You bought a flat in Lyon, a village house in the Dordogne or a studio in Paris before Brexit, and you now let it while living in London, Manchester or Edinburgh — or while settled in France yourself. Every spring the same questions return: where do you declare the rent, which French regime applies, do French social charges apply on top of income tax, and will HM Revenue & Customs tax the same rent again? Since the United Kingdom left the European Union, the tax mechanics have not changed — France still taxes rents from French property first — but your administrative position has: you are now a third-country national, your social security affiliation must be proved rather than presumed, and every relief depends on paperwork filed on time. This guide explains, step by step, how a British landlord declares French rental income, how to choose between the simplified micro regimes and the actual-expenses regimes, when French social charges are genuinely due, how the France–United Kingdom double tax treaty of 19 June 2008 prevents double taxation, and which remedies exist when the tax office or URSSAF gets it wrong. French legal terms are explained as they appear.

I. How British landlords must declare French rental income after Brexit

A. I let my French property unfurnished — do I use micro-foncier or the actual-expenses regime?

An unfurnished letting (location nue) of a French property produces what French tax law calls revenus fonciers, literally property income. The starting point is Article 14 of the French General Tax Code (Code général des impôts), which provides: “Sous réserve des dispositions de l’article 15 , sont compris dans la catégorie des revenus fonciers, lorsqu’ils ne sont pas inclus dans les bénéfices d’une entreprise industrielle, commerciale ou artisanale, d’une exploitation agricole ou d’une profession non commerciale : 1° Les revenus des propriétés bâties, telles que maisons et usines, ainsi que les revenus : a De l’outillage des établissements industriels attaché au fonds à perpétuelle demeure, dans les conditions indiquées au premier paragraphe de l’article 525 du code civil ou reposant sur des fondations spéciales faisant corps avec l’immeuble ; b De toutes installations commerciales ou industrielles assimilables à des constructions ; c Des bateaux utilisés en un point fixe et aménagés pour l’habitation, le commerce ou l’industrie, même s’ils sont seulement retenus par des amarres. 2° Les revenus des propriétés non bâties de toute nature, y compris ceux des terrains occupés par les carrières, mines et tourbières, les étangs, les salines et marais salants.” In plain English: rents from houses, flats and land fall into the property-income category unless they belong to a commercial business — and that classification decides which tax return to file.

The taxable base starts with gross receipts. Article 29 of the General Tax Code states: “Sous réserve des dispositions des articles 33 ter et 33 quater , le revenu brut des immeubles ou parties d’immeubles donnés en location, est constitué par le montant des recettes brutes perçues par le propriétaire, augmenté du montant des dépenses incombant normalement à ce dernier et mises par les conventions à la charge des locataires.” So you count the rents actually received, plus any landlord expenses passed on to the tenant under the lease, while tenant service charges (charges locatives) that the tenant pays for are ignored. Then Article 28 gives the subtraction: “Le revenu net foncier est égal à la différence entre le montant du revenu brut et le total des charges de la propriété.” Gross minus deductible charges equals net property income — the figure that joins your taxable income.

From there, two regimes compete. The first is the micro-foncier, a simplified regime for small rental portfolios. Article 32 of the General Tax Code provides: “lorsque le montant du revenu brut annuel défini aux articles 29 et 30 n’excède pas 15 000 €, le revenu imposable correspondant est fixé à une somme égale au montant de ce revenu brut diminué d’un abattement de 30 %.” If your annual gross unfurnished rents do not exceed 15,000 euros, the taxable amount is simply 70% of the gross — a flat 30% allowance (abattement) replaces all actual expenses, and you declare the gross directly on the main return. No annex, no receipts schedule. For a British owner with a single modest flat, this is usually the path of least resistance.

The second is the régime réel, the actual-expenses regime, under which you deduct each qualifying charge for its real amount. Article 31 of the General Tax Code lists them: “Les charges de la propriété déductibles pour la détermination du revenu net comprennent : 1° Pour les propriétés urbaines : a) Les dépenses de réparation et d’entretien effectivement supportées par le propriétaire ; a bis) Les primes d’assurance ;” followed by management fees, co-ownership provisions, loan interest on the property loan, and the taxe foncière (the French local property tax paid by owners). Improvement works on dwellings are deductible within limits, while construction, reconstruction or enlargement works are not — the line between deductible repair and non-deductible construction is the single most litigated point in this field, and invoices must describe the works precisely.

