You have lived in France for three years since Brexit. Your healthcare is covered because Britain still pays for it: you registered a British S1 form with your local CPAM office, the French health insurance fund, and you hold a carte Vitale like your French neighbours. Then the autumn post arrives, and with it your avis d’impot, the French tax bill for your rental income or your savings interest. At the bottom of the calculation, below the income tax itself, sit three lines you did not expect: contribution sociale generalisee at 9.2 percent, contribution au remboursement de la dette sociale at 0.5 percent, and prelevement de solidarite at 7.5 percent, seventeen point two percent in total on income that Britain already had a hand in. If your healthcare depends on the British system and not the French one, two of those three lines should not be there at all. Only the 7.5 percent solidarity levy is genuinely due. The difference, nine point seven percent of every euro of capital income, is money you can claim back, provided you move within the legal deadline and with the right proof. This guide explains, for a British reader with no French legal training, which levies apply to you, why the S1 exempts you from two of them, how to calculate the correct bill, and how to challenge the overcharge step by step.

I. You Live in France and Britain Pays for Your Healthcare: Why That Changes Your French Social Levies

A. How do I know France taxes my capital income and which three levies sit on the bill?

France taxes you on worldwide income once you become fiscally domiciled here. The test sits in article 4 B of the French Tax Code, which treats as domiciled in France persons who have here their home or their principal place of stay, persons who carry on a professional activity here, and several other categories. Most British retirees and remote residents who settled after Brexit meet the first test within months: their foyer, their actual home, is in France. From that moment, French tax residents must declare not only salaries and pensions but also revenus du patrimoine, meaning income from capital and property: French rental income from a gite or a long-term let, interest and dividends, and capital gains on securities. Each of these is first taxed to income tax, then hit a second time by what the French call prelevements sociaux sur les revenus du patrimoine, social levies on capital income. Do not confuse them with social security contributions on wages. They are tax-like charges collected with the income tax, and they appear on the same bill.

The legal base for the main levy sits in article L. 136-6 of the Social Security Code, which makes persons domiciled in France liable to a contribution on capital income assessed on the net amount used for income tax, and lists rental income, life annuities for consideration, investment income, capital gains and several business profits. A sister provision, article L. 136-7 of the same code, does the same work for produits de placement, meaning investment products collected at source such as bond interest and similar payments. On top of these two contributions come the contribution for the repayment of the social debt, universally called the CRDS, and the prelevement de solidarite, the solidarity levy. The official rates, published on the justice.fr public information sheet, are simple: CSG 9.2 percent, CRDS 0.5 percent, solidarity levy 7.5 percent, total 17.2 percent. Take a concrete example. A British couple living near Bergerac lets out a second cottage for a net taxable rental profit of 12,000 euros. At 17.2 percent, the social levies on that profit reach 2,064 euros. If only the solidarity levy is genuinely due, the correct figure is 900 euros, and 1,164 euros has been overcharged. On a 40,000 euro capital gain on shares, the overcharge rises to 3,880 euros. These are not rounding errors. They are systematic overcharges on a precise category of taxpayers, and the S1 holder is the archetype.

One common misunderstanding must be cleared up at once. This mechanism concerns capital income, not the pension itself. A British state pension or private pension paid to a French resident is taxed under the France-United Kingdom double tax treaty and the pension articles of the Tax Code, a different corridor with its own social treatment. What the S1 changes, as explained below, is the fate of the CSG and CRDS lines on capital income: rental profits, interest, dividends and gains. If your bill shows 17.2 percent on those items while you hold a valid S1, the CSG and CRDS lines are contestable. The 7.5 percent solidarity line is not. Knowing which line is which is the first step, because the tax office will not do the sorting for you, and a challenge that attacks the whole 17.2 percent, including the solidarity levy, fails on the one point it should never have raised.

The second misunderstanding concerns nationality. The exemption has nothing to do with being British and everything to do with where your health cover sits. A British resident affiliated to the French health system through PUMA, the French universal health protection, pays the full 17.2 percent like a French national. A French national working in London and covered by the British National Health Service escapes the CSG and CRDS on the same basis. The passport is irrelevant. The S1 form, the certificate by which Britain confirms it pays for your French healthcare, is everything. Keep that idea in mind, because every proof you will gather serves a single purpose: showing the tax office that for health insurance you belong to the British system and cost the French system nothing.

