You bought the stone house in the Dordogne years ago, or you moved to France for good after Brexit and kept a flat in London, or the family SCI holds the villa near Antibes. Then a letter arrives, or your accountant asks an awkward question: what about the IFI? The impôt sur la fortune immobilière, France’s real-estate wealth tax, catches British owners on both sides of the Channel. If you live in France, it can reach your worldwide property once the total passes €1.3 million. If you still live in Britain, it reaches your French house and your shares in the family property company. And since Brexit you argue these points as a third-country national, with no European shield to hide behind. Two recent court decisions show how the fight plays out: in May 2026 the Paris civil court confirmed that non-residents holding French property through an SCI pay IFI and that their tax treaty does not save them, while in February 2025 the Nîmes appeal court confirmed a €5.2 million valuation because the owners could not prove their own declared figure was exaggerated. This article explains, in plain English with each French term translated, when you are liable, how the bill is calculated, what you can deduct, how to file, and how to challenge an assessment that gets it wrong.
I. Are you liable to IFI on your French property after Brexit
A. You live in France: worldwide property counts and the household pays together
If your domicile fiscal (tax home for income tax purposes) is in France, article 964 of the Code général des impôts (the French tax code) provides: « Sont soumises à cet impôt, lorsque la valeur de leurs actifs mentionnés à l’article 965 est supérieure à 1 300 000 € : 1° Les personnes physiques ayant leur domicile fiscal en France, à raison de leurs actifs mentionnés au même article 965 situés en France ou hors de France. » (CGI, art. 964). Everything above €1.3 million counts: the French house, but also a flat you kept in Manchester or a villa in Spain, because the base for residents is worldwide. The official service-public.fr guidance, verified 6 March 2026, confirms the test in plain terms: you pay IFI when the taxable net value of your non-business property exceeds €1,300,000 at 1 January (service-public.fr, IFI: persons and property concerned).
Three household points matter for British families. First, the tax is charged per foyer fiscal (tax household), not per person. The statute says: « Sauf dans les cas prévus aux a et b du 4 de l’article 6, les couples mariés font l’objet d’une imposition commune. » (CGI, art. 964). The same joint taxation applies to partners in a PACS (the French civil partnership) and to couples in acknowledged cohabitation. So a married couple adds both spouses’ property together before testing the €1.3 million line; two portfolios of €800,000 each are taxable jointly. If you married in England and are unsure which property regime owns the house, our guide on matrimonial regimes for British couples in France walks through the answer. Second, property belonging to your minor children counts when you have legal administration of their assets (CGI, art. 965, 1°: CGI, art. 965). Third, everything is assessed once a year: « Les conditions d’assujettissement sont appréciées au 1er janvier de chaque année. » (CGI, art. 964). A sale completed on 15 January does not erase liability for that year; a purchase completed on 2 January does not create it.
New arrivals get one soft landing. If you were not fiscally domiciled in France during the five calendar years before the year you settled, you are taxed for five years only on the property mentioned in paragraph 2 — broadly, French property — in the words of the statute, such newcomers « ne sont imposables qu’à raison des actifs mentionnés au 2° » until 31 December of the fifth year after settling (CGI, art. 964; service-public.fr). After that window, worldwide property enters the base. If your residence position itself is disputed — France says you live here, HMRC says you live there — read our guide on the France-UK tie-breaker for dual tax residence before you concede the worldwide base, and our walkthrough of the first French tax return for the forms that fix your residence date.
B. You still live in Britain: your French house and your SCI shares are taxable in France
Keeping your tax home in the United Kingdom does not move your French house out of the French tax net. Article 964 taxes « Les personnes physiques n’ayant pas leur domicile fiscal en France, à raison des biens et droits immobiliers mentionnés au 1° de l’article 965 situés en France et des parts ou actions de sociétés ou organismes mentionnés au 2° du même article 965» (CGI, art. 964), with the shares counted only up to the slice of their value that represents those French bricks and mortar. The French administration’s own guidance for non-residents confirms the same test: net French property above €1,300,000 means IFI, subject to the applicable tax treaties (impots.gouv.fr, non-resident IFI guidance, updated 28 February 2025). Only French property counts for you — your English home is invisible to the IFI — but every French asset counts, whether you hold it directly or through a company.
