A British citizen who has settled in France after Brexit can receive an unexpected demand from URSSAF for a cotisation subsidiaire maladie (CSM), even when the income that appears to have triggered it came from the United Kingdom. The CSM is a French social-security contribution connected with access to the French health system. It is not the same as income tax, CSG or CRDS, and it is not automatically cancelled merely because the person has a British passport, a Withdrawal Agreement residence card or private medical insurance. The decisive questions are more precise: did you have stable and regular residence or another legal basis for French healthcare, did you have little or no French professional income, did you receive a pension, annuity or unemployment payment during the relevant year, and how did the French tax administration classify your property or investment income? This guide focuses on the difficult case of a British resident with UK rental income, dividends, investments or other capital income who is not relying on the S1 route as a pensioner. It explains how to separate a genuine CSM liability from a wrong classification, audit the calculation, preserve evidence and challenge the demand without losing the procedural deadline.
I. When does a British resident in France become liable for the CSM?
A. What do the French PUMa and CSM rules actually require?
France uses the expression protection universelle maladie, usually shortened to PUMa, for the universal health-protection framework. In practical terms, it gives a person who works in France or resides there on a stable and regular basis a route into French healthcare. The starting point is Article L. 160-1 of the French Social Security Code. Its opening sentence 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 dans les conditions fixées au présent livre.
The legal effect for an English-speaking reader is that healthcare rights and funding are assessed by reference to the French social-security system, not simply by nationality.
The CSM is the contribution designed for a person whose participation through French work income is absent or too low, while the person has sufficient income from assets or capital. URSSAF is the French network that calculates and collects many social-security contributions. A CSM notice therefore usually arrives from an URSSAF collection body rather than from the income-tax office. That administrative origin matters: the notice concerns a social-security debt, with its own evidence and challenge route, even though the calculation may have used figures transmitted by the tax administration.
For a British resident, Brexit changes the legal framework but does not create a blanket CSM exemption. A British citizen who lived in France before the end of the transition period may hold a Withdrawal Agreement residence document, often described in French as a titre de séjour carrying the words “Article 50 TUE/Article 18(1) Accord de retrait”. The French implementing Decree no. 2020-1417 of 19 November 2020 gives that document a role in residence, work and social rights. Its Article 30 links the relevant residence documents to affiliation and social benefits, subject to the conditions for each benefit. The card proves a status; it does not, by itself, answer whether a CSM was correctly calculated for a particular year.
The same distinction is important for an S1 certificate. An S1 is a portable healthcare entitlement document issued by the state responsible for a person’s healthcare costs, for example for some UK State Pension recipients. The official GOV.UK guidance on healthcare in France explains that a qualifying person must register the S1 with the local caisse primaire d’assurance maladie (CPAM), meaning the local primary health-insurance fund. An S1 can change which state bears healthcare costs and how a person is affiliated. It should therefore be checked before accepting that PUMa-based CSM rules apply. It is not, however, a reason to assume that every British resident is exempt: the issuing state, the benefit, the registration, the period and the person’s work and residence history all need to be proved.
Article L. 380-2 sets the CSM conditions. The statute begins: Les personnes mentionnées à l’article L. 160-1 sont redevables d’une cotisation annuelle lorsqu’elles remplissent les conditions suivantes :
It then looks at French professional income and the absence of certain replacement incomes. The relevant exclusion is expressed in the statute as follows: Elles n’ont perçu ni pension de retraite ou d’invalidité, ni rente, ni aucun montant d’allocation de chômage au cours de l’année considérée.
The wording is significant for British cases. The question is not whether a person describes themselves as retired, semi-retired or financially independent. The question is whether the person or, where the law requires it, the other member of the married or civil-partnership couple received one of the listed categories during the year used by URSSAF.
That produces four initial questions for a British resident:
- Was there a stable and regular French residence or another basis for French healthcare during the period?
- Were French professional earnings below the statutory threshold, including the relevant position of a spouse or partenaire lié par un pacte civil de solidarité, a civil-partnership partner under French law?
- Did the person receive any retirement or invalidity pension, annuity or unemployment payment in the relevant year?
- Did the household have the type and amount of property or capital income that can enter the CSM base?
Each question must be answered with dates and documents. A residence permit issued in 2022 cannot automatically prove the position for all of 2020. A private policy bought from a British insurer may show that the person tried to protect themselves against medical costs, but it does not automatically replace the French legal analysis. Conversely, an S1, a French employment contract, a UK posting certificate or another international-coordination document may show that the simple PUMa assumption was incomplete.