B. Why does my British S1 exempt me from CSG and CRDS but never from the 7.5 percent solidarity levy?

The answer starts in European law, which still governs your situation through the Brexit Withdrawal Agreement. The coordination regulation for social security, regulation 883/2004 of 29 April 2004, lays down a principle of single applicable legislation: a person covered by the coordination system answers to the social security legislation of one Member State only. The French Court of Cassation restated it word for word in two 2025 rulings: read the ruling of 25 September 2025, appeal 22-24.634, and the Court repeated the formula the same day when it held that the 883/2004 regulation and the 1408/71 regulation it replaced enshrine, and I quote, “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)”. In plain English: someone insured for sickness in one Member State must not pay into the sickness system of another. The Court of Justice decided exactly this in the De Ruyter case on 26 February 2015, case C-623/13, when it held that French CSG and CRDS on capital income are functionally social security contributions caught by the single-legislation rule, so a person insured in another Member State cannot be charged them. The second September 2025 ruling, appeal 22-20.036, rejected on the same day, confirms the line: where there is no reasonable doubt about the interpretation of Union law, there is no need to ask Luxembourg again, and the Court dismissed the appeals, and I quote the operative part, “REJETTE le pourvoi”. The principle is therefore settled at the highest French level, and it is this principle the statute now carries.

After De Ruyter, the French Parliament wrote the exemption into the statute rather than fighting it case by case. That is the paragraph every S1 holder should know. Article L. 136-6, paragraph I ter, of the Social Security Code provides, and I quote exactly: “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.” In plain English: persons who, under regulation 883/2004, answer for sickness insurance to a coordinated foreign legislation and are not covered by a compulsory French scheme do not owe the contribution. If your S1 is registered with the CPAM and you are not simultaneously affiliated to a French compulsory scheme for the same risk, you match this description letter for letter. The same paragraph exists for investment products under article L. 136-7. This is not a tolerance or a favour. It is a statutory exemption, and the tax computer that prints 17.2 percent on your bill has simply not been told about your S1.

But the solidarity levy follows the opposite rule, and this is where many reclaim attempts collapse. Article 235 ter of the French Tax Code creates a solidarity levy on capital income and on investment products, collected under the same rules as the CSG, and then adds the decisive phrase, and I quote: “sans qu’il soit fait application du I ter du même article L. 136-6”, meaning without applying the I ter exemption. The same article then fixes the rate, and I quote: “Le taux des prélèvements de solidarité mentionnés au I est fixé à 7,5 %.” So the solidarity levy deliberately survives the S1. The official guidance says the same in everyday language: where you live in France but answer to a foreign compulsory scheme, you are not subject to CSG and CRDS and only the 7.5 percent solidarity levy is due. The tax administration confirms the Brexit point explicitly for British readers: although the United Kingdom left the European Union on 1 January 2021, British residents continue to benefit from this CSG and CRDS exoneration, the administration confirms in its own guidance that British residents keep this CSG and CRDS exoneration despite the United Kingdom having left the European Union on 1 January 2021, adding that the income remains subject to the solidarity levy at 7.5 percent. On the British side, the practical companion is the GOV.UK guidance on healthcare for British nationals living in France, which explains obtaining and registering a British-issued S1 form with the local CPAM office, the step that makes the whole exemption possible.

Two practical consequences follow. First, the target of your challenge is precise: the CSG line at 9.2 percent and the CRDS line at 0.5 percent, together 9.7 points, and nothing else. Never ask for the solidarity levy back. Asking for it back signals that you have not understood the mechanism and weakens the credible part of the claim. Second, the exemption is conditional on effective affiliation. The administration states the timing rule plainly: affiliation must be effective on 31 December of the year in which the income was received or realised, the administration requiring affiliation to be effective on 31 December of the year in which the income was received or realised. An S1 obtained in March of year N covers the income of year N. An S1 first registered in January of year N+1 does not retrospectively clean the income of year N. If your S1 lapsed for part of the year because you took French employment and joined the French scheme, that part of the year is outside the exemption. Before writing any letter, fix the calendar: S1 valid, registered with the CPAM, covering 31 December of the tax year. Everything else is paperwork.

