You moved to France after Brexit, you file a French tax return every spring, and you thought your UK affairs were settled because HMRC already taxes your British rental income or your pension. Then a letter arrives from the direction générale des finances publiques (the French tax administration): an examen contradictoire de votre situation fiscale personnelle (formal review of your personal tax position), a demande de justifications (request for explanations), or worse, a proposition de rectification (notice of reassessment) adding thousands of euros to your French bill. Your UK bank statements, your rental ledger, sometimes even your HMRC figures are quoted back at you. This is not a mistake and it is not random. Since Brexit, British residents in France are fully third-country nationals for tax cooperation purposes, and automatic exchange of financial information between the United Kingdom and France means the French tax office routinely sees British-source income that never appeared on a French return. The good news is that French tax procedure gives you some of the strongest taxpayer protections in Europe: strict motivation requirements, a 30-day reply window, and judges who cancel reassessments when the administration cuts corners. This guide explains why the French tax office is asking about your UK income, how it found it, how to answer within the deadline, and how the administrative tribunal can wipe the bill out.

I. Why the French Tax Office Is Asking About Your UK Income After Brexit

A. Living in France Makes Your Worldwide Income Taxable in France, Including Every Pound From Britain

The starting point is brutal in its simplicity. Article 4 A of the French General Tax Code (code général des impôts) provides: “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 English: if your tax home (domicile fiscal) is in France, you pay French income tax on all of your income, from everywhere. Your UK rental income, your British State Pension, interest on a UK savings account, dividends from UK shares: all of it belongs on your French return, even if Britain taxes it too. Only people whose tax home is outside France are taxed merely on their French-source income.

And the tax home test is deliberately wide. Article 4 B of the same code states: “1. 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 ; b. Celles qui exercent en France une activité professionnelle, salariée ou non, à moins qu’elles ne justifient que cette activité y est exercée à titre accessoire ;” and it adds a third test, the centre of your economic interests (centre de vos intérêts économiques). Meeting any one of the three is enough. In practice, if your family home is in the Dordogne, if you spend more than six months a year in France, or if your main economic life has shifted to France, you are a French tax resident. Many British newcomers misunderstand the famous 183-day rule: it is only one indicator among others. A retired couple living eleven months a year in their Lot farmhouse with their bank accounts, social life and GP in France is French tax resident even if they still visit children in Kent regularly. Conversely, a British consultant who keeps a flat in London, whose spouse and children stayed in Surrey, and who merely works a three-day week in Paris may remain UK resident. Each file turns on its facts.

Brexit changed nothing in these domestic tests, and that surprises many readers. What Brexit changed is the treaty framework around them: the France–United Kingdom double tax treaty of 19 June 2008 (in force since 2009, published in France by decree) still allocates taxing rights between the two states, but it no longer operates inside the cushion of EU law, EU mutual-assistance directives and freedom-of-movement residence presumptions. British residents are now checked like any other non-EU nationals, and the treaty’s tie-breaker rules decide the hard cases. Where both states claim you, the treaty looks in order at your permanent home, your centre of vital interests, your habitual residence and finally your nationality. The treaty text itself is presented on the British side through the official France: tax treaties collection on gov.uk, and HMRC provides the Form France-Individual for claiming treaty relief.

A practical consequence that British residents often discover too late is the order in which a French judge reasons. The Paris Administrative Court of Appeal recalled the classic rule in a 2023 tax-residence judgment (CAA Paris, 22PA00816): “Si une convention bilatérale conclue en vue d’éviter les doubles impositions peut, en vertu de l’article 55 de la Constitution, conduire à écarter, sur tel ou tel point, la loi fiscale nationale, elle ne peut pas, par elle-même, directement servir de base légale à une décision relative à l’imposition.” In other words, the judge first asks whether French domestic law validly taxes you, and only then whether the treaty blocks that tax. You cannot wave the treaty as a shield without engaging with Articles 4 A and 4 B first. Concretely, if your home and daily life are in France, the reassessment is valid in principle, and the treaty decides only which income France must exempt or give credit for, not whether France may look at you at all. That is why the first reflex when you receive an audit letter should never be that HMRC already taxed the income, but rather a two-step test: am I French tax resident, and if so, did I declare everything the treaty leaves taxable in France. The answer determines your entire defence strategy, because the credit mechanism for British rental income, the exemption-with-progression method for some pensions, and the declaration boxes on forms 2042 and 2047 all flow from it.

