You moved to France after Brexit, bought or rented your French home, and kept the house in Manchester, Bristol or London “just in case”. For income tax you already know the drill: France taxes its residents on worldwide income. What many British arrivals discover one or two years too late is that France also runs an annual tax on property wealth, the impôt sur la fortune immobilière (IFI, the French real-estate wealth tax), and that once you are resident here for tax purposes your English house counts towards it. There is no £1 million-style UK allowance to hide behind, no relief under the double tax treaty for this particular tax, and the bill is calculated on the net value of your property on 1 January each year. The good news is that newcomers get a five-year shelter for foreign property, that the family home enjoys a 30 per cent reduction, that mortgages are deductible, and that a cap linked to your income can cut the bill. This guide explains who is caught, how the calculation works with a worked British example, and how to challenge an assessment you consider wrong.
I. French tax residence pulls your British home into the IFI net
The single question that decides everything is whether you have your domicile fiscal (French tax residence) in France. If the answer is yes and the net value of your property worldwide exceeds €1,300,000, you are within the tax. If the answer is no, only your French property can be taxed. The two situations are governed by the same article, and the difference between them is worth understanding before you do anything else.
A. Resident in France? Your house in Britain counts, not just your flat in France
Article 964 of the Code général des impôts (CGI, the French general tax code) provides that the persons liable are, first, “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.” In plain English: individuals with their tax residence in France are liable on the listed assets whether they are situated in France or outside France. Your London terrace, your buy-to-let in Leeds, your French apartment and your shares in a property company all sit in the same base. The service-public.fr guidance for individuals confirms the point in practical terms: where your tax residence is in France, the tax covers all the buildings, property rights and property-company shares held in France and abroad by your household (your foyer, essentially you, your spouse or civil partner and your minor children). That official page is here: Impôt sur la fortune immobilière (IFI) : personnes et biens concernés.
Three features of the base matter particularly for British readers. First, the €1,300,000 figure is a threshold, not the point where the rate scale starts. Article 964 taxes you only once the value of the listed assets exceeds €1,300,000, while the rate scale itself begins at €800,000. In other words, a worldwide net property position of €1,250,000 produces no IFI at all, but €1,350,000 puts the whole scale into play, with a smoothing reduction (the décote) between €1,300,000 and €1,400,000 that Part II works through. Second, the base is net and dated: article 965 of the CGI states that “L’assiette de l’impôt sur la fortune immobilière est constituée par la valeur nette au 1er janvier de l’année” of the buildings and property rights held by the persons concerned and by their minor children where they have legal administration of the children’s property, plus shares in companies and entities established in France or abroad, but only in proportion to the underlying property. That second limb catches the British landlord who holds a French flat through an English company or a French société civile immobilière (SCI, a non-trading property company): the shares are taxable up to the fraction of their value representing property held directly or indirectly. If your ownership chain runs through a family SCI, the mechanics and the succession side are examined in this companion guide: how a British family SCI is set up, taxed and passed on. Third, only a genuinely similar foreign tax can be credited. Article 980 of the CGI provides that “Le montant des impôts dont les caractéristiques sont similaires à celles de l’impôt sur la fortune immobilière acquitté, le cas échéant, hors de France est imputable sur l’impôt exigible en France.” Keep the proof of any such foreign wealth tax paid, because taxes that are not levied on net property wealth do not qualify for this credit. On the treaty side, the British government’s own guidance for its nationals in France points to the bilateral double tax agreement as the mechanism that prevents the same income being taxed in both countries. That protection concerns income: it does not cap a wealth tax, and it does not remove your London home from the French base. The same guidance reminds Britons that assets held outside France, including bank accounts, securities and property, must be declared separately from the annual tax return, which is a useful discipline for IFI purposes too, since the French return discussed in Part II requires the same completeness.
A final trap for the arrival year: you can be tax-resident in both countries at once for the year of the move. The tie-breaker in the France-United Kingdom treaty and the mechanics of the first French return, including split years on the British side, are dealt with in this companion guide: moving to France mid-year, residence tie-break and the first return. Settle residence first, because everything in this article flows from it.
