You bought a stone cottage in the Dordogne, a flat near the coast in Brittany or a village house in the Luberon years ago, when Britain was still in the European Union. Life has moved on, the house is used a few weeks a year, and you have decided to sell. The estate agent has found a buyer, the notaire (the French public officer who authenticates property sales) names a figure for tax to be taken on the day of signing, and a second question follows at once: will HM Revenue and Customs tax the same profit again in Britain? Since Brexit you are a third-country national in France, the French administration treats your file differently from a Parisian seller, and every figure on the completion statement deserves to be checked. This guide explains, in order, how France calculates the taxable gain on your French second home, what is collected at source when you live in Britain, how the France-United Kingdom double tax treaty prevents you paying twice, when a British S1 healthcare certificate cuts the French social charges, and which remedies exist when the bill looks wrong.

I. How France taxes the sale of your French second home after Brexit

A. How is the taxable gain calculated and which holding-period taper applies?

French tax law starts from a wide net. Article 150 U of the French General Tax Code (Code général des impôts) provides that “les plus-values réalisées par les personnes physiques ou les sociétés ou groupements qui relèvent des articles 8 à 8 ter , lors de la cession à titre onéreux de biens immobiliers bâtis ou non bâtis ou de droits relatifs à ces biens, sont passibles de l’impôt sur le revenu dans les conditions prévues aux articles 150 V à 150 VH .” (CGI, art. 150 U, Légifrance). In plain English: gains made by individuals on the sale for value of built or unbuilt property, or of rights over such property, are liable to income tax under the rules of articles 150 V to 150 VH. Your holiday home falls squarely inside that definition, because the main-home exemption does not help you: the administration’s non-resident guidance states plainly that a non-resident cannot benefit from the exemptions linked to the main residence (impots.gouv.fr, Bien ou vendeur hors de France).

The starting point of the arithmetic is simple. Article 150 V provides that “La plus ou moins-value brute réalisée lors de la cession de biens ou droits mentionnés aux articles 150 U à 150 UC est égale à la différence entre le prix de cession et le prix d’acquisition par le cédant” (CGI, art. 150 V, Légifrance). The gross gain is the sale price minus the purchase price paid by you, the seller. Each side of that subtraction is then adjusted exactly as the statute allows, and this is where British sellers lose or save thousands. On the purchase side, the price you paid can be increased by the real acquisition costs (the frais de notaire, meaning registration duties and the notaire’s fee) or by a statutory flat-rate allowance where the conditions are met, and by documented works: building, rebuilding, extension or improvement works carried out by a business and supported by invoices, subject to a five-year holding condition for the flat-rate uplift. On the sale side, the price is reduced by the costs of the sale itself, such as agency commission you paid and certified diagnostics. Keep every invoice from the day you buy, because fifteen years later the notaire can only add what paper proves.

The second mechanism is the holding-period taper, called in French the abattement pour durée de détention: a percentage knocked off the gross gain for each year you owned the property. The current scale, confirmed by the administration’s official commentary, runs as follows for income tax: 6 per cent for each year of ownership beyond the fifth and up to the twenty-first, then 4 per cent for the twenty-second year, with full income-tax exemption once ownership exceeds twenty-two years (BOFiP, RFPI-PVI-20-20). For the social levies the taper is slower: 1.65 per cent per year beyond the fifth and up to the twenty-first, 1.60 per cent for the twenty-second year and 9 per cent per year beyond, with full exemption once ownership exceeds thirty years (same source). A concrete example makes this vivid. Suppose you bought in 2008 and sell in 2026, after eighteen full years of ownership: thirteen years beyond the fifth give thirteen times six per cent, or seventy-eight per cent off the gain for income tax, while the social-levy taper gives thirteen times one point six five per cent, about twenty-one per cent. The same sale is therefore nearly free of income tax yet still heavily charged to social levies, and that asymmetry surprises many British vendors.