Two British profiles come up again and again in our files. The first is the retiree couple who declared their French property and their UK State Pensions but never declared the interest on a Barclays savings pot or the small dividends from a stocks-and-shares ISA, assuming that what HMRC does not tax, France cannot see. France can, and ISAs have no shelter status in France: every pound of interest is declarable. The second is the remote worker or consultant who kept UK self-employment while living near Lyon, invoicing British clients in sterling into a Monzo or Lloyds account, and filing only a UK Self Assessment. If the professional activity is genuinely exercised from the French home, Article 4 B taxes the worldwide professional profit in France, with the treaty then deciding the relief. Both profiles typically surface through the same channel: the bank-account and information trail described in the next section.

B. How the French Tax Office Found Your British Income: Bank Accounts, Form 3916 and Information Exchange With HMRC

Clients always ask the same question: how did they know? The answer is usually a combination of three trails, and understanding them tells you what the tax office can prove and what it merely suspects.

The first trail is your own paperwork. Every French tax resident must declare foreign bank accounts each year on form 3916 (déclaration par un résident d’un compte ouvert hors de France), filed alongside the income return; the official form and its notice are published on impots.gouv.fr, formulaire n°3916. The legal basis is Article 1649 A of the General Tax Code: “Les personnes physiques, les associations, les sociétés n’ayant pas la forme commerciale, domiciliées ou établies en France, sont tenues de déclarer, en même temps que leur déclaration de revenus ou de résultats, les références des comptes ouverts, détenus, utilisés ou clos à l’étranger.” Note the four verbs: opened, held, used or closed. Closing the Lloyds account before moving to the Charente does not erase the duty for the year it was still held, and “used” catches the Revolut or Wise account you merely pass sterling through. The same article adds a presumption with teeth: “Les sommes, titres ou valeurs transférés à l’étranger ou en provenance de l’étranger par l’intermédiaire de comptes non déclarés dans les conditions prévues au deuxième alinéa constituent, sauf preuve contraire, des revenus imposables.” Transfers through an undeclared account are presumed taxable income unless you prove otherwise. That single sentence is the engine of many reassessments against British residents: regular transfers from a UK account to pay the French mortgage, shown on bank statements the administration obtained, become presumed French taxable income until you demonstrate they are capital, a loan, or already-taxed savings. Keep the paper trail that rebuts the presumption: completion statements from a UK house sale, inheritance paperwork, loan agreements, savings histories.

The second trail is automatic exchange of information. Under the OECD Common Reporting Standard, British financial institutions report account balances and income of French residents to HMRC, which forwards them to Paris. Post-Brexit this flow continues: the United Kingdom stayed in the CRS network and the bilateral treaty framework, so your UK interest, dividends and account balances still travel. On top of that, the treaty’s exchange-of-information machinery lets the French administration ask HMRC targeted questions about a named taxpayer, and it lets HMRC spontaneous transmissions land on a French inspector’s desk. Add the French land registry, the fichier des comptes bancaires (national bank-account file), notaires’ filings, and the rental platforms’ reporting duties, and the inspector often opens your file already holding the UK numbers. When the figures on the French return do not match, the computer flags the gap and a human sends the first letter.

The third trail is lifestyle inconsistency, which triggers the heaviest procedure of all: the examen contradictoire de la situation fiscale personnelle (ESFP), the full review of your overall personal tax position. An ESFP compares your declared income with your visible standard of living and your bank movements over several years. A British couple declaring 22,000 euros of pension while running two cars, private health cover, frequent EasyJet bookings and a swimming-pool renovation will be asked to justify the difference. The ESFP is adversarial by design (contradictoire means you are heard throughout), but it is intrusive: years of bank statements, lifestyle questionnaires, coherence tables. It cannot start without strict formalities, which is precisely where many procedures fail, as explained below.

Before panic sets in, sort the letters by seriousness. A demande de renseignements ou de justifications (request for information) is the lightest: the office asks a question and you answer. An avis d’examen de comptabilité or avis de vérification opens a formal audit. A proposition de rectification means the administration has already decided to reassess you and is putting its draft bill to you for observations. Each stage has its own deadline and its own remedy, and confusing them is the costliest mistake British taxpayers make. The next part gives you the response method that works at every stage.

II. How to Answer the Audit and Get the Bill Cancelled

A. Meet the 30-Day Reply Deadline and Force the Administration to Justify Every Pound

French tax procedure runs on written deadlines, and the master deadline is thirty days. Article L. 11 of the Tax Procedure Book (livre des procédures fiscales) provides: “A moins qu’un délai ne soit prévu par le présent livre, le délai accordé aux contribuables pour répondre aux demandes de renseignements, de justifications ou d’éclaircissements et, d’une manière générale, à toute notification émanant d’un agent de l’administration des impôts est fixé à trente jours à compter de la réception de cette notification.” Thirty days from receipt, not from sending. Send your reply by a provable route, keep the proof of posting and the proof of receipt, and diary the date. If the deadline genuinely cannot be met, ask in writing for an extension before it expires and explain why: supporting documents are in the UK, a SAR to your British bank is pending, your accountant needs the HMRC transcript. Extensions are routinely granted once, and a reasoned request filed in time never harms you, while silence always does. Silence after a demande de justifications in an ESFP lets the administration tax you on the basis of its own estimates (taxation d’office), reversing the burden of proof onto you before the judge.

