You have settled in France, but you still own the old family home in Manchester, Bristol or Bromley. The estate agent has found a buyer, the conveyancer in England is asking for completion dates, and a worrying question lands on your desk: if I sell my British house while living in France, will both countries tax the gain, and how do I avoid paying twice? Since Brexit, the answer has hardened. As a French tax resident you are taxable in France on your worldwide gains, the United Kingdom still taxes the disposal because the land sits on its soil, and the France-UK double tax treaty decides who gives way and how. On top of that, two clocks start running at once: the British 60-day capital gains return and the French annual tax return the following spring. Miss one of them and you face penalties on one side of the Channel and a lost treaty credit on the other. This guide explains, step by step, which country taxes what, how the French bill is calculated on a UK sale, how the treaty credit works in practice, and how to challenge an assessment that gets the residence date, the holding period or the foreign tax credit wrong.
I. Selling Your UK Home as a French Tax Resident After Brexit: Which Country Taxes the Gain?
A. France taxes your worldwide gains once you are French tax-resident: how residence is fixed and proved
The starting point is blunt. French law provides that “Les personnes qui ont en France leur domicile fiscal sont passibles de l’impôt sur le revenu en raison de l’ensemble de leurs revenus.” In plain English: once France regards you as fiscally domiciled on its territory, you owe French income tax on all of your income and gains, wherever in the world they arise. A gain realised on a house in Leeds or Lewisham is therefore inside the French tax net from the moment you are French-resident, even though the property itself has never moved. The legal anchor is article 4 A of the Code général des impôts (the French Tax Code), and it applies to British newcomers exactly as it applies to French nationals.
Whether you are French tax-resident depends on three alternative tests set out in article 4 B of the same Code. The statute states: “1. 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 ; b. Celles qui exercent en France une activité professionnelle, salariée ou non, à moins qu’elles ne justifient que cette activité y est exercée à titre accessoire”. A third test, at c. of the same article, covers persons who have the centre of their economic interests in France. Meeting any single one of these tests is enough: the family home (foyer, meaning the place where your family habitually lives), the main place of stay (séjour principal, generally where you spend most nights of the year), professional activity, or the centre of economic interests. For a British family that has rented or bought in Lyon, enrolled the children at the local collège and spends ten months a year there, the foyer test is met even if one spouse still commutes to London.
Two practical consequences follow. First, keep and organise your residence evidence from day one: the long-stay visa or Withdrawal Agreement residence permit (titre de séjour, the French residence card), the lease or acte de vente (the notarised deed of purchase), electricity and taxe d’habitation bills, school certificates, French health cover, and travel records showing nights spent in each country. If the French tax office (service des impôts des particuliers) ever queries your residence starting date, that file decides whether a given sale falls inside or outside French taxation. Readers who live between the two countries will find a detailed method in our guide to proving tax residence between France and the UK after Brexit.
Second, dual residence is possible: London may still regard you as UK-resident under its own Statutory Residence Test while Paris regards you as French-resident under article 4 B. That overlap does not create double taxation by itself, because the France-UK treaty contains tie-breaker rules that attribute residence to one state for treaty purposes. But it does mean paperwork in both countries, and it means you should never assume that leaving the UK, or keeping a British address for post, settles the question. Pin down your residence date precisely, because every calculation that follows, from the applicable rate to the treaty credit, turns on it.
B. The United Kingdom still taxes the sale because the land is British: treaty situs rule, French credit, and the two simultaneous deadlines
The mirror principle is that land is taxed where it lies. Under the France-UK double tax treaty, gains from immovable property situated in one state may be taxed by that state even when the seller lives in the other. The treaty’s official commentary, published by the French tax administration, confirms the architecture: The treaty signed in London on 19 June 2008 between France and the United Kingdom covers both income tax and tax on capital gains. That is the France-UK treaty of 19 June 2008, still fully in force after Brexit, and it is the document that prevents the same pounds of gain being taxed twice in full.
