Your first French tax return as a British resident after Brexit is the moment your move becomes real for the French tax office. The year you settle in France, you must tell the Direction générale des finances publiques (the French tax administration) who you are, where you live, and what you earn everywhere in the world — including your UK pension, any rent from a property you kept in Britain, interest from a British bank account, and the very existence of that account. British newcomers regularly get three things wrong: they assume their Withdrawal Agreement residence card settles their tax position, they declare only their French-source income, and they forget the separate form that lists every bank account held abroad. Each of these mistakes carries its own price, from late-filing surcharges to a fixed fine per undeclared account. This guide explains, step by step, how to file your first French return correctly: first, whether France treats you as a tax resident and which three forms you must complete; second, how the France–United Kingdom double tax treaty allocates each type of British income and how to challenge a bill you consider wrong. Every rule below is drawn from official sources — the tax code, the treaty text, the administration’s own guidance pages, and court decisions you can read in full.
I. Are you a French tax resident and what exactly must you declare?
Before any figure goes on any form, one preliminary question decides everything: does France regard you as one of its tax residents? The answer determines whether you declare your worldwide income in France or only your French-source income, which forms you file, and which treaty protections you can claim. British citizens often confuse immigration status with tax status. They are two separate legal worlds.
A. How France decides that a British newcomer is one of its tax residents?
French tax residence — the domicile fiscal — is defined by Article 4 B of the General Tax Code (Code général des impôts): you are a French tax resident if your home (foyer) is in France, if you spend your main period of physical presence there, if you carry on a professional activity there, or if the centre of your economic interests is there. A single one of these four tests is enough. The first test, the foyer, looks at where you habitually live with your family; the courts give it a factual reading, checking school enrolment, utility bills, club memberships and the pattern of your travel, rather than accepting a declaration of intent at face value.
The Cour de cassation applies these tests strictly, and it does so against taxpayers who believed their paperwork abroad protected them. In a widely noted wealth-tax dispute, the court recorded that “Selon l’arrêt attaqué (Reims, 4 décembre 2018), l’administration fiscale a notifié à M. [I] et son épouse, Mme [Y], (M. et Mme [I]) une proposition de rectification de leur impôt de solidarité sur la fortune (ISF), au titre des années 2007 et 2008” after they claimed Swiss tax residence, and it upheld the French reassessment on the facts of their real life rather than on their stated choice of residence (Cour de cassation, commercial chamber, 24 November 2021, appeal no. 19-14.013). The lesson for a British household is direct: keeping a UK address, a British driving licence or even days counted carefully across the Channel does not by itself defeat French tax residence if your family home, your daily life and your economic centre have moved to France.
Three misunderstandings need clearing up at once. First, your Withdrawal Agreement residence card (the WARP card) proves a right to live in France; it neither creates nor excludes tax residence. Second, spending fewer than 183 days in France does not automatically keep you non-resident: the foyer test and the professional-activity test apply regardless of day counts. Third, owning or renting a home in France that you present as a mere holiday home can still tip the balance if the administration shows that your habitual abode is in fact there. Once France treats you as resident, Article 4 A of the General Tax Code (Code général des impôts) makes you liable to French income tax on all of your income, French and foreign alike — which is why the declaration forms for foreign income and foreign accounts matter so much.
The declaration duty itself sits in Article 170 of the General Tax Code (Code général des impôts): every tax household (foyer fiscal) must file an annual return of the previous year’s income within the statutory deadline, online by default through your personal space on impots.gouv.fr. For a first arrival, the practical step that many British newcomers miss is creating that online space early and requesting the paper forms as a fallback: the main return form 2042, its foreign-income supplement form 2047, and the foreign-account statement form 3916. Filing only the 2042 while holding British income or British accounts is the single most common first-year error, and it is the error the administration’s computers are best equipped to detect through automatic exchange of information between the United Kingdom and France.