Which should you choose? The arithmetic decides. Below roughly 30% of real charges relative to gross rents, micro-foncier wins on simplicity; above that, the réel regime wins on tax. Three practical points matter for British owners. First, the 15,000 euro threshold applies to the whole tax household (foyer fiscal) and all unfurnished rents combined. Second, you may opt for the réel regime even below the threshold — the option binds you for several years, so do not elect it lightly for a year of heavy works unless the following years justify it. Third, an excess of deductible charges over rental receipts creates a déficit foncier (property deficit) that can, within statutory caps and conditions, be set against your other income — a valuable tool the micro regime never offers. Keep every invoice, bank transfer and managing-agent statement for at least the limitation period; in a dispute, the landlord who documents wins, and the landlord who estimates loses.

Brexit changed nothing in these articles, but it changed your file. If you live in France, you declare exactly like a French resident on the same forms (the main 2042 return plus the 2044 annex for the réel regime). If you live in the United Kingdom and your only French income is the rent, you remain taxable in France on that rent and file a non-resident return covering French-source income only. Either way, exchange-rate effects are yours alone: convert each rent at its receipt-date rate, keep a consistent method, and never mix HMRC year-end rates into the French return.

B. I let my French property furnished — why is the profit taxed as a business?

The day you put furniture, bedding, crockery and a equipped kitchen at the tenant’s disposal, French tax law moves your income into a different box. Article 35 of the General Tax Code expressly classes among industrial and commercial profits (bénéfices industriels et commerciaux, universally shortened to BIC): “Personnes qui donnent en location directe ou indirecte des locaux d’habitation meublés ;” — persons who let furnished residential premises directly or indirectly. A furnished flat in Paris, a gîte in Provence, a holiday cottage marketed on a platform: all of these are BIC, not revenus fonciers. The consequences run deep — different return (the professional 2031 annex or the micro-BIC boxes on the main return), different social-charge rules, registration duties, and the Cotisation Foncière des Entreprises (CFE), the local business tax that catches furnished landlords.

Here too a simplified regime coexists with an actual-expenses regime. Article 50-0 of the General Tax Code sets the micro-BIC thresholds, including: “1° bis 15 000 € s’il s’agit d’entreprises dont l’activité principale est de louer directement ou indirectement des meublés de tourisme, au sens du I de l’article L. 324-1-1 du code du tourisme”. A meublé de tourisme — a furnished tourist accommodation, the legal category for most holiday lets — falls under a 15,000 euro ceiling with a flat allowance, while classic long-term furnished lets and other BIC activities benefit from higher ceilings (83,600 euros for services, 203,100 euros for sales and lodging supply). Above the ceiling, or by option, the régime réel BIC applies: you deduct real expenses and, crucially, you may depreciate (amortir) the building, the furniture and the works over their useful lives — something the property-income regime never allows. For a British owner who bought a renovation project, amortisation under the réel BIC can transform the tax picture for a decade.

Three traps catch British furnished landlords every year. First, mixing the boxes: declaring furnished rents on the 2044 property annex is simply wrong and guarantees a correction with late-payment interest. Second, ignoring the tourist-furnished formalities — prior declaration at the town hall (mairie) in many municipalities, registration of the change of use in Paris and other tense zones, the SIRET business number, and since recent reforms the national registration of tourist furnished lets. Fines and back-tax follow the landlord who treats a gîte as an informal arrangement. Third, forgetting that short-term tourist letting in co-ownership buildings or under a lease that forbids it exposes you to civil claims from neighbours and the freeholder alongside the tax risk. Before buying for holiday letting, check the building rules (règlement de copropriété), the municipal authorisation regime, and the planning constraints — the tax optimisation of a purchase that cannot legally be let is worth nothing.