B. The five-year shelter for newcomers, and the position when you leave
New arrivals get breathing space. Article 964 continues: individuals who were not fiscally domiciled in France during the five calendar years before the year in which they establish their French tax residence “ne sont imposables qu’à raison des actifs mentionnés au 2°”, that is, only on the France-situated base that applies to non-residents, and this lasts until 31 December of the fifth year following the year residence was established. The service-public.fr page states the same rule for the public: newcomers who transfer their tax residence to France after living abroad for the previous five calendar years are taxed only on property owned in France. Concretely, a British family that settles in Lyon in 2026 after five years in the United Kingdom leaves its Manchester house outside the IFI until the assessment for 2032, provided French tax residence is kept continuously; only the French home can trigger the tax in the meantime. Use those five years to plan rather than to forget: diary the expiry date, track the 1 January values, and decide in advance whether to sell, to borrow against, or simply to budget for the worldwide base when it arrives.
Mirror image: if you leave France and lose French tax residence, you fall back to the non-resident base, which covers only property situated in France and shares representing French property. Non-residents are never taxed on homes outside France. The departure itself raises separate questions, from the exemption window on selling your former French main home to the tax on unrealised gains when a substantial shareholder emigrates, and the sale-side mechanics are covered here: leaving France for Britain and selling your old French home. For IFI purposes the lesson is symmetrical and simple: residence is re-tested every year, the base follows residence, and the photograph is taken on 1 January.
II. Working out the bill, capping it, declaring it and fighting it
Once you know which base applies, four operations follow in order: value the property, subtract deductible debts, apply the rate scale, then check the income-linked cap. Each step has its own article, its own case law and its own typical disputes, and the declaration and challenge rules sit on top of all four.
A. Value on 1 January, subtract the mortgages, apply the scale
Valuation follows the death-duty rules, with one big family-home reduction. Article 973 of the CGI sends you to the valuation rules used for transfer duties on death, then adds that “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 can benefit where a couple is taxed jointly, and the reduction applies to the valeur vénale réelle (the true open-market value), not to a notional figure. Listed securities are valued on the last known price or the thirty-day average, and article 973 also neutralises certain intra-group and shareholder debts when valuing company shares, which matters for SCI planning. The courts define open-market value in terms every valuer recognises. In a wealth-tax valuation dispute over a Paris town house used as the family home, the Cour de cassation (Court of Cassation, France’s highest court for this litigation) held that “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” (Cass. com., 27 March 2019, no. 18-10.933). The decision was given under the former wealth tax, the impôt de solidarité sur la fortune (ISF, the solidarity tax on wealth that the IFI replaced on 1 January 2018), but the valuation formula was carried into article 973 and advisers still cite the case. Two practical points flow from it for British owners. First, the tax office values by comparison with similar properties, and comparisons must genuinely be comparable: age and materials alone are not enough if the essential characteristics differ, which is exactly what the litigation examined. Second, do not expect an extra discount simply because a couple owns the home in indivision (joint undivided ownership): the court upheld the legal 30 per cent reduction for the main home and refused to add a further allowance for the joint-ownership position the taxpayers had not even disclosed in their returns. Declare the legal position of each asset completely, then argue value, not the reverse.
Debts reduce the base, but only the right debts. Article 974 of the CGI provides that “Sont déductibles de la valeur des biens ou droits immobiliers et des parts ou actions taxables 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”, in proportion where relevant to the taxable fraction. Qualifying debts include acquisition loans, genuine repair and maintenance expenditure borne by the owner, improvement, construction, reconstruction and enlargement costs, and property taxes other than those normally borne by the occupier, while taxes on the income the property generates are excluded. Three conditions therefore decide every mortgage question: the debt must exist on 1 January, it must be effectively borne by the taxpayer, and it must relate to a taxable asset. A British owner with an interest-only remortgage used partly to buy a car will need to apportion; a loan taken out in February cannot help for that year’s photograph; and debts attached to exempt business property are outside the computation. Article 966 of the CGI adds a warning for structures: a company that merely manages its own property portfolio is not treated as carrying on an industrial, commercial, craft, agricultural or professional activity for these purposes, which limits exemption planning through holding vehicles (see article 966).