Older sales were judged under different scales, which still matters if you are challenging an old assessment. In a decision of 9 September 2020 the Conseil d’État recalled the wording then in force: “La plus-value brute réalisée sur les biens ou droits mentionnés aux articles 150 U, 150 UB et 150 UC est réduite d’un abattement de 10 % pour chaque année de détention au-delà de la cinquième” (CE, 9 Sept. 2020, No. 436712, Légifrance). That case concerned a sale of 28 June 2012, and the court described the file in these terms: “M. D… C… a demandé au tribunal administratif de la Réunion de prononcer la décharge de la cotisation supplémentaire d’impôt sur le revenu et de contributions sociales mise à sa charge au titre de l’année 2012, procédant de la taxation de plus-value de cession immobilière qu’il a réalisée le 28 juin 2012” (same decision). The lesson for you is practical: identify the scale that belongs to the year of your sale, count your years of ownership from the acquisition deed, and check the notaire’s computation line by line. Very large gains can also attract an additional tax on high property gains (taxe sur les plus-values immobilières élevées), which the administration describes as applying in qualifying cases on top of income tax and social levies (impots.gouv.fr).

Two household situations deserve an early warning. If you own the house through a French property company of the family type, the société civile immobilière (a non-trading company whose purpose is to own and manage property), the main-home and several other personal exemptions are unavailable: the administration states that the non-resident relief is unavailable where the property is held through a legal entity such as an SCI (same source). And if you inherited the house or received it by gift, your acquisition price is normally the value declared in the succession or gift deed, which changes the whole subtraction. A short meeting with the notaire before the preliminary contract (compromis de vente) lets you fix the figures while there is still time to find missing invoices.

B. You now live in Britain: does France still collect tax at the signing and which papers will the notaire ask for?

Yes. France taxes the land first, wherever the vendor lives. The General Tax Code treats gains on French land as French-source income: article 164 B states “Sont considérés comme revenus de source française : a. Les revenus d’immeubles sis en France ou de droits relatifs à ces immeubles” (CGI, art. 164 B, Légifrance), and it lists among French-source items “Les plus-values mentionnées aux articles 150 U , 150 UB et 150 UC ,” where they relate to property situated in France, in the words of the statute, “lorsqu’elles sont relatives : 1° A des biens immobiliers situés en France ou à des droits relatifs à ces biens” (same article). Because the gain is French-source, the non-resident levy applies to you. Article 244 bis A provides: “Sous réserve des conventions internationales, les plus-values, telles que définies aux e bis et e ter du I de l’article 164 B , réalisées par les personnes et organismes mentionnés au 2 du I lors de la cession des biens ou droits mentionnés au 3 sont soumises à un prélèvement selon les taux fixés au III bis” (CGI, art. 244 bis A, Légifrance). That withholding-style levy (prélèvement) is collected through the notaire on the day of the authenticated sale, out of the price, before the balance reaches you.

The administration’s non-resident page explains the practical circuit: for a building sale, a return known as déclaration n° 2048-IMM must be filed, and after taper relief the gains of individuals and partnerships are subject to the levy at the single rate of 19 per cent (impots.gouv.fr). Treat that nineteen per cent as the figure the administration publishes for individuals and partnerships, and ask the notaire to confirm the current rate in the official commentary (Bulletin officiel des finances publiques, known as BOFiP) on the day of your sale, because rates and social-levy tables move while guidance pages are not always re-dated. The same page warns that you must appoint a tax representative where you live outside the European Economic Area, apart from Liechtenstein, and the sale price exceeds 150,000 euros (same source). Since Brexit, Britain is outside the European Economic Area, so for a sale above one hundred and fifty thousand euros you must appoint a tax representative (représentant fiscal): an accredited professional who signs the 2048-IMM declaration with the notaire, answers the tax office’s questions and remains liable for the levy. His fee is a normal cost of a British sale, and his appointment must be arranged weeks before completion, not discovered at the signing table.