Choosing between micro-BIC and réel BIC follows the same logic as for unfurnished lets, with one addition: simulate amortisation. If the building component alone generates large annual depreciation, the réel regime almost always wins despite the accountant’s fee. Many British owners run this computation once at acquisition and never revisit it; revisit it whenever works, a rate change or a reform of the tourist-furnished ceilings alter the inputs.

II. What a British owner really pays on French rents — and how to challenge it

A. Do I pay French social charges when I already pay UK National Insurance?

Income tax is only half the bill. French rental profits also bear the prélèvements sociaux, the social levies (CSG, CRDS and solidarity levy) collected on capital and property income at an aggregate statutory rate — currently 17.2% — even for landlords who never use the French health system. The legal anchor is Article L. 136-6 of the Social Security Code (Code de la sécurité sociale): “Les personnes physiques fiscalement domiciliées en France au sens de l’article 4 B du code général des impôts sont assujetties à une contribution sur les revenus du patrimoine assise sur le montant net retenu pour l’établissement de l’impôt sur le revenu” and the text expressly lists “a) Des revenus fonciers ;” — property income — while a parallel paragraph catches BIC rental profits. If you are tax-resident in France, the levy applies to your net rental profit as a matter of course.

The harder question is the British owner who lives in the United Kingdom, works there and pays National Insurance there. European Union law long ago established that a person covered by one Member State’s social security system cannot be made to contribute to another’s — the unicité de législation, the single-legislation principle. The Court of Cassation restated it twice on the same day in September 2025. In Cass. civ. 2, 25 September 2025, No. 872 FS-B, appeal F 22-24.634 (Mrs S v URSSAF Franche-Comté), the Second Civil Chamber held that the coordination regulations “consacrent le principe d’unicité de la législation de sécurité sociale, selon lequel la personne à laquelle les règlements s’appliquent n’est soumise qu’à la législation d’un seul État membre, en sorte que celle-ci, affiliée à un régime de sécurité sociale d’un État membre, ne doit pas contribuer au régime de sécurité sociale d’un autre État membre (CJUE, arrêt du 26 février 2015, De Ruyter, C-623-13, point 35).” The sibling decision, Cass. civ. 2, 25 September 2025, No. 873 FS-D, appeal G 22-20.036 (Mr S v URSSAF Franche-Comté), repeats the identical holding: the same regulations “consacrent le principe d’unicité de la législation de sécurité sociale, selon lequel la personne à laquelle les règlements s’appliquent n’est soumise qu’à la législation d’un seul Etat membre, en sorte que celle-ci, affiliée à un régime de sécurité sociale d’un Etat membre, ne doit pas contribuer au régime de sécurité sociale d’un autre Etat membre”. Both appeals by the insured were rejected (REJETTE le pourvoi), but the principle restated is the one British landlords rely on.

What does this mean after Brexit? The United Kingdom is no longer a Member State, so the EU coordination regulations do not apply to you automatically as they once did. Your position now depends on proof. If you hold a valid S1 healthcare certificate, remain compulsorily affiliated to the UK system while posted, or fall under the social-security protocol of the EU–UK Trade and Cooperation Agreement for your situation, you may have grounds to contest French social levies on your rental income — but the burden is on you to produce the certificate and demonstrate that the single-legislation logic covers you. If you are simply a UK resident landlord with no cross-border affiliation certificate, the French administration will treat the levies as due, and a bare reference to “I pay National Insurance” will not move it. Since 2019 the statute itself channels non-residents affiliated elsewhere toward a solidarity levy rather than full CSG/CRDS in defined cases — the exact line depends on your year, your certificates and your residence, which is why generic forum advice on this point is dangerous.

When URSSAF or the tax office bills levies you consider undue, act in order and on time. First, file a written claim (réclamation) with the body that issued the assessment, attaching your UK affiliation evidence, your S1 if you hold one, your residence proofs and the computation you dispute — keep proof of sending. Second, if the reply is negative or never comes within the statutory period, take the dispute to the competent court: the judicial courts for social-levy and URSSAF disputes, the administrative courts for income-tax assessments. Third, never let deadlines drift: French tax claims expire on 31 December of the second year following assessment, and social-body appeals run on short fixed periods stated on each notice. A late claim fails whatever its merits. Interest for late payment and surcharges accrue while you wait, so pay under protest where required to stop the clock, then fight on the principal.