Most British families hold through a SCI, the société civile immobilière (a non-trading French property company, usually family-owned). The SCI does not shield the property from IFI. Article 965 brings into the base the « parts ou actions des sociétés et organismes établis en France ou hors de France » held by the taxpayer, but only « à hauteur de la fraction de leur valeur représentative de biens ou droits immobiliers détenus directement ou indirectement par la société ou l’organisme » (CGI, art. 965). In plain terms: your SCI shares count up to the slice of their value that represents French bricks and mortar. Shares in a company with a genuine industrial, commercial, craft, farming or professional activity escape only where your family holds less than 10% of the capital and voting rights — a classic family SCI holding a holiday villa never qualifies for that carve-out.
The treaty argument fails too. On 5 May 2026 the Paris judicial court (9th chamber, 1st section, RG 24/13163) rejected a claim by a Dutch-resident couple holding French property through an SCI who argued their treaty protected them. The court held that « la convention franco-néerlandaise ne fait pas obstacle à cette imposition » and concluded: « en l’absence de stipulation expresse contraire, la France conserve le droit d’imposer les biens immobiliers situés sur son territoire, notions intégrant les parts de SCI propriétaires d’immeubles, et ce même lorsqu’ils sont détenus par des non-résidents » (TJ Paris, 5 May 2026, RG 24/13163). The reasoning turns on domestic law plus the absence of any contrary treaty clause, not on European Union membership, so it reads across directly to British owners: since Brexit you are third-country nationals, and no treaty exempts your French house or your SCI shares from IFI. Our companion guide on British family trusts and French tax covers the parallel trap where a trust, rather than an SCI, holds the property.
One family situation deserves its own warning: split ownership. Where a surviving parent holds the usufruit (a lifetime right to use the property and take its income, roughly a life interest) and the children hold the nue-propriété (the bare ownership underneath), article 968 provides: « Les actifs mentionnés à l’article 965 grevés d’un usufruit, d’un droit d’habitation ou d’un droit d’usage accordé à titre personnel sont compris dans le patrimoine de l’usufruitier ou du titulaire du droit pour leur valeur en pleine propriété. » (CGI, art. 968). The default is harsh: the whole full-ownership value sits in the surviving holder’s base. Only in listed cases — a surviving spouse’s statutory usufruct, a sale where the seller kept the usufruct for a stranger-buyer, a gift to a charity with reserved use — is the value split between holder and bare owners using the article 669 scale. British couples who organised a démembrement (split of ownership) for succession purposes must therefore re-check the IFI position: the parent who kept the usufruct may have crossed the €1.3 million line alone. Where the family tension behind the split is a second marriage, our guide on second spouses and children of a first marriage explains the succession side.
II. How the bill is built, declared and challenged
A. What your French property is really worth on 1 January, what comes off, and what rate applies
Valuation starts from a simple rule with a sharp edge. Article 973 I states: « La valeur des actifs mentionnés à l’article 965 est déterminée suivant les règles en vigueur en matière de droits de mutation par décès. » (CGI, art. 973). You value as if the property passed on death: the valeur vénale (open-market value) at 1 January. The Nîmes appeal court gave the working definition in an IFI case on 13 February 2025 (RG 23/03035): « La valeur vénale d’un bien est constituée par le prix qui pourrait en être obtenu par le jeu de l’offre et de la demande dans un marché réel au jour de la mutation et elle est déterminée à partir d’une comparaison tirée de la cession de biens intrinsèquement similaires. » (CA Nîmes, 13 February 2025, RG 23/03035). In that case the owners had declared land at their own figure, then tried to cut it after a development deal collapsed; the administration answered with comparable sales between September 2017 and December 2018 averaging €68.65 per square metre, and the court fixed the site at €5,219,556 for 2019 IFI, reversing the first judges. The lesson for British owners: an estate agent’s letter is not a valuation. Collect genuine comparable sales of similar properties, close in time and place, and keep them — the administration will bring its own.
