.gouv.fr is recommended by the administration itself, because it guarantees receipt; attach the S1, the CPAM confirmation, the tax notice showing the charges whose refund you seek, and a short computation year by year. State the legal basis in one sentence per text: article L. 136-6 I ter for income from capital, article L. 136-7 I ter for investment products and property gains, the single-legislation rule of article 11(1) of Regulation 883/2004 as recalled by the Cour de cassation on 30 January 2025, and the administration’s published position that British residents continue to benefit from the CSG-CRDS exemption with only the 7.5 per cent solidarity levy due. Short, dated and sourced beats long and indignant every time.

Watch the clock, because it runs without mercy. Claims for a refund of charges assessed by way of the income tax notice follow the standard contentious-claim time limits of the Livre des procédures fiscales (the Tax Procedure Book): as a rule, 31 December of the second year following the year of the event, which for charges on the return means the second year after the notice year. A 2023 notice is therefore typically challenged by 31 December 2025, and each year stands alone, so file year by year and never assume that winning one year automatically reopens the others. Keep proof of every sending date. If the administration stays silent for six months, the silence counts as an implicit rejection that you can take to the tribunal; do not wait for an express reply that may never come. And keep paying what is genuinely due in the meantime: the 7.5 per cent solidarity levy is not in dispute, and contesting the CSG-CRDS never justifies ignoring the rest of the notice. Interest for late payment on the undisputed part would eat your refund before you receive it.

B. Challenging a refusal, going to court, and the Paris and Ile-de-France practice points

If the administration rejects your claim, read the reasons before reacting. The three standard refusal grounds are interruption of cover (the S1 did not cover the whole year), competing French affiliation (a French payslip, a PUMA registration or French voluntary cover in the same year), and defective paperwork (S1 attached without the CPAM registration, or a joint return that does not say which spouse holds the S1). Each has a cure. A cover gap can sometimes be closed by asking the British issuing authority for a corrected or backdated certificate, but only where the underlying entitlement genuinely existed; a certificate manufactured after the event, without real cover, will collapse at the first inter-institution check. A competing French affiliation must be examined, not denied: if you briefly worked in France, the French scheme may indeed have been competent for that period, and the honest move is to limit the claim to the months of pure S1 cover rather than lose the whole year defending an unsustainable all-or-nothing position. A paperwork refusal is the easiest to fix, by refiling with the CPAM confirmation, the pension or employment link, and the spouse split set out line by line.

Where the rejection stands on the substance, the appeal goes to the administrative tribunal (tribunal administratif) for charges assessed with the income tax, with the standard two-month deadline running from the express rejection or from the expiry of the six-month silence period. Your application should plead, in order: the facts of cover (S1 plus CPAM registration, month by month), the two statutory conditions of articles L. 136-6 I ter and L. 136-7 I ter, the single-legislation principle of article 11(1) of Regulation 883/2004 as applied by the Cour de cassation on 30 January 2025 with its express reference to De Ruyter, the binding effect of certificates issued by the competent state’s institution as recalled on 24 January 2019, and the administration’s own published doctrine maintaining the exemption for British residents with only the 7.5 per cent levy due. Ask the tribunal, in the alternative, to stay the case and seek the inter-institution dialogue or a preliminary reference if the administration disputes the validity of your S1: the Nanterre court’s 2026 handling of affiliated-elsewhere arguments shows that judges take the single-legislation question seriously when it is properly documented, and a judge who sees a complete dated file is far readier to draw the consequences than one faced with bare assertions. Quantify the claim precisely, year by year and income by income, with the 17.2 per cent charged, the 7.5 per cent due, and the difference claimed, plus statutory interest from the claim date.

A short Paris and Ile-de-France note, because procedure has a geography. If you live in Paris or the inner suburbs, your file is handled by your local SIP (service des impôts des particuliers, the personal tax office) for the return and the first claim, and an appeal goes to the tribunal administratif de Paris or, for the outer departments, to Cergy-Pontoise, Melun or Montreuil according to your address. Two practical points matter here. First, Paris-based British residents very often have cross-border files (a London pension, a French flat, sometimes a brief French contract), so the competing-affiliation check deserves extra care before you claim: pull your relevé de carrière and your CPAM attestation de droits covering each claimed year and confirm that neither shows French health cover alongside the S1. Second, keep the tribunal competent and the file local: precinct shopping does not exist in tax litigation, and a claim sent to the wrong office loses weeks. None of this changes the substance, which is national, but in a jurisdiction where dockets move fast, a complete first filing is worth more than a brilliant second one.

Conclusion

A British S1 holder living in France should, in the standard case, pay 7.5 per cent of solidarity levy on income from capital and on investment products, not the full 17.2 per cent of social charges shown on an uncorrected notice. The rule rests on three solid legs: the single-legislation principle of Regulation 883/2004 recalled by the Cour de cassation on 30 January 2025, the express exemptions of articles L. 136-6 I ter and L. 136-7 of the Social Security Code, and the tax administration’s published confirmation that British residents keep the CSG-CRDS exemption after Brexit. The claim turns on proof, not nationality: a continuous S1, a CPAM registration, no competing French affiliation, and a year-by-year computation filed within the time limit. Check your earliest open notice today, because the oldest year is always the first to expire.