The rate scale is short and progressive. Article 977 of the CGI sets the tariff at 0 per cent up to €800,000, 0.50 per cent from €800,001 to €1,300,000, 0.70 per cent to €2,570,000, 1 per cent to €5,000,000, 1.25 per cent to €10,000,000 and 1.50 per cent above, with the smoothing reduction for net taxable wealth between €1,300,000 and €1,400,000 calculated as €17,500 minus 1.25 per cent of the net taxable value. Take a worked British example for the 2026 assessment, photographed on 1 January 2026. A couple owns a Paris apartment worth €850,000, occupied as their résidence principale (main home), with a French acquisition mortgage of €200,000 outstanding on 1 January, plus a London house worth £800,000, owned outright. At an illustrative £1 = €1.175 on the valuation date, the London house represents €940,000; use the actual rate on the date in your own file. Taxable base: Paris (€850,000 less 30 per cent = €595,000) plus London (€940,000) less the deductible loan (€200,000) = €1,335,000, which exceeds the €1,300,000 threshold, so the tax bites. Scale computation: 0.50 per cent on the €500,000 slice from €800,000 to €1,300,000 = €2,500; 0.70 per cent on the €35,000 slice from €1,300,000 to €1,335,000 = €245; subtotal €2,745. Smoothing: €17,500 less 1.25 per cent of €1,335,000 (€16,687.50) = €812.50; tax before cap = €1,932.50. The same couple with a London house worth £600,000 instead would sit at about €1,100,000 net and pay nothing. Small valuation movements around the threshold change everything, which is why the valuation evidence in the next section matters so much. Gifts can also trim the bill: article 978 of the CGI allows 75 per cent of certain cash and listed-share gifts to research, higher-education and similar bodies to be set against the tax, up to €50,000 (see article 978).
Split ownership needs its own paragraph, because British wills and French succession law collide here. The default rule in article 968 of the CGI is that property burdened with a usufruit (usufruct, a lifetime right to use the property and take its income), a right of habitation or a personal right of use “sont compris dans le patrimoine de l’usufruitier ou du titulaire du droit pour leur valeur en pleine propriété”, that is, taxed in the hands of the usufructuary for the full-ownership value. The exception covers the classic surviving-spouse position: where the usufruct arises by law for the spouse, notably under article 757 of the Code civil (Civil Code), under which “le conjoint survivant recueille, à son choix, l’usufruit de la totalité des biens existants ou la propriété du quart des biens lorsque tous les enfants sont issus des deux époux”, the usufructuary and the nu-propriétaire (bare owner) are each taxed on their fraction using the article 669 scale, which runs from 90 per cent usufruct under age 21 down to 10 per cent over age 91 (see article 669 and article 968). A British widow who took a lifetime interest in the Dordogne house under an English will, rather than a French legal usufruct, may therefore find the whole value taxed in her hands: take advice on the characterisation before filing, and keep the grant of probate, the will and the French death-duty return consistent with the IFI position.
B. The income-linked cap, the return, and challenging the assessment
The plafonnement (statutory cap) protects the asset-rich but income-poor, a common British retiree profile. Article 979 of the CGI reduces the IFI of a French-resident taxpayer by the difference between, on one side, the IFI plus the taxes due in France and abroad on the previous year’s income and products, and on the other side, “75 % du total des revenus mondiaux nets de frais professionnels de l’année précédente”, after deduction of allowable losses, exempt income and income subject to a flat-rate levy realised in France or abroad. In the worked example above, suppose the couple’s previous-year worldwide net income was €60,000, so that 75 per cent is €45,000, and suppose their total taxes (IFI plus French and foreign income taxes computed before foreign-tax credits and non-final withholding) came to €50,000: the IFI is reduced by the €5,000 excess. The leading case on the cap repays attention. In Cass. com., 28 March 2019, no. 17-23.671, again under the former wealth tax whose cap mechanism the IFI reproduces, the court approved counting undistributed partnership profits in the income side of the ratio, holding that “les revenus nets du contribuable entrant dans le calcul du plafonnement de l’ISF devant s’entendre des revenus réalisés et non nécessairement perçus par le contribuable”, and it rejected the human-rights attack on the mechanism, holding that “le mécanisme de plafonnement de l’ISF en fonction d’un rapport entre le total des impôts et les revenus nets des redevables participe à l’exigence de proportionnalité, en ce qu’il vise à tenir compte des capacités contributives du redevable”. Two lessons for British claimants: put every realised item, including a property gain realised inside an SCI, on the income side even if nothing was distributed, because the administration will; and frame a cap dispute as a computation dispute with documents, not as a bare fairness plea, because the courts treat the cap itself as the proportionality answer. Note also the anti-avoidance tail of article 979: dividends routed through a controlled company to defeat the cap can be pulled back into the computation where the arrangement mainly seeks a tax advantage contrary to the provision’s purpose.