II. Your Bill Shows the Full 17.2 Percent: How to Calculate, Prove and Recover the Overcharge

A. How do I calculate what I really owe and which proof will the tax office accept?

Start from the bill, not from estimates. Take your avis d’impot for the year concerned and isolate, within the prelevements sociaux block, the three amounts: CSG, CRDS and prelevement de solidarite. Check the income base they apply to, usually your net rental profit after charges, your interest aftertyping, or your taxable gain. Recompute each line from the verified rates: 9.2 percent, 0.5 percent and 7.5 percent. The sum should equal 17.2 percent of the base. Your correct bill, as an S1 holder affiliated only in Britain, is the 7.5 percent line alone. The reclaimable amount is the CSG plus CRDS lines, 9.7 percent of the base. Worked example with the Bergerac cottage: base 12,000 euros, CSG 1,104 euros, CRDS 60 euros, solidarity 900 euros, total charged 2,064 euros. Reclaimable: 1,164 euros. Keep this one-page calculation. It becomes the annex to your complaint, and it shows the officer within thirty seconds that you are asking for the right lines only, which is how files get processed instead of parked.

Next, assemble the proof pack before you write anything. The tax office does not know your health cover, and the CPAM does not talk to the tax computer. You must bridge the two. The pack has four layers. First, the S1 itself and the CPAM registration certificate, the attestation de droits, showing cover for the whole year including 31 December. If you only have the S1, ask the CPAM for a dated attestation covering the year. Second, proof that Britain funds the cover: the S1 is issued for state pensioners, for recipients of exportable benefits, and for posted workers and their families, and the GOV.UK guidance describes each route. Add any accompanying letter from the competent British institution, the NHS Business Services Authority for pensioners or HMRC for posted workers with an A1 certificate. Third, proof of non-affiliation to a French compulsory scheme for the same risk over the same period: no French payslips, no PUMA contributions bill, no attestation from a French caisse. If you were briefly employed in France during the year, say so honestly and restrict the claim to the months outside French affiliation, because a partial claim paid quickly beats a full claim destroyed by one payslip. Fourth, the tax documents: the avis d’impot showing the levies, the relevant declaration pages, forms 2047 for foreign income and 2042 with its annexes, and your calculation sheet. The administration’s reclaim page tells non-residents and cross-border cases to attach the full supporting set, and I quote the instruction in substance: you must join all necessary supporting documents, proof of affiliation and the tax notice showing the social levies whose refund is requested. A file with the S1, the CPAM attestation, the avis and the calculation is complete. A file with only a letter is a delay.

Three frequent traps deserve a warning because each turns a winning file into a losing one. Trap one: the unregistered S1. An S1 form sitting in a drawer, never presented to the CPAM, proves nothing about French cover. Registration with the CPAM is the act that moves you into the British-funded lane, so register first, obtain the attestation, then claim. If you have not yet registered your form, read our step-by-step guide to registering a British S1 with the CPAM and obtaining the carte Vitale before starting the tax challenge below. Trap two: the mixed year. Posted workers sent temporarily by a British employer keep British cover and use the S1 or an A1, but workers who become locally employed in France join the French scheme and lose the exemption from that date. Claiming the full year when three months belong to France invites a total rejection instead of a partial grant. Trap three: attacking the solidarity levy. The 7.5 percent is due by statute even for S1 holders, as article 235 ter states by excluding the I ter exemption. Demanding it back marks the letter as legally uninformed. Claim the 9.7 points, concede the 7.5, and cite the two articles side by side. That contrast, exemption here and deliberate non-exemption there, is precisely what convinces a verifying officer that you have read the law.

A final calculation point for landlords and investors with several income types. The exemption applies levy by levy and income by income, but the affiliation test is global to the person for the year. If your S1 covered the whole year, the CSG and CRDS fall away on the French rental profit and on French-source interest and gains alike. If it covered only part of the year, French case law on neighbouring social contribution disputes applies yearly logic with care, and the safest presentation is to claim the full-year exemption only when the S1 covered 31 December and the whole year, and to pro-rate or restrict the claim with an explanation otherwise. Attach a short timeline table: month by month, British cover or French cover, with the document for each change. Officers process timelines. They reject narratives.

B. How do I challenge the bill within the deadline and get the money back?

French tax procedure imposes an order you cannot skip: first a written complaint to the tax office, the reclamation, and only afterwards the court. Article R*190-1 of the Tax Procedure Book states the rule, and I quote: “Le contribuable qui désire contester tout ou partie d’un impôt qui le concerne doit d’abord adresser une réclamation au service territorial, selon le cas, de la direction générale des finances publiques ou de la direction générale des douanes et droits indirects dont dépend le lieu de l’imposition.” In practice this means a reclamation contentieuse sent to the service des impots des particuliers of your French address, or for taxpayers managed offshore to the non-resident service. The administration expressly allows the secure messaging channel of your online personal account, and its reclaim page confirms that a message through the messagerie securisee guarantees proper receipt. Send it that way and keep the acknowledgement. A letter sent only to the CPAM, to the British authorities or to an MP is not a reclamation and stops no deadline.