Concretely, the treaty gives the United Kingdom the first right to tax the disposal of your English or Welsh house, and it obliges France, as your state of residence, to eliminate the resulting double taxation. The administration’s commentary on capital gains explains the mechanism: gains of a French resident that the United Kingdom may tax under the treaty’s property-gains provisions include gains from disposing of immovable property situated in the UK, and the treaty then requires the state taxing only under the residual provision to eliminate double taxation as if the gains came from sources in the other state. In practice, you compute and pay the British tax first, then you declare the same gain in France and France grants a credit against the French tax attributable to that gain. The full treaty analysis is published in the official commentary on the treaty’s capital-gains articles. The essential point for a seller is that the credit is capped: France refunds the British tax only up to the amount of French tax due on the same gain, so any excess of British tax over French tax stays definitively yours to bear, and any shortfall remains payable in France.
This two-stage system creates two deadlines that run in parallel and must both be honoured. On the British side, the seller must use the UK capital gains property account: HMRC guidance requires any CGT due on UK residential property to be reported and paid within 60 days of completion, with interest and penalties for late filing, as stated on the official gov.uk guidance for UK property sales. That 60-day return applies whether you are UK-resident or not, so a British national living in Bordeaux who completes on a Sheffield sale on 15 October must have reported and paid the British estimate by mid-December. On the French side, the same gain is declared on your French income tax return the following spring through your personal account on impots.gouv.fr, with the foreign-source gain identified so that the treaty credit can be applied. Landlords who already declare British rents in France will recognise the logic, described in our guide to declaring UK rental income as a French resident, but a sale is a one-shot event with no room for a corrective return the year after, which is why the file must be right first time.
A final warning for this section concerns private residence relief. If the house you are selling was your main home for part of the ownership period, both systems may grant partial relief for the years of occupation, but the rules, the exempt periods and the evidence required are not identical on the two sides of the Channel. Do not assume that full exemption in one country means full exemption in the other. Compute each liability under its own rules, keep the HMRC computation and the proof of payment, and carry both into the French declaration so the credit can be checked euro by euro.
II. French CGT on the UK Sale: How the Bill Is Built, Declared and Challenged
A. How the French bill is built on a British sale: charge, 19 per cent rate, holding-period relief, surtax, and the Brexit rate trap for those who already left
For a French tax resident, the charge on the UK sale follows the ordinary French regime for real-estate gains. The Code provides that “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”, under article 150 U of the Code général des impôts. A sale for consideration (cession à titre onéreux, meaning any sale as opposed to a gift or inheritance) of a built or unbuilt property therefore triggers French capital gains tax (plus-value immobilière, literally the increase in the property’s value), and a house in England is no exception once the seller is French-resident.
The rate structure has two layers. The income-tax layer is a flat 19 per cent rate for individuals domiciled in France, as the administration confirms in the official computation guidance for article 150 U gains, which also confirms that article 150 U gains bear both the flat-rate income tax and the social levies. The second layer is the social levies (prélèvements sociaux, the French social charges on capital income, currently totalling 17.2 per cent), so the combined headline burden on the taxable gain is of the order of 36.2 per cent before any relief, plus a possible additional surtax on large gains. That surtax exists by statute: “Il est institué une taxe sur les plus-values réalisées dans les conditions prévues aux articles 150 U et 150 UB à 150 UD”, under article 1609 nonies G of the Code général des impôts, and it must be factored into any sale where the net taxable gain exceeds the statutory threshold.
Both layers are then reduced by holding-period relief (abattement pour durée de détention, a statutory percentage reduction that grows with each year of ownership), but on different timetables, and this is where many British sellers overpay. The administration’s scale grants, for income tax, relief of 6 per cent for each year of ownership beyond the fifth up to the twenty-first, plus 4 per cent for the twenty-second year, so that full income-tax exemption is reached after twenty-two years of ownership. For the social levies the relief runs slower, at 1.65 per cent per year beyond the fifth up to the twenty-first, 1.60 per cent for the twenty-second year, and 9 per cent per year thereafter. Both scales are published in the official guidance on computing the taxable gain. Take a concrete illustration. A couple bought a flat in Leeds in 2011 and sells it in 2026 after fifteen years of ownership. For income tax, ten qualifying years at 6 per cent erase 60 per cent of the gain, leaving 40 per cent taxable at 19 per cent. For social levies, ten years at 1.65 per cent erase only 16.5 per cent, leaving 83.5 per cent taxable. The same sale therefore produces two very different taxable bases, and any assessment that applies one scale to both layers is wrong on its face.
