You are British, you own a house in France — perhaps a Dordogne farmhouse bought years ago, a Paris flat, or shares in the family société civile immobilière (SCI, the French non-trading property company many British families use to hold a holiday home) — and an unfamiliar brown envelope or a message in your online tax account tells you that you owe the impôt sur la fortune immobilière (IFI, the French annual tax on net real-estate wealth). The figure can be shocking: several thousand euros on top of your taxe foncière (the local land-and-buildings tax paid by owners) and, for a second home, the taxe d’habitation sur les résidences secondaires (the occupancy tax still charged on second homes). Many British owners assume this must be a mistake, or that Brexit changed something. In most cases it is neither: since 1 January 2018 the IFI has taxed the net value of real-estate wealth above 1,300,000 euros, whether you live in France or simply own French property from across the Channel, and neither Brexit nor the France–United Kingdom double tax convention removes that charge on French land and buildings.

This guide explains, for a British reader, exactly how the IFI works after Brexit: who is liable and on which property, how the French tax office values your houses and your SCI shares, which debts you may deduct, how the bill is calculated and declared, and — the practical part most guides skip — how you challenge an assessment that overvalues your home, counts property it should not count, or taxes you on a residence basis that does not fit your situation. French legal terms are explained at first use, and every decisive legal proposition is linked to its official source: the Code général des impôts (CGI, the French tax code) on Légifrance, the Livre des procédures fiscales (LPF, the tax procedure code), published decisions of the Cour de cassation (France’s supreme court for civil and criminal matters), and the official service-public.fr guidance pages. If you also received a second-home occupancy tax bill, our companion guide on challenging an incorrect taxe d’habitation assessment covers that separate tax; if your preliminary question is where you are tax resident at all, start with our guide on proving tax residence between France and the UK.

I. Do you actually owe French IFI wealth tax after Brexit: residence, threshold and property counted

A. Are you taxable in France at all — and on your worldwide houses or only your French ones?

The starting point is article 964 of the CGI, which creates the tax in these terms: a yearly tax on real-estate assets applies where “lorsque la valeur de leurs actifs mentionnés à l’article 965 est supérieure à 1 300 000 €” — that is, when the value of the assets described in article 965 exceeds 1,300,000 euros. Below that net figure you owe nothing and, as will be seen, you file nothing under the IFI head. Above it, the same article draws the decisive distinction for British readers between two positions. First, individuals whose domicile fiscal (tax home, the French concept of tax residence) is in France are taxable on the relevant assets “situés en France ou hors de France” — situated in France or outside France, meaning worldwide. If you moved to France permanently, took up your main home there and became French tax resident, your cottage in Kent or your flat in Edinburgh counts alongside your French house once your total worldwide net property wealth passes the threshold. Your UK property is not exempt from French IFI merely because it stands in Britain.

Secondly, individuals who are not French tax resident are taxable only on a narrower base: French-situated immovable property and rights, plus shares in companies and bodies representing French real estate. If you live full-time in the United Kingdom and keep a holiday house in the Luberon, only your French property wealth is examined — your British home and any non-French investments are outside the IFI. This is why the residence question must be settled first: a British couple splitting the year between London and France, or a retiree unsure whether the move is permanent, can face a bill computed on the wrong base in either direction. The tax office sometimes treats a returning expatriate as worldwide-liable too early, or treats a genuine French resident’s UK buy-to-let portfolio as invisible when it should be declared. Our detailed residence guide linked above walks through the evidence the administration actually examines.