Declaration is part of the income return, not a separate exercise. Article 982 of the CGI requires liable persons to enter “la valeur brute et la valeur nette taxable des actifs mentionnés à l’article 965 sur la déclaration annuelle prévue à l’article 170”, with supporting schedules in the administration’s format valuing each component; cohabiting partners and minor children’s property have their own reporting lines. File late, file short or file inconsistently with the land registry, the mortgage statements and the death-duty file, and the file becomes a rectification waiting to happen. If property is held through a British family trust, the trustees’ own French reporting duties run alongside yours and are examined here: British family trusts, French declaration, IFI and succession.
When the administration disagrees, it notifies a proposition de rectification (proposed adjustment), you reply with observations, and the dispute then follows the classic path visible in both cited decisions: rejection of the claim (réclamation), then court action for annulment of the rejection and discharge of the additional tax. The procedure has teeth on both sides. The adjustment must be reasoned as article L.57 of the Livre des procédures fiscales (LPF, the tax procedure code) requires, a point the valuation decision expressly verified before reaching the merits; the conciliation commission’s opinion must be reasoned too. Your réclamation belongs to the contentious jurisdiction where it seeks correction of base or computation errors or the benefit of a legislative right, and article L.190 of the LPF allows claims from receipt of the reply to your observations or after the statutory windows it lists (see article L.190). Interest and penalties then set the stakes of fighting versus conceding. Article 1727 of the CGI charges intérêt de retard (late-payment interest) on fiscal debts not paid on time, but provides a shield the careful taxpayer should use systematically: “L’intérêt de retard n’est pas dû : 1. Au titre des éléments d’imposition pour lesquels un contribuable fait connaître, par une indication expresse portée sur la déclaration ou l’acte, ou dans une note annexée, les motifs de droit ou de fait qui le conduisent à ne pas les mentionner en totalité ou en partie”, or to value them as he does. Where the valuation of the London house or the deductibility of a loan is genuinely debatable, an express note annexed to the return, setting out the method, the comparables and the exchange rate used, can neutralise interest even if the administration later wins the point. Article 1729 of the CGI then grades the penalties: “40 % en cas de manquement délibéré” and 80 per cent for abuse of rights, fraud or concealment of part of a contract price. A reasoned file with an agent’s valuation, the land-registry extract, the 1 January exchange-rate printout, the mortgage statements and the cap computation will rarely attract the deliberate-failure uplift; an undeclared London house discovered through exchange of information invites it. The service-public.fr calculation page usefully summarises the whole chain for the public: calcul de l’impôt sur la fortune immobilière.
Conclusion
Once France is your tax home, the IFI looks past the Channel: the London house, the French apartment and the property-company shares form a single worldwide base photographed every 1 January, taxable above €1,300,000 net, with only a genuinely similar foreign wealth tax available as a credit. Against that breadth, the code offers four precise tools: the five-year newcomer shelter for foreign property, the 30 per cent reduction on the main home valued at true open-market value, deduction of genuine acquisition and improvement debts, and the 75 per cent income-linked cap. Use them in that order, declare gross and net values with annexed evidence and an express note wherever a position is debatable, and challenge an adjustment through observations, reasoned claim and court action rather than silence. For British households the costly errors are always the same: forgetting the UK property exists for French purposes, missing the expiry of the five-year shelter, valuing by guesswork instead of comparables, and leaving the cap unclaimed. A file built on the articles cited above avoids all four.