You moved to France, you pay your French income tax every spring, and you kept the house you used to live in — in Manchester, Guildford, Edinburgh or Bristol. Now you have sold it, or you are about to, and two tax administrations want a share of the same gain. This is the single most expensive misunderstanding British residents in France face after Brexit: many assume that because the house stands in England and the sale was handled by an English conveyancer, the French tax office (the fisc) has nothing to do with it. The opposite is true. As a person whose tax home (domicile fiscal) is in France, you are taxed on your worldwide gains, including the sale of a British property, and the France–United Kingdom double tax treaty (convention fiscale) does not exempt the gain — it shares it out. The good news is that the treaty machinery works well when you operate it correctly: the United Kingdom taxes the gain first, France taxes it second, and France then wipes out the double charge with a tax credit (crédit d’impôt) equal to the British tax, capped at the French tax on the same gain. The bad news is that every step has its own form, its own deadline and its own calculation method, and a mistake on any one of them produces either penalties in London or a double bill in Paris. This guide walks through both sides in order: the British 60-day Capital Gains Tax return, the French worldwide declaration with its 19 per cent tax, surtax and 17.2 per cent social levies (prélèvements sociaux), the treaty credit with a worked example, and the remedies available when either bill is wrong.

I. The United Kingdom taxes the sale first and France taxes your worldwide gains

A. How the British 60-day Capital Gains Tax return works when you sell from France

Since April 2015, a person who is not resident in the United Kingdom has been within Capital Gains Tax on disposals of UK residential property, and since April 2019 the charge has covered commercial property and indirect disposals as well. Living in Lyon, Bordeaux or Paris therefore does not take you outside the British charge on your old house in Leeds. The treaty confirms this priority. Article 14, paragraph 1 of the France–United Kingdom convention of 19 June 2008 gives the state where the property stands the right to tax gains from selling immovable property there. In treaty language, that right to tax means the United Kingdom taxes first, and France, as your state of residence, deals with the double taxation second. The convention is still fully in force after Brexit; leaving the European Union changed your residence rights, not the tax treaty, and HM Revenue and Customs applies it exactly as before.

The British deadline is the sharpest in this whole process. The official guidance requires non-residents to report the disposal and pay any tax due within 60 days of completion, and warns that interest and penalties apply for late reporting or payment. Sixty days runs fast when you live abroad, post goes astray and you are waiting for final statements from the conveyancer, so diary the completion date the day contracts complete and start the online UK property return immediately. The return is filed through the HMRC online service for UK property disposals, even by non-residents, and payment on account is due with it; the gain is then finalised on your Self Assessment return if you file one. Penalties start with a fixed sum and grow with delay, with interest on late-paid tax, so a return filed on day 75 already costs money for nothing.

The British calculation starts from the sale price (proceeds) and subtracts the acquisition cost plus buying and selling expenses — estate agent fees, conveyancing, Stamp Duty Land Tax paid on purchase — plus the cost of improvements such as an extension or a new roof, but not routine repairs or decoration. Keep every invoice: HMRC can ask years later, and a loft conversion with no paperwork is worth nothing in the computation. Then come the reliefs, and this is where former residents often save the most. Private Residence Relief exempts the years you actually lived in the house as your main home, plus a final period of ownership even after you moved out — the exempt final period is currently 9 months, so check the figure in force for your year of sale. If you let the house after leaving, letting relief now applies only in narrow shared-occupancy cases, so most expatriate landlords get no letting relief at all. An annual exempt amount (a tax-free slice of gain each year) is deducted if available — verify the current amount on the official pages before you compute, because it has been reduced sharply in recent years. The balance is charged at the residential-property Capital Gains Tax rates, which are higher than the rates for other assets; confirm the rate band against your UK taxable income position for the year, including how the gain stacks on top of it. Where the house was jointly owned with a spouse or partner, each owner files and pays on their own share, and transfers between spouses or civil partners living together generally pass with neither gain nor loss, which can legitimately reshape the combined bill before sale. None of this is done for you by the conveyancer: unlike a French sale handled by a notaire, an English sale has no tax withheld at source, so the entire 60-day compliance rests on you.