B. Which three forms carry your British income and your British accounts?
Your first French return as a British resident normally rests on three documents. Form 2042 is the main return: it carries your identity, your household composition, your address on 1 January of the tax year, and your total taxable income by category. Form 2047 is the supplement for income received abroad: the administration describes it exactly as the “declaration des revenus encaisses a l’etranger” (form 2047 on impots.gouv.fr), and it is here — not on the 2042 alone — that you itemise your UK pension, UK rental profits, UK bank interest and UK dividends, country by country, before the totals flow back onto the main return. Form 3916 is the separate statement of bank accounts and life-insurance contracts opened, held, used or closed abroad during the year: every British current account, savings account, ISA-linked cash account and investment platform account must appear on it, even an account that earned nothing and even one you closed mid-year.
The 3916 deserves special attention because its sanction is automatic and per account. The administration’s official guidance states the rule plainly in the tax code itself: undeclared accounts “sont passibles d’une amende de 1 500 € par compte ou avance non déclaré. Toutefois, pour l’infraction aux dispositions du deuxième alinéa de l’article 1649 A, ce montant est porté à 10 000 € par compte non déclaré lorsque l’obligation déclarative concerne un Etat ou un territoire qui n’a pas conclu avec la France une convention d’assistance administrative en vue de lutter contre la fraude et l’évasion fiscales permettant l’accès aux renseignements bancaires” (article 1736 of the General Tax Code (Code général des impôts); see also service-public.gouv.fr, declaring accounts opened abroad). The United Kingdom has a full assistance convention with France, so the standard exposure is 1,500 euros per omitted British account — but three forgotten accounts mean 4,500 euros, and the same guidance adds a steep proportional increase of the duties at stake, which then replaces the fixed fine. Under the declaration duty of Article 1649 A, taxpayers “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”. The legal basis for these fines is Article 1736 of the General Tax Code (Code général des impôts), combined with the declaration duty of Article 1649 A of the General Tax Code (Code général des impôts).
The courts show no indulgence for taxpayers who held foreign accounts and stayed silent. In a February 2025 judgment, the Nancy court set out the typical pattern without ambiguity: “l’administration fiscale a constaté que M. [F] [D] était titulaire de deux comptes bancaires au Luxembourg, qu’il n’avait pas déclarés” — the administration had found two undeclared Luxembourg accounts — and the case then turned on demands for justification of the funds, taxation of unexplained balances at the top gift-tax rate, and the full machinery of reassessment (Tribunal judiciaire de Nancy, 27 February 2025, RG 23/00348). Luxembourg, like the United Kingdom, cooperates with France on tax information; the exchange that exposed those accounts works identically for a Barclays, HSBC or Lloyds account. Declare every account in year one, however small the balance, because the administration learns of it sooner or later and the fine runs per account.
Deadlines and late-filing surcharges complete the first-year picture. Online filing deadlines fall in May and June according to the department of residence — Paris and the inner suburbs traditionally close last — and missing them triggers Late-filing surcharges apply on a rising scale: 10 per cent for simple delay for simple delay, 20 per cent after a formal demand (mise en demeure) goes unanswered, and 40 per cent for a deliberate failure. A related trap concerns the return for the year of arrival itself: you file in France only the income of the period after you became resident, but you must still complete the foreign supplement and the foreign-account statement for that period. Finally, keep every British P60, P45, pension payslip, letting statement and bank certificate for at least the reassessment period — the administration may ask for the origin of any sum, as the Nancy case demonstrates, and a tidy file prepared in year one is your cheapest form of insurance.
II. How is each type of British income taxed and how do you challenge the bill?
Declaring is only half the job; the other half is making sure France taxes each item at the right rate, in the right category, with the right treaty relief — and knowing the procedure when the assessment notice (avis d’imposition) looks wrong. The 2008 France–United Kingdom double tax convention, in force and published by the British government, allocates taxing rights between the two states article by article, and France then applies its own scale, allowances and social levies within the space the treaty leaves it. Errors are frequent on pension classification, on rental-income credits, and on social charges — all three are worth checking line by line.