One relief softens the landing for newcomers, and it matters enormously to British families relocating after Brexit. Under the same article 964, individuals who “n’ont pas été fiscalement domiciliées en France au cours des cinq années civiles précédant celle au cours de laquelle elles ont leur domicile fiscal en France ne sont imposables qu’à raison des actifs mentionnés au 2°” — those who were not French tax resident during the five calendar years before establishing their French tax home are taxable only on the narrow, French-assets base. That shelter runs, for each year the taxpayer keeps a French tax home, “jusqu’au 31 décembre de la cinquième année qui suit celle au cours de laquelle le domicile fiscal a été établi en France” — until 31 December of the fifth year after the tax home was established in France. Concretely, a British family that moves to Lyon in 2026 after at least five years outside the French tax net is taxed for five years only on French property, even though it is French tax resident; a UK rental portfolio or a Spanish apartment stays out of the IFI until the sixth year. After that period, worldwide liability applies in full. Claiming this shelter requires proving the five prior years of non-residence, so keep old UK tax returns, P60s, council tax bills and travel records.

Two cross-border points complete the picture. First, the France–United Kingdom double tax convention (signed 19 June 2008, in force, with its official English text published by HM Revenue & Customs — see the France tax treaties page on gov.uk) allocates the right to tax immovable property to the country where it stands. France therefore keeps the right to levy IFI on French houses whoever owns them, and the United Kingdom cannot be asked to absorb the charge. Secondly, and symmetrically, there is no British tax credit to claim against the IFI, because the United Kingdom levies no equivalent annual wealth tax: double-tax relief through a foreign tax credit works for income and gains, not for a French-only wealth tax. The practical consequence is blunt but important — an IFI bill on a French house cannot be neutralised in London; it must be checked, reduced where the law allows, or challenged in France. Exchange-rate movements add a final trap for the unwary: a worldwide-liable British resident values UK property in euros at 1 January, so a weak pound can quietly pull a portfolio under the threshold while a strong pound pushes it over, with no change in bricks and mortar.

B. Which of your houses, shares and rights actually count — and which loans come off?

The taxable base is defined by article 965 of the CGI: “L’assiette de l’impôt sur la fortune immobilière est constituée par la valeur nette au 1er janvier de l’année” — the base consists of the net value at 1 January of the year. Two baskets then feed that base. The first covers all immovable property and rights belonging to the taxpayer — and to the taxpayer’s minor children where the taxpayer has administration légale (legal administration of the child’s assets) — which catches houses, flats, building land, and rights such as usufruit (usufruct, the lifelong or fixed-term right to use another’s property and take its income) and bare ownership interests. The second basket covers shares in companies and bodies, French or foreign, but only “à hauteur de la fraction de leur valeur représentative de biens ou droits immobiliers” — up to the fraction of their value representing directly or indirectly held taxable real estate. For a British family holding a Provençal villa through an SCI, this is the provision that pulls the villa into the IFI even though the family legally owns paper shares rather than stones: the shares count to the extent they represent the underlying French house, after applying the ratio of taxable real-estate value to total company assets.

That SCI fraction is also where over-taxation most often creeps in, and a very recent supreme court decision shows how courts police it. Many British-owned SCIs are pure asset-holding vehicles with no genuine business, and article 966 of the CGI confirms that mere management of a company’s own property portfolio is not an industrial, commercial or professional activity — so the family’s SCI cannot escape the IFI by dressing itself up as a business. But the valuation of those shares must still be honest. On 9 July 2025 the commercial chamber of the Cour de cassation, in decision no. 24-13.540, laid down the governing principle: “la valeur vénale des parts des sociétés civiles immobilières doit être appréciée en tenant compte de tous les éléments permettant d’obtenir un chiffre aussi proche que possible de celui qu’aurait entraîné le jeu normal de l’offre et de la demande” — the market value (valeur vénale, the price a sale would fetch on the open market) of SCI shares must reflect every factor that would bring the figure as close as possible to normal supply-and-demand bargaining. In that case the taxpayer, already granted two 10 per cent discounts (one for illiquidity of the buildings, one for illiquidity of the shares), demanded a third 10 per cent discount for deemed co-ownership constraints; the Court approved the appeal court’s refusal, holding that an SCI shareholder is not in the position of a co-owner in indivision (the French form of undivided joint ownership) and could not stack an extra discount on top. The lesson for British SCI owners is two-sided: genuine discounts for illiquidity are accepted and should be claimed with evidence, but invented or duplicated discounts are rejected — and, by the same token, an assessment that values your SCI shares at the full bricks-and-mortar price with no discount at all contradicts this case law and can be challenged.