Brexit changed more than the representative. When Britain was in the Union, British vendors shared the European rules on social levies and on the free movement of capital; today they are nationals of a third State, and that status can cut both ways. In a 2018 case the Conseil d’État had to ask the Court of Justice of the European Union whether a difference in social-levy treatment was compatible with the free movement of capital, formulating the question as follows: “La circonstance qu’une personne affiliée à un régime de sécurité sociale d’un Etat tiers à l’Union européenne, autre que les Etats membres de l’Espace économique européen ou la Suisse soit soumise, de même que les personnes affiliées à la sécurité sociale en France, aux prélèvements sur les revenus du capital prévus par la législation française entrant dans le champ du règlement du 29 avril 2004” could constitute a restriction on capital movements (CE, 5 Mar. 2018, No. 397881, Légifrance). You do not need to master that litigation: the point is that European protections you once enjoyed as of right must now be checked text by text, treaty by treaty. Your file at the notaire’s office should therefore contain your passports and birth certificates, the acquisition deed and all works invoices, proof of the years the house was at your free disposal, your British tax residence position, your S1 healthcare certificate if you hold one, and the appointment letter of the tax representative where the price exceeds the threshold. A file assembled in that order is also the file you will need if anything must later be challenged.

II. Paying only once: treaty credit, S1 social-charge exemption and challenging the bill

A. Will HMRC tax the same sale and how does the France-UK treaty foreign tax credit work?

France taxes first, but Britain taxes its residents on worldwide gains, so the same sale can appear in two tax returns. The 2008 France-United Kingdom double tax convention, still in force, settles the conflict in two steps. First, it gives France the right to tax gains on the disposal of immovable property situated in France (2008 UK-France Double Taxation Convention, Article 13, GOV.UK). Your Dordogne cottage or Brittany flat is immovable property situated in France, so France may tax the gain and, as seen above, does so at the signing. Second, the treaty obliges Britain to relieve the double charge by credit: French tax paid on the same French-source gain is allowed as a credit against the British tax computed on that gain (same Convention, Article 24, GOV.UK). The treaty adds that gains of a British resident which France may tax under its other articles are deemed to arise from French sources (same Article 24), which is the bridge that lets HMRC recognise your French gain as French-source and credit the French tax.

In practice the credit works like this. You declare the sale in France through the 2048-IMM at completion, pay the French levy and social charges, and keep the assessment notices (avis d’imposition). You then declare the same disposal on your British Self Assessment return as a foreign gain, compute the British capital gains tax on it under British rules (different acquisition-cost rules, different reliefs, different annual exempt amount), and claim foreign tax credit relief for the French tax computed on the same gain, within the limit of the British tax on that gain. If the French tax is higher than the British tax on the same profit, the excess is not refunded by HMRC; if it is lower, you pay HMRC the difference. Timing matters because the two systems run on different clocks: France collects at the signing, while Britain taxes by tax year and return deadline, so keep a single schedule showing the euro gain, the exchange rate used, the French tax voucher and the sterling figures. Where the two administrations disagree about who may tax or about the amount of the credit, the treaty provides a mutual agreement procedure between the competent authorities (Article 26 of the Convention), which your adviser can invoke after domestic remedies.

Three British errors return again and again. The first is believing that paying in France ends the matter and omitting the British return: HMRC charges interest and penalties for an undeclared foreign disposal even when no extra tax is finally due. The second is claiming credit for the whole French debit including charges that Britain does not treat as creditable income tax; only the French tax on the same gain, computed in accordance with the treaty, qualifies, so the computation must separate income-tax levy, social levies and any additional taxes line by line. The third is converting currencies inconsistently: use one consistent published rate and the same gain definition on both sides, and attach the French notices to the British claim. Readers in the mirror situation, living in France and selling a house in Britain, face the same two-return exercise in reverse and will find the treaty credit logic explained from the other side in our guide to British residents in France selling a UK house. Get the French assessment right first, because every later credit depends on it.