A. What does the treaty say about your UK pension, your UK rent and your social charges?
Start with the pension most British retirees live on: the regular occupational or personal pension paid for past employment. Article 18 of the 2008 convention reserves ordinary pensions paid for past employment to the state of residence alone, so a British pensioner resident in France is taxable in France on that pension and not in the United Kingdom (2008 UK–France Double Taxation Convention, official GOV.UK text, Articles 18 and 19). In plain terms, if you are resident in France, France alone taxes your ordinary British pension, and the United Kingdom must step back. France then taxes it as pension income with the standard 10 per cent allowance, and the gross amount converted into euros goes through form 2047 onto the 2042. The companion rule that British former public servants must memorise is that Article 19, paragraph 2 keeps the mirror rule for public-service pensions. A Crown pension for British government service therefore stays taxable only in the United Kingdom — unless you are both a French resident and a French national without British nationality, in which case France takes over. Misclassifying a Crown pension as an ordinary pension, or vice versa, is one of the costliest first-year mistakes, and it is worth a dedicated analysis for anyone with mixed service history (see our detailed pension guide, British Pension in France: the 25% Tax-Free Lump Sum France Still Taxes and the Crown Pensions France Cannot Tax).
Rental income from a property kept in Britain follows the opposite logic. Article 6, paragraph 1 of the convention lets the state where the property sits tax the rental income first. The United Kingdom therefore taxes the rent first under its own rules, and France, as your state of residence, includes the same rent in your taxable base but must eliminate the resulting double taxation under Article 24 of the convention — for French residents, by granting a tax credit equal to the French tax attributable to the British rent. The practical consequence is that you declare the gross UK rent on form 2047 with the British tax paid, and you verify on the French assessment that the credit has actually been applied at the right amount. When the credit is missing or short, the French bill is wrong by exactly that sum, and the remedy is a claim, not a shrug.
Social charges — the CSG (contribution sociale généralisée) and CRDS (contribution pour le remboursement de la dette sociale) on investment and property income — are the third item to check, and the one where European law repeatedly proves taxpayers right. The principle, settled after the de Ruyter line of cases and confirmed in later French litigation, is that a person affiliated to the social-security scheme of another state cannot simultaneously be charged French social levies that finance French social-security branches. The Cour de cassation keeps refining this boundary: in a September 2025 decision concerning a person “domiciliée en France et travaillant en Suisse”, who had “demandé le 2 juillet 2019” to the URSSAF the refund of contributions paid since 2015, the court examined precisely which levies finance compulsory French schemes and which fall inside European coordination rules (Cour de cassation, second civil chamber, 25 September 2025, appeal no. 22-24.634). For a British resident holding an S1 certificate of health cover or affiliated in the United Kingdom, the parallel question is live: CSG and CRDS charged on UK rental income or investment gains may be recoverable, and the claim follows the same refund route as any tax dispute. The legal anchor for the levies is Article L. 136-6 of the Social Security Code (Code de la sécurité sociale), and any exemption must be argued against that text with proof of foreign affiliation attached.
A final classification point before turning to remedies: British bank interest and dividends declared on form 2047 enter the French system at the flat rate (prélèvement forfaitaire unique) of 30 per cent including social charges, unless you elect for the progressive scale — an election worth modelling when your overall income is modest. Currency conversion uses the rate at the date of receipt, and the figures must reconcile across forms: the pension on the 2047, the totals on the 2042, the accounts on the 3916. Inconsistency between the three is the fastest route to an automated query, and consistency is entirely within your control.
B. How do you correct a return, claim a refund and take a dispute to court?
French tax procedure gives you a clear ladder: correct, claim, litigate — each rung with its own deadline. Start with correction. A return filed online can be corrected online during the corrective window that reopens in August after the spring campaign, and a paper correction remains possible by letter to your tax office (service des impôts des particuliers). If the assessment notice has already arrived and something is wrong — a missing treaty credit on UK rent, a Crown pension taxed as an ordinary pension, CSG charged despite an S1, a pension allowance forgotten — the remedy is the formal claim (réclamation) governed by Articles L. 190 and R. 190-1 of the Tax Procedure Book (Livre des procédures fiscales). The administration’s own guidance is framed by the contentious-procedure rule: “Les réclamations relatives aux impôts, contributions, droits, taxes, redevances, soultes et pénalités de toute nature, établis ou recouvrés par les agents de l’administration, relèvent de la juridiction contentieuse lorsqu’elles tendent à obtenir 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.” (article L. 190 of the Tax Procedure Book (Livre des procédures fiscales)). The administration’s own guidance sets the practical tone: six months of silence or an unsatisfactory reply opens the door to the court (service-public.gouv.fr, tax claims and legal remedies). For income tax assessed in 2026, the guidance gives the concrete marker of 31 December 2028. File the claim online from your impots.gouv.fr space wherever possible, attach the treaty article, the British payslip or P60, the S1 certificate or the letting accounts, and state the exact sum claimed with its calculation — a claim that merely complains, without figures or documents, is routinely rejected.