Usufruct arrangements, common in Franco-British estate planning where parents keep a life interest and children hold the nue-propriété (bare ownership), follow a special and often misunderstood rule in article 968 of the CGI: assets burdened with a usufruct, a right of habitation or a personal right of use are “compris dans le patrimoine de l’usufruitier ou du titulaire du droit pour leur valeur en pleine propriété” — included in the usufructuary’s (or right-holder’s) estate at their full-ownership value. The bare owner therefore declares nothing for that property while the usufruct lasts, and the usufructuary declares the whole. British families frequently get this backwards, with both generations declaring a share or neither declaring at all. Note the narrow exception for certain divided-ownership gifts and bequests, which requires the usufruct not to have been sold or given away — check the precise conditions with your notaire (the French public legal officer who handles conveyancing and estates) before relying on it.

Against the gross assets, genuine debts are deductible to reach the net value — but only debts that exist at 1 January, that are the taxpayer’s personal burden, and that were taken on to acquire, improve or preserve taxable property. In practice this means the outstanding capital of the mortgage used to buy the French house, qualifying improvement loans, and a proportionate share of an SCI’s property debt passed through to the shares. Consumer credit, loans for a car or a boat, debts linked to exempt business property, and loans from family members without proper written terms and actual repayments are routinely rejected. The administration applies detailed anti-avoidance caps — on interest-only (in fine) loans, on loans taken out from a company the taxpayer controls, and on loans from close relatives — so a British buyer who borrowed from parents in London to buy in France must be able to produce the loan agreement, the transfer trail and the repayment record. Because only the position at 1 January counts, a mortgage fully repaid in March still reduces that year’s IFI, while a loan taken out in February does not. Finally, remember what stays outside the base altogether: household contents and cars, financial investments such as bank balances and shares in genuinely operating companies, and — subject to strict conditions on genuine professional use set out on the official persons and property page for the IFI — property genuinely assigned to your own main professional activity. A gîte business run through a company that merely manages its own cottages will not qualify, following the article 966 logic above.

II. How your IFI bill is worked out, declared and challenged after Brexit

A. How does the tax office value your French houses and work out what you owe?

Valuation starts from a deceptively simple principle stated in article 973 of the CGI: IFI assets are valued “suivant les règles en vigueur en matière de droits de mutation par décès” — under the rules used for death duties, meaning open-market value at the relevant date, here 1 January. The same article then grants the single most valuable allowance in the whole regime: “un abattement de 30 % est effectué sur la valeur vénale réelle de l’immeuble lorsque celui-ci est occupé à titre de résidence principale par son propriétaire” — a 30 per cent reduction applies to the true market value of a building occupied as its owner’s main residence, with only one building eligible per jointly taxed household. For a British family living year-round in its French house, this allowance removes nearly a third of the value before the threshold test and before the rates; omitting it is one of the commonest assessment errors, and it is also one of the easiest to correct. For a British non-resident whose French property is by definition a second home, the allowance is unavailable — the holiday house is valued gross — which is precisely why non-residents cross the threshold on houses that would sit comfortably below it for a resident occupier.