Do not confuse the CSM with CSG and CRDS. CSG means contribution sociale généralisée, the generalised social contribution, and CRDS means contribution pour le remboursement de la dette sociale, the contribution for repaying social debt. They can arise on pensions, investment income or other categories under different conditions. The public article on challenging CSG and CRDS on a UK State Pension where an S1 is involved addresses a different issue. A CSM bill headed “cotisation subsidiaire maladie” requires its own calculation and appeal. Reusing an argument about social charges on a pension without first classifying the CSM notice can lead to the wrong remedy.
There is also a recent statutory development that should be kept separate. Article L. 160-1-1 of the Social Security Code now addresses a possible financial participation for certain people resident in France without professional activity who are not liable for specified contributions under an international convention. The provision begins with a reservation for international conventions and European regulations. That mechanism is not the same legal charge as the CSM under Article L. 380-2. If a CPAM or another body mentions a “participation financière”, the British resident should identify the legal article and the issuing body instead of treating every health-related demand as a CSM.
B. Which UK income, residence and pension facts change the answer?
The CSM question often arises because a British household has moved its life to France while keeping its financial arrangements in the UK. Article L. 380-2 refers to property income, movable-capital income, chargeable gains and certain non-professional business income. It also contains a wider reference to means of existence and lifestyle elements that are not already captured through the tax-based categories. The statute expressly includes assets and income available in France or abroad. Therefore, the fact that rent is paid into a UK bank account or that dividends are paid by a UK company does not, on its own, remove the income from the French analysis.
For the tax classification, Article L. 380-2 refers to Article 1417 IV of the French General Tax Code. The official Article 1417 IV of the General Tax Code contains rules for determining the relevant net income and for adding back particular deductions, allowances, exempt items or gains. A UK rental figure may therefore need to be reconciled with the figure shown on the French return, not simply copied from a UK tax statement. The French tax administration’s English guidance on foreign-source income also explains that a French resident must use the applicable tax treaty and, where required, Form 2047. Tax treaty relief may prevent double taxation, but it does not automatically answer the separate social-security base question.
Typical items to examine include UK rental profit, dividends, interest, gains from selling shares, gains from an investment portfolio, distributions from a company, non-professional business receipts and income from property. The asset itself is not the same thing as the income produced by the asset. A bank balance, an ISA or a share portfolio should not be treated as an annual CSM income merely because it exists. On the other hand, a withdrawal, distribution or realised gain may be classified differently depending on the instrument, the date and the French tax treatment. A UK investment bond, pension wrapper, trust distribution and ordinary share account should never be placed in one generic “savings” line without identifying the legal nature of the payment.
Currency conversion is another common source of error. The French tax return records euro amounts. The official Form 2047 page confirms that the form is used for income received outside metropolitan France and the overseas departments. The supporting records should show the sterling amount, the payment date, the exchange-rate method used for the French return and the euro amount transmitted to the tax administration. A small exchange-rate difference may not change liability, but a full-year mismatch between gross rent, net rent, tax credit and bank receipts can materially change the amount labelled “A” in the CSM formula.
The current regulatory formula appears in Article D. 380-1 of the Social Security Code. The text states: Montant de la cotisation = 6,5 % × (A-0,5 × PASS) × [1-R/ (0,2 × PASS)]
. Here, A is the relevant property and capital income, within the statutory cap; PASS means plafond annuel de la sécurité sociale, the annual ceiling used in French social-security calculations; and R is the relevant French professional income. The same article says that the relevant income is retained up to eight times the annual PASS, that a part-year condition can lead to a pro-rata calculation and that the same period should not produce both the CSM under Article L. 380-2 and the separate contribution under Article L. 380-3-1.
The formula explains why a person with no French salary can receive a sizeable demand when capital income crosses the applicable lower threshold. It also explains why a person with some genuine French professional income may need a recalculation: the factor involving R reduces the amount as professional income rises. The notice should state the year, the income base and the rate or formula used. If it uses an old 8% calculation for a post-2018 period without explaining the applicable transitional rule, that is a point to investigate. Conversely, a British resident should not assume that every older notice is invalid simply because the current formula uses 6.5%.