The centrepiece of your defence is the proposition de rectification, and here the law is demanding on the administration, not on you. Article L. 57 of the Tax Procedure Book states: “L’administration adresse au contribuable une proposition de rectification qui doit être motivée de manière à lui permettre de formuler ses observations ou de faire connaître son acceptation.” Motivated so that you can usefully reply or accept. The courts give this sentence real bite. The Paris Administrative Court of Appeal held that “l’administration doit indiquer au contribuable, dans la proposition de rectification, les motifs et le montant des rehaussements envisagés, leur fondement légal et la catégorie de revenus dans laquelle ils sont opérés, ainsi que les années d’imposition concernées.” Grounds, amounts, legal basis, income category, years: all five must appear. The same judgment adds a rule that regularly saves British files: “En cas de motivation par référence, l’administration doit, en principe, annexer les documents auxquels elle se réfère dans la proposition de rectification ou en reprendre la teneur.” When the reassessment refers to outside documents, the administration must in principle attach them or reproduce their content. In British-resident cases the proposition often invokes information received from the British tax authorities or refers to your bank statements without attaching anything. That gap is actionable: write back within thirty days asking for the referenced documents, the computation sheets, the exchange-rate conversions applied to your sterling income, and the treaty article relied upon. A very recent 2026 Paris judgment confirms the current rigour of the courts on this exact article, recalling both the motivation duty and its mirror: “L’administration adresse au contribuable une proposition de rectification qui doit être motivée de manière à lui permettre de formuler ses observations ou de faire connaître son acceptation (…). / Lorsque l’administration rejette les observations du contribuable sa réponse doit également être motivée” (CAA Paris, 2nd chamber, 6 May 2026, 24PA04914). Even the rejection of your observations must itself be reasoned. If the reply letter merely repeats the reassessment without answering your treaty-credit computation or your proof that a transfer was capital, that defective reasoning becomes a ground for discharge before the tribunal.

Formal audits carry one more protection that is frequently violated. Article L. 47 of the Tax Procedure Book provides that a full personal review, a business audit or a desk review of accounts “ne peut être engagé sans que le contribuable en ait été informé par l’envoi ou la remise d’un avis de vérification”, that the notice must state the years under review, and that it must “mentionner expressément, sous peine de nullité de la procédure, que le contribuable a la faculté de se faire assister par un conseil de son choix.” Express mention, on pain of nullity, of your right to be assisted by an adviser of your choice. Check the audit notice the day it arrives: missing years, missing counsel warning, or a review period quietly stretched beyond what was announced can nullify the whole procedure, and nullity of the procedure means discharge of the reassessment regardless of whether the underlying income was taxable. This is the single most valuable page in your file, so keep the envelope, note the delivery date, and photograph every page.

In practical terms, your thirty-day observations letter should do four things in order. First, reserve your position on procedure: list every formal defect you spotted (late notice, missing counsel warning, unattached referenced documents, sterling-to-euro conversions unexplained). Second, answer on residence and treaty qualification: state plainly where your home and economic centre are, which treaty article allocates each item of income, and what credit or exemption you claim, attaching the HMRC Form France-Individual or the UK tax computation where relevant. Third, rebut the Article 1649 A presumption document by document: for each transfer flagged, show its nature with bank history, sale deeds, or gift paperwork. Fourth, close by requesting a recours hiérarchique (hierarchical appeal to the superior) and an appointment with the interlocuteur départemental (departmental mediator) if disagreement persists. These internal appeals are free, suspend nothing by themselves, but often halve the bill before any court is involved, because a fresh pair of eyes sees the computation error the auditor missed.

B. Take the Fight to the Tribunal Before the Time Limits Shut the Door

If the administration confirms the reassessment, you move from discussion to litigation, and the clock becomes your main opponent. The first step is the formal réclamation contentieuse (written claim to the tax office), which you should file as soon as the avis de mise en recouvrement (collection notice) arrives. Once the office answers, or once six months pass without an answer (an implied rejection), you have two months to seise the tribunal administratif (administrative court) of your French home. Miss the two-month window and the bill becomes final even if it was wrong in law. Mark both dates the day the collection notice lands, and file the claim even while settlement talks continue: negotiation does not suspend the limitation period, only a filed claim protects you.