How is that market value established in the first place? The administration typically reasons by comparison (par comparaison), citing recent sales of similar properties in the same area, and the courts require it to do that exercise seriously. A published ruling of the commercial chamber of the Cour de cassation, decision of 27 March 2019, no. 18-10.933 — decided under the former wealth tax but stating the valuation principle the IFI inherited unchanged — defines the standard in terms you can quote back at an over-optimistic valuation: “la valeur vénale d’un immeuble correspond au prix qui pourrait en être obtenu par le jeu de l’offre et de la demande sur un marché réel, compte tenu de la situation de fait et de droit dans laquelle l’immeuble se trouve lors du fait générateur de l’impôt” — market value is the price obtainable through supply and demand on a real market, given the factual and legal situation of the building when the tax falls due. In that case the Court upheld a detailed comparison: the adjustment notice had described the taxed Paris town house (location, year of construction, structure, room layout, weighted floor area with the calculation shown, garden, private-road access) and, for each tax year, three sales of buildings in the same arrondissement with address, year, materials, floors, terrace or garden and weighted area. Only that level of concrete, like-with-like comparison made the reassessment lawful. The practical test for your own notice is therefore straightforward: if the tax office values your stone farmhouse by reference to renovated new-builds near a sought-after village, to sales two valleys away, or to asking prices rather than completed sales, its comparables fail the test this decision sets. Equally, the 2019 ruling confirms that co-ownership in indivision does not automatically earn an extra discount: the Court approved an appeal court finding that the state of undivided ownership had not affected value where the spouses held their main home jointly, had never mentioned the co-ownership in their returns, and were unlikely ever to sell a share separately. Discounts must be proved with facts — tenancy in place, dilapidation, planning constraints, poor access, co-ownership that genuinely blocks sale — not asserted as of right.

Once values are settled, the arithmetic is mechanical and is set by article 977 of the CGI. The progressive rates apply to slices of net taxable wealth: nothing up to 800,000 euros, 0.50 per cent from 800,001 to 1,300,000 euros, 0.70 per cent from 1,300,001 to 2,570,000 euros, 1 per cent to 5,000,000 euros, 1.25 per cent to 10,000,000 euros, and 1.50 per cent above. Because liability only begins at 1,300,000 euros, the 0.50 per cent slice always applies in full to a taxpayer just over the threshold — a 1,400,000-euro estate pays 0.50 per cent on 500,000 euros plus 0.70 per cent on 100,000 euros, before reliefs. A smoothing relief (décote) softens the cliff edge for estates between 1,300,000 and 1,400,000 euros: the tax computed under the scale “est réduit d’une somme égale à 17 500 €-1,25 % P, où P est la valeur nette taxable du patrimoine” — reduced by 17,500 euros minus 1.25 per cent of the net taxable wealth. A cap (plafonnement) linked to your income can then reduce the total where IFI plus income taxes would take a disproportionate share of what you earned; the official IFI calculation page describes the mechanism and its conditions, and it is worth testing whenever the bill looks large beside modest retirement income. Finally, gifts to qualifying research, higher-education, public-interest and integration bodies can be set against the IFI within statutory limits — relevant to charitably minded British residents who already support French causes.

Declaration follows the income-tax calendar. Under article 982 of the CGI, liable taxpayers report the gross and net taxable values on the annual return provided for by article 170 and attach schedules, drawn up on the administration’s model, listing and valuing each asset. In everyday terms, described on the official IFI declaration and payment page: each spring, within the same deadlines as the income-tax return, you file form 2042-IFI with its annexes alongside your income return at your local tax office (service des impôts des particuliers). British non-residents with no French income return file the 2042-IFI through the non-residents tax office, and everyone — resident or not — must keep the valuation evidence (estate-agent appraisals at 1 January, notarial price databases, loan statements, SCI accounts) because the return is self-assessed and the administration may audit it for several years. Late or missing IFI schedules draw interest and penalties on top of the tax, so a British owner who discovers the obligation late should regularise spontaneously rather than wait for a reassessment: spontaneous correction almost always costs less than a reassessment with penalties after an audit.