A simple illustration shows the logic without replacing the year-specific calculation. Suppose the applicable PASS is represented by P, the relevant capital and property income by A, and French professional income by R. The first part of the base is A minus one half of P. The second factor is one minus R divided by one fifth of P. If R is zero, the second factor is one; if R approaches one fifth of P, the factor approaches zero. If the person was covered by the legal healthcare basis for only part of the calendar year, the result may be reduced pro rata. The real dispute is often not arithmetic but classification: whether the person was in the CSM population, whether the income belonged in A, whether a pension or international-coordination rule excluded the person and whether the period was correctly measured.
Household status can change the outcome. Article D. 380-5 provides for the tax administration to transmit the information used for calculating the relevant income and addresses income of spouses or civil-partnership partners reported jointly. If the notice has attributed all joint UK dividends or rent to one person, ask how the French return was filed and whether the legal sharing rule has been applied. A British couple may also have different statuses: one person may work in France, one may hold a UK pension, and one may have the investment account. A response should set out each person’s status rather than describe the couple as a single economic unit.
Residence timing must be treated with the same care. Article L. 160-1 looks to stable and regular residence, while the CSM calculation can be pro-rated under Article D. 380-1. Keep proof of the arrival date, departure date, principal home, French tax residence, health registration, employment and residence documents. Travel days alone do not always decide stable residence, and a tax-residence dispute is not automatically identical to a health-affiliation dispute. The evidence should explain the factual timeline and the legal basis for each month, not merely attach a passport full of entry stamps.
Finally, identify pension and annuity payments exactly. The exclusion in Article L. 380-2 uses legal categories. A UK State Pension is plainly relevant, but a private pension drawdown, an occupational scheme payment, a purchased annuity, a lump-sum withdrawal, an investment-bond payment and a trust distribution may not receive the same classification. Obtain the provider’s annual statement, payment dates, the nature of the product and any document showing whether the payment is a pension, an annuity or investment income. If the notice concerns a year in which any qualifying retirement or invalidity pension, annuity or unemployment amount was paid, that fact should be placed at the centre of the response.
II. How should a British resident challenge an URSSAF CSM bill after Brexit?
A. How should the calculation and evidence be audited?
Start with the notice, not with a general complaint about Brexit. Record the date on which it was received, the contribution year, the URSSAF reference, the amount, the payment deadline, the stated income source and any reference to a prior notice or formal demand. Article R. 380-4 states that the CSM is called, at the latest, on the last working day of November in the year following the year for which it is due, and that it is payable within thirty days of the call. The same article gives an important practical route: a person who considers the amount inaccurate may pay the amount they consider due on the basis of probative material sent to the collecting body, which can then confirm or correct the amount. That option must be handled with care where liability itself is disputed, but it shows why a detailed evidence pack is more useful than a bare denial.
Create a year-by-year reconciliation with separate columns for:
- French professional income for each member of the household;
- UK employment, self-employment, pension, annuity and unemployment payments;
- UK rent, dividends, interest, investment gains and other distributions;
- the amounts declared in France, including any Form 2047 entries;
- the sterling-to-euro conversion used for each relevant payment;
- the dates of French healthcare affiliation, S1 registration or another international basis;
- the amount used by URSSAF for A, the amount used for R, the PASS year and the formula applied.
Then compare the reconciliation with primary documents. The core pack will normally include the URSSAF call, any formal demand, French income-tax assessments, Form 2042 and Form 2047, UK HMRC statements, pension or benefit certificates, payslips, employment contracts, dividend vouchers, rental accounts, broker statements, bank entries, residence documents, CPAM correspondence and S1 registration evidence where relevant. If the dispute concerns a spouse or civil-partnership partner, include the joint return and documents showing the actual ownership or allocation of the income. If a French tax return was corrected after the CSM was calculated, attach the amended assessment or the tax office’s written position.
Check whether URSSAF used gross or net amounts consistently. The reference to Article 1417 IV means that the tax-derived base can include adjustments and add-backs. A treaty exemption for UK rent or a foreign tax credit may affect French income-tax liability without removing the amount from every social-security calculation. The correct argument may be that the amount was not income of a listed category, was attributed to the wrong person, was already included in another period, was below the relevant threshold, or was incorrectly converted. Avoid asserting that “the UK taxed it, so France cannot use it”: that statement confuses the allocation of taxing rights with the conditions for a French social-security contribution.
Check the health-affiliation premise separately. Ask CPAM for the legal basis and effective dates of the French healthcare rights. If the person had a registered S1, request written confirmation of the registration period and the person for whom the S1 was issued. If the person relied on an Article 50 residence document, attach it with proof of residence and explain the connection to the relevant healthcare period. If the person had private insurance only, identify the policy dates and benefits, but do not present the policy as a statutory exemption unless an applicable rule supports that position.