B. Why France taxes the same sale and which French forms and rates apply

France taxes you because you live here. Article 4 A of the French General Tax Code (code général des impôts) states: “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 terms, French tax residents pay French tax on all their income and gains, wherever in the world they arise. Your tax home is in France if France is where your household is (your foyer, your family home) or where you spend most of your time (your lieu de séjour principal), or where you carry on your main professional activity — Article 4 B lists these tests, beginning: “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”. A British citizen retired in the Dordogne, an employee working in Paris, or a remote worker living full-time in France all meet these tests even while keeping a British passport. Moving into a French home does not need any registration to make you resident; the facts of daily life decide.

The painful consequence is that your English house does not qualify for the French main-home exemption. Article 150 U exempts only property “Qui constituent la résidence principale du cédant au jour de la cession” — the home that is your principal residence on the very day of sale. A house in Sheffield while you live in Toulouse fails that test by definition, however many years you lived there before emigrating. Nor does the one-off re-employment exemption help most sellers: it requires you not to have owned your main home during the four years before the sale and to plough the price back into a French main home within 24 months. So the gain on the British house is, in principle, fully taxable in France, and the specific non-resident levy of Article 244 bis A — which provides that, “Sous réserve des conventions internationales”, gains realised by non-residents on French property “sont soumises à un prélèvement” — does not apply to you at all: you are a French resident selling foreign property, taxed under the ordinary resident rules, not a non-resident selling French property.

French compliance has two stages, and missing the first is the classic expatriate error. Within one month of the sale, you must file a capital-gains return (déclaration de plus-value) with your local tax office (service des impôts des particuliers): the official guidance for property outside mainland France requires form 2048-IMM to be filed with your local tax office within one month of selling a building abroad. Because there is no French notaire in an English conveyance to file and pay for you, you — or your French tax adviser — prepare form 2048-IMM personally, computing the French-law gain and paying the tax shown. Then, the following spring, the same gain is reported again on your annual French income tax return: the foreign gain goes on the foreign-income schedule (formulaire 2047, revenus de source étrangère) and flows into the main return (2042-C) (Article 170 requires the annual declaration of worldwide income), where the treaty tax credit is claimed. Skipping the 2048-IMM because it will all be on next year’s return, or so taxpayers assume, triggers late-payment interest and penalties; skipping the 2047 because the 2048 supposedly already dealt with it forfeits or scrambles the treaty credit. Do both.

The French calculation differs from the British one, so expect two different taxable amounts. The sale price is converted into euros at the exchange rate on the sale date, and the acquisition price likewise at its own historic rate — currency movements over a decade of ownership can add or remove thousands of euros of taxable gain, which surprises sellers who think in pounds. Deductible costs follow French rules: acquisition expenses at their real amount or a 7.5 per cent flat rate if you hold the title deed evidence the administration requires, improvement works proved by invoices from proper businesses (do-it-yourself materials without labour invoices count poorly), and selling costs. Then comes the holding-period allowance (abattement pour durée de détention), which is the single biggest reducer of French bills: for income tax, 6 per cent per year from the 6th to the 21st year and 4 per cent for the 22nd year, giving total exemption from income tax after 22 years of ownership; for social levies, 1.65 per cent per year from the 6th to the 21st year and 1.6 per cent for the 22nd year onward, giving total exemption after 30 years. The official service-public page summarises the principle: property held long enough escapes tax entirely, with income tax gone first and social levies later. On the reduced gain, income tax applies at a flat 19 per cent — “The capital gain on real estate, after deduction of the allowance(s), is taxed at the rate of 19% after allowances, as confirmed on service-public.fr. Large gains attract an additional surtax (surtaxe sur les plus-values élevées) under Article 1609 nonies G once the taxable gain exceeds 50,000 euros, at rates rising from 2 to 6 per cent. Finally, social levies apply at 17.2 per cent (Article L136-6 of the Social Security Code), at the 17.2 per cent rate confirmed on the same official page. Readers who also let their British house should note the parallel treatment of rents, where France likewise taxes worldwide rental income before granting a treaty credit, as explained in our guide to how France taxes UK rental income and computes the treaty credit.