The deadline is the one taxpayers miss most often, so read it twice. Article R*196-1 of the Tax Procedure Book requires complaints about most taxes to reach the administration no later than 31 December of the second year following, depending on the case, the collection of the tax roll or the payment of the tax where no roll was issued, and I quote the operative words: “doivent être présentées à l’administration au plus tard le 31 décembre de la deuxième année suivant celle, selon le cas : a) De la mise en recouvrement du rôle ou de la notification d’un avis de mise en recouvrement”. For social levies billed on the income tax roll, the clock normally starts with the collection of the roll for that year’s income. Example: levies on 2023 income rolled in autumn 2024 must be challenged by 31 December 2026. Levies on 2024 income rolled in 2025 run to 31 December 2027. File per year, one reclamation per avis, and never merge several years into a single undated letter, because each roll has its own deadline and a merged letter risks being booked to the wrong one. If the deadline has already passed for the oldest year, claim the later years anyway and say so explicitly rather than abandoning everything.

The content of the reclamation decides its fate. A good letter has five blocks on two pages. Block one identifies the tax: year, notice number, amounts of CSG and CRDS contested, and the income base. Block two states the legal basis in two moves: the exemption under article L. 136-6 I ter for persons under regulation 883/2004 not covered by a French compulsory scheme, and the deliberate survival of the 7.5 percent solidarity levy under article 235 ter, which you do not contest. Block three states the facts: British S1, registered with the CPAM on a given date, covering the whole year, no French compulsory affiliation, with the Brexit confirmation that British residents keep the exoneration. Block four does the maths: base times 9.2 plus base times 0.5 equals the refund requested, with the calculation annexed. Block five lists the annexes and asks expressly for a degrevement, a discharge, of the contested CSG and CRDS with compensating payment or restitution. Close with a sentence inviting the office to request any missing proof within a stated delay. This structure mirrors how the verifying officer must draft the decision: tax, law, facts, figures, order. Letters that follow it get decided. Letters that tell a life story get filed.

If the office rejects the claim expressly or stays silent for six months, the silence counts as an implied rejection and you may go to the administrative court, the tribunal administratif of your French home, within two months of the express or implied decision. Do not go to the social security court for a tax-roll dispute: the Cassation rulings quoted above come from social contribution litigation against the URSSAF and matter here as the authoritative statement of the single-legislation principle, but a challenge to levies collected on a tax roll follows the tax track, reclamation then administrative court. Before the court, the same file returns in litigious dress: the S1, the CPAM attestation, the avis, the calculation, the reclamation and its receipt, and the two statutes side by side. Ask the court for discharge of the CSG and CRDS, statutory interest, and costs. Most well-documented S1 files never reach a hearing because the administration grants the degrevement at the reclamation stage. The files that lose are the ones with an unregistered S1, a missed 31 December deadline, or a claim that wrongly includes the solidarity levy. Avoid those three faults and the procedure does the rest.

For readers who manage French tax from Britain after leaving France, the same logic applies through the non-resident service with one adaptation: French-source rental income and gains remain exposed to the levies, the S1 exemption still turns on effective affiliation to a foreign compulsory scheme at the relevant date, and the reclamation travels through the secure message channel or by post to the non-resident tax office with the same proof pack. The administration’s own reclaim page describes exactly this channel and warns that heavy volumes extend processing times, so file early in the deadline window rather than in December, and keep copies of everything until the refund lands.

Conclusion

A British S1 holder living in France after Brexit sits in a precise legal lane: French tax resident for income, British-insured for sickness, exempt from French CSG and CRDS on capital income by statute, and liable only for the 7.5 percent solidarity levy that Parliament deliberately kept. The overcharge is mechanical, the correction is documented, and the route is signposted: calculate the 9.7 points, prove the S1 with the CPAM attestation, file a reclamation before 31 December of the second year, and escalate to the administrative court only if the office refuses or stays silent. The two Court of Cassation rulings of 25 September 2025 anchor the principle at the highest level, the impots.gouv.fr confirmation protects British residents specifically after Brexit, and the rates are public and undisputed. Check your last avis tonight. If it shows the full 17.2 percent on rental income, interest or gains while your S1 covered the year, the CSG and CRDS lines are recoverable, and the only question is whether you claim them before the deadline closes.