Check the legal year. The CSM framework changed in 2019, including the rate, ceiling and formula. The current Article R. 380-3 says that the contributions under Article L. 380-2 are calculated, called and collected by the competent bodies on the basis of information transmitted by the tax administration or by the liable persons. The current Article R. 380-4 sets the call and correction procedure. A calculation for an old year must be tested against the version in force for that year as well as against any later case law. A current formula cannot simply be pasted onto a 2016 notice, and a historical 8% decision cannot be used to calculate a 2026 liability.
There is a useful but limited line of recent case law. In Cour de cassation, Second Civil Chamber, 27 February 2025, no. 22-21.800, the Court rejected arguments that the historical mechanism breached property and equality protections. The decision records the historical structure in the words Il ressort des articles L. 380-2 et D. 380-1 précités que le taux de la cotisation subsidiaire maladie est fixé à 8 % des revenus du patrimoine
. That passage describes the rules applicable to the dispute, which concerned 2016; it is not a licence to replace the post-2019 6.5% formula with 8% for every notice. The case also confirms that a general proportionality objection is unlikely to succeed on its own. A factual calculation error, wrong status or wrong period is usually a more focused ground.
Data-transfer arguments also require precision. In Cour de cassation, Second Civil Chamber, 27 February 2025, no. 22-17.970, the Court accepted that tax information can be transmitted within the statutory framework and that the absence of an individual warning does not automatically cancel a post-2017 call. In the related published decision, no. 23-22.218, also of 27 February 2025, the Court stated: Doit donc être cassé l’arrêt qui annule l’appel de la cotisation subsidiaire maladie au motif que l’organisme de recouvrement n’a pas respecté son obligation d’information individuelle à l’égard du cotisant concernant le transfert de ses données fiscales à l’URSSAF
. A British resident should therefore request the data and correct it, but should not rely solely on the fact that no separate letter explained the tax-to-URSSAF transfer.
Timing arguments need the same discipline. In no. 22-22.437, Second Civil Chamber, 27 February 2025, the Court held that missing the regulatory last date for calling the contribution did not itself create a prescription bar. The decision says that the call date starts the thirty-day payment period and that only a call after the applicable limitation period would prevent recovery. That is why a late November or December letter should be analysed, not celebrated as an automatic cancellation. Check the exact year, the date of receipt, the applicable limitation rule, the formal nature of the document and whether the issue concerns a call, a reminder, a mise en demeure (formal demand to pay) or a later recovery act.
The fairness argument can still matter in a properly evidenced case. In no. 23-15.218, Second Civil Chamber, 27 February 2025, the Court examined the complaint that the historical CSM was confiscatory and held that the statutory contribution was connected with the financing of health cover and did not have an excessive character in the dispute before it. That makes a blanket “the amount is unfair” submission weak. A well-supported submission can instead show that the person never met the statutory conditions, that qualifying pension or international status was ignored, that the capital figure is wrong, that the same income was counted twice, or that the amount was calculated under the wrong annual rules.
Use the evidence to produce a short calculation schedule as well as a narrative letter. Label every attachment, cite the page on which the relevant figure appears and state the exact correction sought. If the requested result is zero, explain why: for example, a qualifying pension was paid, a registered S1 or another convention-based basis applied, the person did not have stable and regular French residence for the full period, French professional income was above the relevant threshold, or the supposed capital income was a principal repayment rather than income in a listed category. If the requested result is a reduced amount, show the proposed A, R, PASS and pro-rata period. That format gives URSSAF a decision it can actually make.
B. Which appeal, deadline and court route should be used?
Send the first challenge to the URSSAF body identified on the notice using a channel that proves delivery. The notice may provide an online account, a postal address or a specific upload route. Keep the submitted PDF, the transmission receipt and the complete attachment list. Ask for the calculation sheet, the tax data used, the period of affiliation, the category of each item in A, the figure for R, the PASS used and the legal basis for treating the person as liable. A request for information does not necessarily suspend every deadline, so the letter should clearly say that it is a formal challenge and should be sent within the period stated in the notice.