B. Taxed in France and in the United Kingdom — how does the treaty prevent double taxation?

France taxes the rent first. That rule comes from the France–United Kingdom double tax treaty signed on 19 June 2008, whose Article 6 reserves income from immovable property to the State where the property sits: rents from a French flat or house are taxable in France, full stop, whether the landlord lives in London or Lyon. The United Kingdom, as your residence State if you live there, may also tax the same rents under its worldwide-taxation principle — but Article 24 of the treaty obliges it to eliminate the resulting double taxation by granting a foreign tax credit for the French tax paid on that income. You declare twice, you pay once in substance, and each State keeps its paperwork.

In practice the circuit runs as follows. On the French side, you file the French return and pay French income tax plus social levies on the net rental profit as described in Part I. On the UK side, you declare the gross French rents on your Self Assessment return using the foreign property pages, convert euros into pounds at a consistent HMRC-accepted rate, deduct the same categories of expenses HMRC allows — which do not always match the French deductible list — and then claim Foreign Tax Credit Relief for the French income tax attributable to those rents. Keep the French tax assessment (avis d’impôt) as your proof: HMRC routinely asks for it, and the credit cannot exceed the UK tax due on the same income. Where French amortisation under the réel BIC created large French deductions with no UK equivalent, the two computations diverge sharply — that divergence is normal, not an error, provided each return follows its own domestic rules.

Official guidance on both sides confirms the method. The French tax administration’s BOFIP doctrine and the impots.gouv.fr non-resident pages describe how French-source rental income is declared and which annex applies; service-public.fr summarises the declaration of property income for individuals; and gov.uk’s Foreign Tax Credit Relief guidance explains how UK residents relieve French tax on foreign property income. Read the English and French pages together before filing — each administration describes only its own half of the circuit, and misunderstandings almost always come from assuming one return settles both.

Errors cluster in predictable places. Declaring the rent only in the United Kingdom because “HMRC taxes my worldwide income anyway” leaves the French assessment to arrive with penalties. Declaring only in France leaves HMRC interest running. Claiming the UK credit for French social levies as if they were income tax invites refusal: the credit covers income tax, not social charges, and the treaty relief follows that boundary. And misdating income across the two different tax years — France taxes calendar-year receipts, the UK taxes 6 April to 5 April — creates phantom double taxation that is really a timing mismatch; reconcile by receipt date, year by year, and keep a simple spreadsheet mapping each rent to both returns.

If the French office misapplies the treaty — for example by denying a deduction the statute allows, or by assessing social levies from which your certified affiliation exempts you — the remedy is the same disciplined path as for any French tax dispute: administrative claim first, with the treaty articles and your certificates attached, then the administrative court (tribunal administratif) on the tax itself. Name the treaty, quote the article, attach the assessment and the UK return showing the same income: judges apply treaties every day, but only when the claimant puts the text and the facts on the table. Where both States claim the same euro of tax despite the credit mechanism, the treaty’s mutual-agreement procedure between the two administrations exists as a last resort — slow, but designed exactly for genuine double taxation that domestic appeals cannot unwind.

Conclusion

A British landlord succeeds in France by treating the letting as a small French business with French books, even when the owner lives in Britain. Classify the income correctly — property income for unfurnished lets, commercial profit for furnished ones. Choose the regime by arithmetic, not habit: micro-foncier and micro-BIC reward simplicity below their ceilings, while the actual-expenses regimes reward documented charges, works and amortisation above them. Prove your social-security position with certificates rather than assertions, especially since Brexit removed the automatic EU coordination you once enjoyed. Declare in both countries, pay in France first, and claim the UK foreign tax credit with the French assessment in hand. And when an assessment looks wrong, challenge it in writing, with the statute, the treaty and the evidence attached, inside the deadline printed on the notice. Rents are taxable; over-taxation is appealable — the difference lies in the file you keep.

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Telephone consultation within 48 hours with a lawyer of the firm. Call +33 6 46 60 58 22 (Maître Reda Kohen) or write via our contact page. We advise British owners across Paris and Île-de-France on French rental declarations, social charges and double-tax relief.