One relief softens the figure, but only for your main home. The same article 973 I continues: « 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. » Only one property per jointly taxed household qualifies, and it must be your résidence principale (the home where you actually live). A British owner living in Kent with a second home in Provence gets no 30% cut on the Provençal house. A British resident living year-round in that house does — a €1.6 million main home enters the base at €1.12 million. Claiming the relief on the wrong property, or on business premises woven into the home, is exactly the kind of exemption claim courts throw out when the owner brings no proof: in February 2026 the Nancy judicial court dismissed an IFI taxpayer whose file contained only the extra assessments and complaint letters, holding « Ces éléments ne sont de nature à établir ni la réalité, ni a fortiori la répartition intérieure des usages » given to the rooms (TJ Nancy, 13 February 2026, RG 23/00802).
Debts come off next, within tight walls. Article 974 allows deduction of « les dettes, existantes au 1er janvier de l’année d’imposition, contractées par l’une des personnes mentionnées au 1° de l’article 965 et effectivement supportées par celle-ci, afférentes à des actifs imposables » (CGI, art. 974). Eligible debts are acquisition loans, genuine repair and maintenance costs borne by the owner, improvement, building and extension costs, and property taxes (not income tax on the rents). Three traps catch British owners. First, family and in-house loans: loans from yourself, your spouse, your PACS partner, your cohabiting partner or your minor children are never deductible, and loans from parents, other children, siblings, or from a company your family controls are deductible only if you prove normal arm’s-length terms — real deadlines, real amounts, real repayments. Second, bullet loans (in fine, where capital repays only at the end) are not deducted at face value: each year you deduct the total minus a slice for each year elapsed, so a €600,000 twenty-year bullet loan counts only €570,000 after one year. Third, loans funding the SCI from its own shareholders are stripped out of the share valuation under article 973 II unless you prove the loan had no mainly fiscal purpose, and above €5 million of taxable property, debt exceeding 60% of the value counts only half for the excess unless you prove it was not mainly fiscal.
The rate scale is short and the threshold has a cushion. Article 977 taxes the net base at 0% to €800,000, 0.50% from €800,000 to €1.3 million, 0.70% to €2.57 million, 1% to €5 million, 1.25% to €10 million and 1.50% above (CGI, art. 977). Take a British-resident couple with a €1.5 million net base: nothing on the first €800,000, €2,500 on the next €500,000, €1,400 on the last €200,000 — a €3,900 bill. Just over the line, the décote (smoothing relief) applies: « le montant de l’impôt calculé selon le tarif prévu au tableau du 1 est réduit d’une somme égale à 17 500 €-1,25 % P, où P est la valeur nette taxable du patrimoine. » At €1.35 million that relief is worth €625. Two further reducers exist. Gifts to research bodies, recognised charities and similar organisations give a credit of « dans la limite de 50 000 €, 75 % du montant des dons en numéraire » (CGI, art. 978). And residents of France — only them — can invoke the cap of article 979: « L’impôt sur la fortune immobilière du redevable ayant son domicile fiscal en France est réduit de la différence entre, d’une part, le total de cet impôt et des impôts dus en France et à l’étranger au titre des revenus et produits de l’année précédente, calculés avant imputation des seuls crédits d’impôt représentatifs d’une imposition acquittée à l’étranger et des retenues non libératoires et, d’autre part, 75 % du total des revenus mondiaux nets de frais professionnels de l’année précédente, après déduction des seuls déficits catégoriels dont l’imputation est autorisée par l’article 156 » (CGI, art. 979). A British owner still resident in the UK, taxed only on French property, gets the rates and the gifts credit but never the cap — a structural reason the bill bites harder from London than from Lyon.
B. How to file the return from London or Lyon and how to fight an assessment
IFI is a self-assessed tax: you declare, then the administration can check. Article 982 I requires: « Les redevables mentionnent la valeur brute et la valeur nette taxable des actifs mentionnés à l’article 965 sur la déclaration annuelle prévue à l’article 170 », and « Ils joignent à cette déclaration des annexes conformes à un modèle établi par l’administration, sur lesquelles ils mentionnent et évaluent les éléments de ces mêmes actifs. » Spouses and PACS partners must sign jointly (CGI, art. 982). In practice, residents file form 2042-IFI with the yearly income return and its annexes valuing each asset. Non-residents file the same forms to the dedicated non-residents’ tax office (the SIPNR, 10 rue du Centre, TSA 10010, 93465 Noisy-le-Grand CEDEX); if you file no French income return at all, use the standalone 2042-IFI-COV form with its annexes, and pay online once the bill exceeds €300 (impots.gouv.fr, non-resident IFI guidance; impots.gouv.fr, form 2042-IFI). File even when the calculation is close: the return starts the limitation clock, while silence invites an ex officio assessment built on the administration’s comparables rather than yours. British landlords already filing French rental declarations will find the rhythm familiar — see our guide on UK rental income declared in France — and owners who also pay the local bill should keep the two taxes distinct with our guide on taxe foncière for British owners.