II. How the treaty wipes out the double tax and how to challenge a wrong bill

A. What credit France must give for the British tax, with a worked example

The elimination mechanism sits in Article 24 of the 2008 convention. For gains on immovable property covered by Article 14, paragraphs 1 and 2, France grants a credit equal to the British tax actually paid, capped at the amount of French tax on the same gain. Two companion rules complete the picture: paragraph 4(b) assigns the duty of eliminating double taxation to the residence state rather than the taxing state, which designates France as the state that must act; and paragraph 5 confirms the article covers both income and capital gains, so the whole machinery plainly covers your house sale. The French tax administration describes the same result in its own guidance on foreign disposals: a treaty-based credit deductible from French tax, equal to the French tax computed on the gain or to the foreign tax paid, capped at the French tax. In practice, whichever is smaller — the British tax you actually paid or the French tax computed on the gain — is subtracted from your French bill, and any excess British tax is simply lost: the credit never produces a refund.

The highest French court for tax matters has clarified how generously this credit applies. In its opinion of 12 February 2020 on the Franco-British convention (Conseil d’État, avis n° 435907, ECLI:FR:CECHR:2020:435907.20200212, full text on Légifrance), the court held that the treaty’s opening phrase “notwithstanding any other provision of this Convention” means the gain is taken into account for French tax even where the treaty gives the United Kingdom a taxing right, and — decisively for taxpayers — that the condition of being subject to United Kingdom tax “n’exige pas que les revenus en cause aient été soumis à une imposition effective”, meaning it does not require the income to have been effectively taxed. Concretely, a gain that falls inside the British tax base opens the French credit even if allowances or reliefs reduced the British tax actually payable to a small amount or to nothing; what matters is inclusion in the British base, proved by your British return, not the size of the cheque sent to HMRC. Keep the British computation, the 60-day return receipt and proof of payment with your French file: they are the documentary keys to the credit.

A worked illustration shows how the pieces fit. Suppose you bought a flat in Bristol in 2014 for 200,000 pounds (about 245,000 euros at the time) and sell it in 2026 for 320,000 pounds (about 375,000 euros at the sale-date rate), after 12 years of ownership, having lived in France throughout the letting period. The euro-denominated gain before costs is roughly 130,000 euros. Deduct selling costs and evidenced improvements — say 15,000 euros — leaving 115,000 euros. The holding allowance for 12 years gives 42 per cent off for income tax (7 years at 6 per cent) and about 11.55 per cent off for social levies (7 years at 1.65 per cent): around 66,700 euros taxable for income tax and 101,700 euros for social levies. Income tax at 19 per cent is about 12,670 euros, the surtax on the portion above 50,000 euros adds roughly 1,000 euros, and social levies at 17.2 per cent add about 17,500 euros — a total French bill near 31,000 euros before the credit. If the British Capital Gains Tax actually paid was, say, 14,000 pounds (about 16,500 euros), that full amount is credited because it sits below the French tax on the same gain, leaving about 14,500 euros payable in France. If instead the British tax had been 35,000 euros — higher than the French tax — the credit would be capped at the French figure and the French balance would be zero, with the excess unrecoverable. Figures are rounded and every file differs on costs, rates of exchange and reliefs, but the structure never changes: compute each side under its own rules, pay Britain first, credit against France second.

The errors that destroy this mechanism are depressingly repetitive. First, deducting the British tax from the gain as if it were a cost, instead of claiming it as a credit against the French tax — the treaty grants a credit (imputation), not a deduction, and a deduction wastes most of its value. Second, omitting the foreign-income schedule 2047, which is the document on which the credit is computed; without it, the computer sends a bill for the full French tax. Third, declaring the gain in the wrong year: France taxes the year of the legal transfer, and a completion straddling 31 December must be allocated correctly. Fourth, forgetting the surtaxe above 50,000 euros of taxable gain, which the 2048-IMM computes but a hand-rolled return may miss. Fifth, assuming Brexit ended all this: the 2008 convention is bilateral, independent of EU membership, and fully in force. And sixth, converting pounds at the wrong rate or the wrong date — use the sale-date rate consistently for proceeds and the historic rate for acquisition, and keep both sources.