The starting figure to which those scales apply is the net gain: sale price minus the justified acquisition cost, converted into euros. Build this figure with the same rigour as a French notaire (the French public officer who authenticates conveyances) would. Keep the English purchase deed and completion statement, the acquisition costs (stamp duty, conveyancer and agent fees on purchase), invoices for improvement works carried out by contractors (travaux d’amélioration, meaning works that add lasting value, as opposed to mere repairs), and the sale deed with the selling-agent commission. Convert each amount at the exchange rate of its own date and keep the rate source, because a gain computed in sterling then translated once at the sale date can differ materially from a gain computed euro by euro. If works invoices are missing, ask your adviser before the declaration whether the statutory flat-rate uplift for works can be used in your case rather than inventing figures the administration will reject.
One Brexit trap deserves its own paragraph, because it now decides the rate for every British seller who has already left France. When the seller is no longer French-resident at the date of sale, the gain on French property falls under a separate flat-rate levy whose rate varies with the seller’s status and state of residence, as the official guidance on the non-resident levy states. Before Brexit, a British seller living in London paid the reduced European rate; since the United Kingdom became a third country, the higher third-country rate applies. The courts have policed exactly this kind of rate gap. In a leading case, the Conseil d’État (France’s supreme administrative court) recorded that “la cession par M. B…, ressortissant suisse résidant à Monaco, le 20 mars 2012, d’un ensemble immobilier situé à Nice lui a permis de réaliser une plus-value immobilière assujettie au prélèvement prévu par l’article 244 bis A du code général des impôts au taux de 33,1/3 %”, before examining the partial relief granted down to the 19 per cent European rate: Conseil d’État, 9th chamber, 23 June 2022, No 445785. The statutory basis of that levy opens with the words “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”, under article 244 bis A of the Code général des impôts. The lesson for a British owner is direct: if you sell a French second home after returning to live in Britain, expect the third-country rate, and check the former-main-home exemption immediately, because it is fenced by a short deadline. The statute grants it only on a double condition, recalled by the Conseil d’État: “Cette exonération s’applique à la double condition que la cession soit réalisée au plus tard le 31 décembre de l’année suivant celle du transfert par le cédant de son domicile fiscal hors de France et que l’immeuble n’ait pas été mis à la disposition de tiers, à titre gratuit ou onéreux, entre ce transfert et la cession” (Conseil d’État, 9th-10th chambers combined, 10 December 2021, No 456728). Sell in the year after departure without letting the property in the meantime, or lose the exemption entirely.
B. Declaring correctly and challenging the bill: documents, credit proof, complaint and court appeal
Declaration is where the treaty credit is won or lost, so treat the French return as the second half of the conveyancing file. Declare the gross gain, the deductible costs, the holding period with its start and end dates, and the British tax paid with the HMRC computation and the bank proof of payment attached or held ready for the first request. Claim the credit expressly against the French tax on the same gain, and reconcile the two computations line by line: the British gain in sterling and the French gain in euros will legitimately differ because costs, reliefs and exchange-rate dates differ, but the administration will only credit British tax that genuinely relates to the gain France is taxing. Families holding British assets through trusts should also review disclosure, on which our guide to declaring a UK trust as a French resident gives the method, since an undisclosed structure behind the sold property can turn a routine return into a penalty case.