Challenges turn on proof, and the burden points both ways depending on who attacks whose figure. If you declared a value and later claim it was exaggerated, you carry the burden. The Nîmes court applied article R.194-1 of the tax procedure book: once the taxpayer agreed or stayed silent and then complains, « il peut obtenir la décharge ou la réduction de l’imposition, en démontrant son caractère exagéré. » The owners there failed — « les intimés sont défaillants dans l’administration de la preuve qui leur incombe » — and their €7.6 million declared figure became a €5.2 million court-fixed value with costs and €3,000 under article 700 (CA Nîmes, 13 February 2025, RG 23/03035). Think twice, then, before signing a high figure to speed a mortgage or a sale: your own declaration is Exhibit One against you. If instead the administration attacks your valuation, the burden flips to them. In December 2024 the Paris appeal court (Pôle 5, chamber 10, RG 22/12469) confirmed a first-instance judgment holding « que l’administration fiscale ne rapporte pas la preuve du caractère insuffisant des évaluations faites par Monsieur [B] des parts sociales dont il était propriétaire au titre de sa déclaration », and it closed with « Confirme le jugement entrepris en toutes des dispositions », ordering full discharge of the extra assessments and €3,000 under article 700 (CA Paris, 16 December 2024, RG 22/12469). That case concerned SCI shareholdings under the former solidarity tax, but the method — market value tested against comparables, insufficiency to be proved by whoever alleges it — is exactly the method article 973 I now commands for IFI.
The practical file, then, has five folders. First, a valuation pack at each 1 January: comparable sales of similar properties, the notaire’s estimate, photographs and diagnostics showing defects that lower value, and the SCI accounts with the property-to-total-assets ratio for the share fraction. Second, the debt pack: loan offers, amortisation tables, proof the debt existed at 1 January and that you personally bear it, and for any family or company-linked loan, written arm’s-length terms with actual repayments. Third, the relief pack: proof you actually occupy the main home, charity receipts for the 75% credit, and for French residents the income computation behind the 75% cap. Fourth, the filing pack: returns, annexes, proof of sending to the SIPNR where relevant. Fifth, the challenge pack: the assessment, a quantified réclamation (formal claim to the administration) filed in time, and then, if rejected, proceedings before the judicial court — the forum that decided the Paris, Nancy, Carpentras and Nîmes cases above. A win can also earn moratory interest on the discharged sum, as the Carpentras court ordered a €42,045 discharge « assorti des intérêts moratoires institués par l’article L.208 du Livre des procédures fiscales » (CA Nîmes, 13 February 2025, RG 23/03035). Start the paper trail before the administration writes, answer each line of any reassessment with the article it offends, and never sign a figure you cannot defend with comparables.
Conclusion
IFI follows the British owner, not the other way round. Live in France and your worldwide property counts once the household passes €1.3 million, with only a five-year window taxing French assets alone. Live in Britain and your French house plus the French-property slice of your SCI shares count, with no treaty escape — the Paris court of May 2026 said so to non-resident SCI holders in terms that apply fully to Britons. Value is market value at 1 January proved by comparables of similar properties; the 30% cut belongs only to the home you actually occupy; debts count only if they existed at 1 January, relate to taxable assets and survive the family-loan and bullet-loan traps; the scale runs 0.50% to 1.50% with a smoothing relief just above the threshold; gifts cut the bill by 75% within €50,000; and the 75%-of-income cap belongs to French residents alone. File on 2042-IFI with full annexes, to the non-residents’ office if you live in the UK, and challenge with numbers: whoever attacks a valuation must prove it, whether that is you against your own declared figure or the administration against yours. Build the five folders now and the bill becomes a calculation you control rather than a letter you fear.