B. How do you challenge an IFI assessment that looks wrong?

Start by reading the assessment the way a litigator would, before any deadline runs. Check five things in order: the persons taxed (are both spouses correctly shown; are minor children’s assets correctly attributed; is the usufructuary rather than the bare owner taxed on burdened property); the residence base (worldwide or French-only — see Part I, including the five-year newcomer shelter); the inventory (does every property and every SCI fraction belong in your estate, and is nothing double-counted between direct ownership and company shares); the values (is the 30 per cent main-home allowance applied; are genuine discounts for tenancy, condition or illiquidity reflected; are the comparables truly comparable under the 2019 decision above); and the debts (is every qualifying loan deducted at its 1 January balance). Then gather the counter-evidence immediately while it is fresh: two independent written appraisals dated around 1 January, photographs of defects, the lease if the property is tenanted, loan statements, SCI balance sheets, and proof of residence and of the five prior non-resident years if the base itself is disputed. An overvaluation challenge without alternative figures and comparable sales almost never succeeds; a file with dated appraisals and three genuine local sales often settles.

French procedure then imposes a mandatory first step before any court: the prior claim to the administration (réclamation préalable). Article R*190-1 of the LPF provides: “Le contribuable qui désire contester tout ou partie d’un impôt qui le concerne doit d’abord adresser une réclamation au service territorial” — a taxpayer wishing to dispute all or part of a tax must first send a claim to the local office of the tax administration for the place of taxation (for disputes about the market value of buildings, the office where the property stands). Send it by registered letter with acknowledgement of receipt (lettre recommandée avec accusé de réception) or through your secure online tax mailbox (messagerie sécurisée), identify the tax, the year and the amount disputed, state each ground separately with its legal basis and attach the evidence. The claim belongs to the contentious jurisdiction defined by article L190 of the LPF, which covers claims seeking “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” — either correction of errors in the base or calculation, or the benefit of a right under legislation — exactly what an IFI valuation or scope dispute is.

Time limits are strict and missing them ends the case whatever its merits. Article R*196-1 of the LPF requires claims to reach the administration “au plus tard le 31 décembre de la deuxième année suivant celle” of the relevant event — no later than 31 December of the second year following, in particular, “la mise en recouvrement du rôle ou de la notification d’un avis de mise en recouvrement” (the recovery roll or the collection notice). For an IFI bill collected in autumn 2026, the claim must therefore arrive by 31 December 2028. If the administration rejects the claim expressly or stays silent for six months (an implied rejection), you may take the dispute to the tribunal judiciaire (the ordinary civil court with a tax chamber), which has heard these valuation cases since the former wealth-tax era — both supreme court decisions cited above reached the Cour de cassation from that route. Before the court, the strongest British-owner arguments in practice are: defective comparables under the 2019 ruling; the omitted 30 per cent main-home allowance; SCI shares valued gross with no illiquidity recognition contrary to the 2025 ruling; the wrong residence base or a forgotten five-year newcomer shelter; omitted qualifying debts; and usufruct property attributed to the wrong generation. Two final cautions: complaining does not automatically suspend collection, so diarise the payment date and, if the sum is large, ask the tax office in writing about payment arrangements rather than simply not paying; and never invent a valuation — a reasoned, documented figure a little below the assessment beats an aggressive figure with nothing behind it, because the judge appoints an expert or decides between two reasoned positions, and credibility is everything.

Conclusion

The IFI looks exotic to British eyes, but it rewards the same discipline as any British tax dispute: establish the correct taxable person and the correct base first, value honestly with dated evidence, declare on time on the right form, and challenge precisely and within the time limit when the assessment is wrong. For a British owner after Brexit that means checking residence and the five-year newcomer shelter before anything else, counting SCI shares only to their real-estate fraction with proper discounts, applying the 30 per cent main-home allowance where it belongs, deducting every genuine loan at its 1 January balance, and — when the bill still looks wrong — filing a documented prior claim to the local tax office within the deadline and taking a rejected claim to the tribunal judiciaire armed with the valuation case law above. Do that, and an alarming brown envelope becomes a manageable file; ignore the deadlines, and even the best argument dies unheard.

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