The ordinary social-security route includes a commission de recours amiable (CRA), meaning the body that examines an amicable prior appeal within the social-security organisation. Article L. 142-4 of the Social Security Code provides that contentious proceedings in the matters covered by the code are preceded by a prior appeal, subject to the statutory exceptions. The current Article L. 142-4 should be read with the implementing rules and with the wording of the notice. The current Article R. 142-6 states that, where a decision has not been brought to the claimant’s knowledge within two months, the person may treat the request as rejected; it also explains when the two-month period runs if documents are supplied later. This is not a reason to wait: a silent CRA response must be diarised and the next court deadline checked.
Ask the notice whether the first letter itself is the CRA appeal or whether it is an invitation to correct the CSM under Article R. 380-4 before a formal prior appeal. Different documents can carry different instructions. If the letter is a mise en demeure, a recovery notice or a formal enforcement act, the response must address that document and its specific remedy. Article R. 380-7 provides that, after the relevant due dates, the collection body sends a formal demand by a method proving the date of receipt and gives a period to regularise. The official text of Article R. 380-7 is therefore useful when checking whether a later demand followed the required sequence, but it does not replace reading the notice actually received.
If the CRA rejects the challenge, or if the applicable rules treat the request as rejected after the statutory period, the dispute will generally move to the judicial social-security court, now the competent chamber of the tribunal judiciaire. Article R. 142-10 states that the territorially competent tribunal is normally the court for the applicant’s residence, with specific rules for a person living abroad. See the official Article R. 142-10 text before filing. A British resident in France should identify the tribunal for the French address and preserve proof of the CRA filing and decision. The court file should contain the original demand, the full calculation, the prior appeal, the response, the evidence and a concise statement of the requested relief.
Do not treat a French tax complaint as a substitute for the CRA process. If the underlying French tax assessment contains the wrong UK income, make the appropriate correction request to the tax administration as well, using the route applicable to that assessment. In parallel, tell URSSAF that the tax figure is disputed and provide the provisional evidence. The two administrations may have different records and deadlines. A successful tax correction may help the CSM calculation, but URSSAF’s collection challenge must still be preserved.
The 2025 case law also shows why a British resident should select the ground carefully. In no. 23-22.218, the Court rejected the proposition that the lack of individual information about the fiscal-data transfer automatically invalidated the call. In no. 22-22.437, a late call date alone did not amount to prescription. In no. 22-21.800 and no. 23-15.218, broad equality and property objections did not carry the cases. Those decisions do not prevent a successful challenge based on a pension exclusion, an S1 or convention-based affiliation, a wrong residence period, misclassified UK income, an incorrect joint allocation, a duplicate assessment or a failure to apply the correct year’s formula. They simply make the need for a documented, targeted ground clearer.
A practical CRA letter can follow this order:
- identify the person, URSSAF reference, contribution year and date of receipt;
- state that the CSM call is challenged in full or in a specified amount;
- state the legal grounds in separate paragraphs, without mixing residence, income and procedure;
- provide the corrected timeline and calculation;
- list the evidence and explain what each document proves;
- request cancellation, discharge or recalculation and repayment where a sum has already been paid;
- request a written decision and keep proof of delivery.
If the amount is large, if enforcement is threatened, or if the notice concerns several years, obtain advice before making a payment or signing a repayment arrangement. Payment may be strategically sensible in some cases to limit recovery consequences, but it should not be treated as an admission if the liability is disputed. Any payment letter should reserve the right to seek recalculation or repayment and should identify the legal challenge already filed.
For British residents, the strongest evidence is usually a coherent cross-border timeline. Put the UK and French facts on the same page: when you moved, when your French healthcare rights began, whether an S1 was registered, what work you did, what benefits or pension you received, when each UK payment arrived, what was declared in France and when URSSAF issued the call. The question “why has France charged me?” becomes answerable when each legal condition is mapped to a date and a document. It may reveal a genuine CSM, a reduced CSM or no CSM at all.
Conclusion
A CSM demand sent to a British resident after Brexit is not resolved by nationality, the presence of a UK bank account or the existence of private insurance. The analysis begins with the French healthcare basis and the precise Article L. 380-2 conditions. It then turns to the UK pension, annuity and benefit history, the household’s French and foreign capital income, the applicable PASS and formula, the residence period and the evidence used by the tax administration. The post-2019 formula, the correction mechanism under Article R. 380-4 and the recent Cour de cassation decisions make a precise audit more useful than a general objection to the principle of the contribution. Act quickly, preserve the notice and proof of receipt, request the underlying data, file the applicable prior appeal and keep the court route open if URSSAF maintains the demand.
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