B. How to challenge the British penalties and the French bill when either is wrong

Start on the British side, because its clock runs fastest. If the 60-day return was late, interest runs automatically but penalties can be appealed where you have a reasonable excuse in law — serious illness, a bereavement, a conveyancing failure that left you without the figures, or reliance on advice that proved wrong can qualify, while simply not knowing the rule almost never does. Read the penalty notice itself: it states the appeal route and the 30-day appeal window, and appeals are made to HMRC with evidence attached. If the computation itself is wrong — a missed improvement cost, Private Residence Relief omitted for the years you lived there, the final exempt months forgotten — an filed return can generally be amended within the statutory amendment window, so correct first and argue second. Where HMRC has opened an enquiry, reply fully and on time; silence converts a correctable computation dispute into an assessed bill with penalties on top. Keep a complete file: completion statement, acquisition deeds, improvement invoices, correspondence with the conveyancer, and the payment reference for the tax paid — the same papers prove the French credit, so one well-kept file serves both administrations.

On the French side, every challenge begins with a prior complaint to the tax administration (réclamation préalable), and it is compulsory before any court action. The Livre des procédures fiscales provides (Article R190-1): “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.” Send it to the tax office that issued the notice (your local service des impôts des particuliers if you live in Paris or elsewhere in Île-de-France), by secure message through your impots.gouv.fr personal account so the date is stamped, setting out the facts, the computation you defend and every exhibit: British return, proof of payment, exchange-rate sources, invoices. Mind the guillotine deadline in Article R196-1: claims must reach the administration “au plus tard le 31 décembre de la deuxième année suivant celle” of the collection notice or of the payment where no notice was issued — in practice, about two years, but check the date printed on your own notice and never assume. If the administration rejects the claim expressly or lets six months pass without answering (an implied rejection), you may take the dispute to the administrative court (tribunal administratif) of your domicile — for Paris residents, the tribunal administratif de Paris — within two months. Ask the court, as appropriate, for discharge of the double charge, correct computation of the Article 24 credit with interest on late refunds, and, where the administration’s position was untenable, costs.

Two cross-border safety nets deserve to be known before positions harden. The treaty’s mutual agreement procedure (Article 26) lets you present your case to the competent authority — as a French resident, the French tax administration — where you consider that the actions of one or both states tax you contrary to the convention, regardless of domestic remedies and within three years of the first notification or six years from the end of the tax year concerned. The competent authority is that of your residence state, reachable through the 2008 convention procedure. This runs alongside, not instead of, domestic appeals, and it is the proper channel where both states each claim the gain was misallocated. And within France, the formal rescrit (ruling request) procedure lets you put a doubtful point — residence, allowance, credit computation — to the administration before you file, securing a written answer you can rely on. Whichever route you take, act in this order: secure the British position and its paperwork first, file the French 2048-IMM and 2047 correctly, claim the credit, and only then litigate what remains. Most double bills this practice sees are not points of high treaty principle but unclaimed credits, unfiled schedules and missed deadlines — all curable if caught inside the time limits, all fatal outside them.

Conclusion

Selling your English house from France after Brexit means paying tax in two countries on one gain, once in the right order. The United Kingdom taxes the disposal first under its non-resident charge and its treaty right over immovable property, and you must report and pay within 60 days of completion or face interest and penalties. France taxes second, because French residents are liable on worldwide gains: file form 2048-IMM within a month of the sale, report the gain again on forms 2047 and 2042-C the following spring, compute under French rules with the holding-period allowances, 19 per cent tax, the surtax above 50,000 euros and 17.2 per cent social levies. The France–United Kingdom convention of 19 June 2008 then eliminates the double charge through a credit equal to the British tax paid, capped at the French tax on the same gain — a mechanism the Conseil d’État has confirmed applies even where British reliefs reduced the tax effectively paid. Keep one complete file serving both sides: British completion paperwork, improvement invoices, the 60-day return and payment proof, exchange-rate evidence, and the French returns. And when a bill ignores the credit, misstates the gain or penalises a compliant seller, challenge it in the right forum inside the time limit: HMRC appeal for British penalties, prior complaint then administrative court in France, and the treaty’s mutual agreement procedure where both states are at fault. Handled in that order, the sale closes cleanly and the same gain is never taxed twice.