When the assessment (avis d’imposition, the tax bill, or the mise en recouvrement, the formal collection notice) arrives and looks wrong, work through a fixed checklist before writing anything. First, the residence date: if the sale completed before you became French-resident, France had no worldwide claim at all, and the file should show the arrival evidence. Second, the treaty credit: verify that the British payment was actually credited and capped correctly, and that private-residence relief granted in London was not mistakenly treated as wiping out the French gain. Third, the holding period: recount the full years of ownership from the acquisition deed to the sale deed, and check that the income-tax scale and the slower social-levies scale were not confused. Fourth, the costs: every rejected invoice or missing proof inflates the gain, so resubmit the complete set with translations where needed. Fifth, the currency: confirm the gain was computed from euro-denominated figures rather than a single sterling subtraction converted once. Sixth, the surtax: confirm it was applied, if at all, to the correct base and threshold. Seventh, for sellers who had already left France, the former-main-home deadline and the no-letting condition described above. Most successful challenges are won on one of these seven points, not on broad arguments about fairness.
The remedy route is then strictly ordered. Start with the formal complaint to the tax administration (réclamation contentieuse, the written claim asking the administration to discharge or reduce the tax). The Code provides that “Les réclamations relatives aux impôts, contributions, droits, taxes, redevances, soultes et pénalités de toute nature, établis ou recouvrés par les agents de l’administration, relèvent de la juridiction contentieuse lorsqu’elles tendent à obtenir soit la réparation d’erreurs commises dans l’assiette ou le calcul des impositions, soit le bénéfice d’un droit résultant d’une disposition législative ou réglementaire”, under article L 190 of the Livre des procédures fiscales (the French Tax Procedure Code). In income-tax matters the complaint must as a rule be filed by 31 December of the second year following the year of the assessment, so a 2026 assessment is normally challenged by the end of 2028, and the complaint must state precisely which of the seven errors above is invoked, with the supporting documents attached. Keep the proof of filing and diary the reply: an express rejection, or silence kept beyond the statutory period, opens the door to the court.
The court stage belongs to the administrative court (tribunal administratif, the first-instance court for tax disputes), and its time limit is short and strict: “La juridiction ne peut être saisie que par voie de recours formé contre une décision, et ce, dans les deux mois à partir de la notification ou de la publication de la décision attaquée”, under article R 421-1 of the Code de justice administrative (the Administrative Justice Code). The application must target the rejection decision, repeat the exact figures of the corrected computation, and attach the HMRC documents, the deeds, the invoices and the exchange-rate evidence in an ordered bundle. Meanwhile, remember that the administration’s own right to audit is itself time-limited: “Pour l’impôt sur le revenu et l’impôt sur les sociétés, le droit de reprise de l’administration des impôts s’exerce jusqu’à la fin de la troisième année qui suit celle au titre de laquelle l’imposition est due”, under article L 169 of the Livre des procédures fiscales. Keep the whole sale file for at least that period, and longer if any complaint or court case is pending, because the file you can produce is the ceiling of what you can recover.
Conclusion
A British resident of France who sells a UK home faces two taxes, two returns and two clocks, but only one economic gain. France taxes it as part of your worldwide income from the day you become French-resident, the United Kingdom taxes it because the bricks stand on British soil, and the 2008 treaty makes France credit the British tax against the French bill. File the British 60-day return on completion, declare the same gain on the French return the following spring with the HMRC proof attached, compute the French layers exactly at 19 per cent plus social levies with each holding-period scale applied to its own base, and check the surtax, the currency conversion and the credit cap before signing. If the assessment is wrong, challenge it in order: precise complaint to the administration, then the administrative court within two months of the rejection. Prepared this way, the sale of the old British home funds the French chapter of your life instead of funding two treasuries for the same gain.
Need a quick opinion on your case.
If you are about to sell your British home, or you have just received the French assessment on a UK sale, get advice before the next deadline passes. Our firm offers a telephone consultation within 48 hours with a lawyer of the firm to review your residence date, your gain computation, your treaty credit and your options for challenge. Call +33 6 46 60 58 22 (Maître Reda Kohen) or write to us through our contact page with a copy of your English deeds, your HMRC computation and the French notice.