Before the judge, British-resident cases are won on three families of arguments, and you should plead all three rather than betting everything on fairness. The first family is procedure, because a reassessment built on a void procedure falls in its entirety. Rehearse the checklist: was the audit notice regular under Article L. 47, with the years stated and the counsel warning expressed? Was the proposition of reassessment motivated with grounds, amounts, legal basis, income category and years, with referenced documents attached or reproduced, as the Paris court requires? Was the rejection of your observations itself reasoned, as the 2026 Paris judgment insists? Was each thirty-day reply period genuinely honoured? Judges verify these points of their own motion in many configurations, and one missing paragraph in the administration’s paperwork can discharge a six-figure reassessment. That is not a technicality; it is the balance Parliament deliberately struck between the administration’s wide investigative powers and the taxpayer’s right to understand and contest.

The second family is the time bar (prescription / délai de reprise), and it matters enormously for British files because undeclared UK income often spans many years. The basic rule in Article L. 169 of the Tax Procedure Book is: “Pour l’impôt sur le revenu et l’impôt sur les sociétés, le droit de reprise de l’administration des impôts s’exerce jusqu’à la fin de la troisième année qui suit celle au titre de laquelle l’imposition est due.” Three years after the tax year: for 2021 income, recovery normally expires at the end of 2024. But the same article extends the period in classic British-resident situations. It provides that “le droit de reprise de l’administration s’exerce jusqu’à la fin de la dixième année qui suit celle au titre de laquelle l’imposition est due, lorsque le contribuable exerce une activité occulte”, and Article L. 169 further extends recovery to the end of the tenth year where the foreign-account reporting duties were ignored (extension du délai de reprise en cas de manquement aux obligations déclaratives relatives aux comptes étrangers). As a result, a British landlord in the Périgord who never filed form 3916 for the Leeds rental account can face reassessment going back a decade on the linked income, while the neighbour who declared the account every year but merely misreported an amount is usually protected by the three-year bar. The lesson cuts both ways: regularise the 3916 filings now, because each compliant year shortens the administration’s reach, and check every reassessed year against the bar, because inspectors sometimes roll time-barred years into the bill hoping nobody will count.

The third family is substance: treaty qualification, computation and penalties. Walk the judge through each income item against the treaty: UK rental income from a Leeds terrace is taxable in Britain with a French credit; a UK-source government pension for former Crown service follows its own allocation; bank interest is allocated and credited under its article. Attach the HMRC transcripts, the sterling-to-euro conversions at the correct annual rates, and the credit computation on form 2047. For the treaty-credit computation itself, read our companion guide on answering the proposition de rectification and proving treaty relief: how to answer the proposition de rectification, prove your treaty relief and challenge the bill. Challenge the penalties separately: the 40% manquement délibéré (wilful failure) surcharge and the 80% abus de droit or fraud surcharges require proof of intent or scheme, which a first-time British declarant who misunderstood the ISA rules or the 3916 duty will often defeat. Ask the judge in the alternative: annulment first, and failing that, reduction of the base and discharge of the surcharges. Judges grant partial victories frequently, and a bill cut of its penalties and its time-barred years is a transformed bill.

Two practical warnings close this section. First, never ignore a collection notice while the dispute runs: without a formal claim backed by a request for sursis de paiement (deferral of payment with or without guarantees), enforcement, surcharges for late payment and mortgage registrations continue. File the deferral request with the claim. Second, never manufacture evidence. Backdated leases, invented loans and retyped bank statements turn a winnable tax dispute into a criminal file for fraud, and the administration refers cases to the prosecutor precisely when documents look arranged. Win on procedure, time bars and treaty arithmetic, which are honest grounds, and keep every original.

Conclusion

A French tax audit of your British income feels personal, but it follows a standard script: residence under Articles 4 A and 4 B, detection through account reporting and information exchange, a proposition of reassessment you must answer within thirty days, and then the claim and the tribunal. At each step the administration owes you precise paperwork, stated years, attached documents, reasoned replies, and recovery action inside the three-year or, where reporting duties were missed, ten-year window. British residents lose when they stay silent, confuse HMRC’s view with France’s, or let the two-month court deadline slip. They win, in whole or in large part, when they answer in time, force the administration to prove every pound, and plead procedure, time bar and treaty qualification together. If the brown envelope from the finances publiques is on your doormat, treat the thirty days as sacred, gather the UK paperwork now, and get advice before you reply: the first letter you send shapes the entire case.

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Reassessed in France on your UK rental income, pension, savings or transfers, or facing an examen de votre situation fiscale after your move from Britain? Get a telephone consultation within 48 hours with an avocat of the firm. Call +33 6 46 60 58 22 or write via our contact page. We advise British residents throughout France on audits, reassessments and tribunal challenges.