B. Can your S1 cut the French social charges and how do you challenge an excessive assessment?

Alongside the income-tax levy, France bills social levies (prélèvements sociaux) on the same net gain: the CSG (contribution sociale généralisée, the general social contribution), the CRDS (contribution au remboursement de la dette sociale, the contribution repaying the social debt) and the solidarity levy. The base rule sits in the Social Security Code: “Les personnes physiques fiscalement domiciliées en France au sens de l’article 4 B du code général des impôts sont assujetties à une contribution sur les revenus du patrimoine assise sur le montant net retenu pour l’établissement de l’impôt sur le revenu” (Code de la sécurité sociale, art. L. 136-6, Légifrance), and that contribution expressly reaches “Des plus-values, gains en capital et profits soumis à l’impôt sur le revenu” (same article). For non-residents the social levies are collected together with the 244 bis A levy on the 2048-IMM, which is why the completion statement can look so heavy: two fiscal layers on one gain.

This is where the S1 can save a British vendor real money. The S1 is the portable document by which Britain, as the State paying your pension or covering your healthcare, certifies that you are insured under its system while you live in France; with it you join the French health system without paying twice. European coordination rests on a single-legislation principle: a person is subject to only one social-security system at a time. The Cour de cassation restated it in a September 2025 decision in these terms: the coordination regulations “consacrent le principe d’unicité de la législation de sécurité sociale, selon lequel la personne à laquelle les règlements s’appliquent n’est soumise qu’à la législation d’un seul État membre, en sorte que celle-ci, affiliée à un régime de sécurité sociale d’un État membre, ne doit pas contribuer au régime de sécurité sociale d’un autre État membre” (Cass., 2nd Civil Chamber, 25 Sept. 2025, No. 22-24.634). Applied to property gains, that principle produced the famous de Ruyter line of cases: levies that finance French social security and give no benefit in return cannot be imposed on someone insured in another European State. For a British vendor holding an S1, the CSG and CRDS elements of the French bill on the sale are therefore open to an exemption or refund claim, while the solidarity levy, which does not finance contributory social security in the same way, is treated differently and generally remains due. The distinction is technical, the saving is large, and the notaire will by default collect everything: the exemption works by claim, with the S1, the British National Insurance certificate and proof of cover attached, and any overpaid amount is recovered afterwards with interest where due.

If the bill remains excessive after those corrections, French law offers a ladder of remedies, and the Réunion case above shows it in action: the taxpayer first asked the administrative court (tribunal administratif) to pronounce “la décharge”, meaning full discharge, of the extra income-tax and social-charge assessments on his 2012 property gain, then the case travelled to the administrative court of appeal and to the Conseil d’État. Your own route depends on the paper you attack. Against the French assessment, file a formal claim (réclamation contentieuse) to the tax office, asking for discharge or reduction, setting out the correct acquisition price, the correct taper years, the treaty article and the S1 exemption, and enclosing the deeds, invoices, S1 and computation. If the administration rejects expressly or by silence, appeal to the administrative court within the time limit stated on the rejection, and keep paying or securing the disputed sum as the recovery rules require so that surcharges do not pile up during the dispute. Against an error by the notaire in the 2048-IMM itself, write to the notaire first with the corrected computation and ask for a rectifying filing; professional liability remains behind that. On the British side, amend the Self Assessment return or appeal the HMRC assessment within the statutory window, and use the treaty’s mutual agreement procedure where France and Britain each claim the larger slice. In every forum, the winning files share the same qualities: the acquisition deed, dated works invoices from registered businesses, proof of years of ownership, the S1 and insurance certificates, both tax assessments, and a single bilingual computation table both administrations can follow without translation.

Conclusion

Selling a French holiday home from Britain after Brexit is a two-country operation with one safe order: establish the French gain correctly, pay France first through the notaire, relieve Britain by treaty credit, and reclaim whatever the S1 takes off the social levies. Check the subtraction of price minus price, count the taper years under the scale of the year of sale, confirm the levy rate and the tax representative for sales above one hundred and fifty thousand euros, declare in both countries, and challenge in writing wherever a line is wrong. The figures feel final on completion day, but the Réunion and social-levy cases prove that a careful file can reopen them. Prepared before the compromis, your sale completes once; prepared after, it completes twice, once at the signing and once in correspondence.

Need a quick opinion on your case?

Our firm advises British vendors selling French property. Telephone consultation within 48 hours with an avocat of the firm: +33 6 46 60 58 22. You can also reach us through our contact page. Maître Reda Kohen, avocat au Barreau de Paris.