Silence has a legal meaning, and it works in your favour. The administration must decide within six months: the administration must decide within six months of receiving the claim, Once that period expires without an answer, the silence counts as an implied rejection (rejet implicite), which opens the door to the administrative court. Filing the claim does not suspend collection — the tax remains payable in the meantime — but you can apply separately for deferred payment (sursis de paiement) with guarantees, so that enforcement is paused while the dispute runs. Interest for late payment (intérêt de retard) accrues mechanically, but it is reduced or cancelled when the claim succeeds, and the court can also award costs. Keep proof of every filing date: the six-month clock and the court deadline both run from dated events, and an undated claim is a procedural gift to the other side.
If the claim fails, the dispute moves to the administrative court (tribunal administratif) under Article R. 199-1 of the Tax Procedure Book (Livre des procédures fiscales): two months from express rejection, or from the expiry of the six-month silence period. For residents of Paris, that is the Paris administrative court; residents of Seine-Saint-Denis, Val-de-Marne and parts of the east go to Montreuil, and Hauts-de-Seine, Val-d’Oise and Yvelines to Cergy-Pontoise — so an address in Boulogne-Billancourt and an address in Saint-Denis do not lead to the same courtroom. The application must identify the tax, the year, the amount, the legal grounds and the evidence; representation by a lawyer is not compulsory at first instance but is strongly advisable once treaty interpretation or European social-security coordination is in play. Appeals go to the administrative court of appeal, and points of law to the Conseil d’État, whose tax chamber decides many treaty cases each year — including, in a September 2026 ruling on cross-border health cover that illustrates how seriously French courts take European coordination arguments, a cassation that sent the parties back for a fuller analysis (Cour de cassation, second civil chamber, 24 September 2026, appeal no. 23-19.562). A parallel lesson comes from declaration litigation itself: the Chambéry court of appeal dealt in September 2026 with a dispute turning on the taxpayer’s declaration duties and the resulting sanctions, a reminder that courts examine who declared what, and when, before reaching the substance (Court of Appeal of Chambéry, 8 September 2026, RG 23/01392).
Two practical warnings close the procedure. First, never ignore a reassessment proposal (proposition de rectification): you have thirty days to respond, extendable on request, and silence at that stage forfeits your best opportunity to stop the surcharge before it is assessed. Second, never pay a professional to “make the file disappear” — the exchange of information between London and Paris means the administration already holds the British figures, and a coherent, documented file with correct treaty references settles faster and cheaper than any shortcut. Done properly, the first return sets the pattern for every later year: residence established once, forms understood once, treaty positions recorded once, and each subsequent spring becomes a routine update rather than a fresh emergency.
Conclusion
Your first French tax return as a British resident stands on three pillars: honest residence analysis under Article 4 B, complete declaration through forms 2042, 2047 and 3916, and correct treaty application to each British income stream. The pension article gives France the taxing right over your ordinary UK pension while reserving Crown pensions to the United Kingdom; the immovable-property article lets Britain tax your UK rent first while obliging France to neutralise the double charge through its credit; and European coordination law may remove French social charges where you are affiliated elsewhere. Each pillar has its sanction — surcharges for late or missing returns, 1,500 euros per undeclared account, full taxation where a credit is forgotten — and each has its remedy: online correction, reasoned claim before 31 December of the second following year, and appeal to the administrative court within two months of rejection or silence. Prepare the file in year one with British certificates, treaty references and dated filings, verify every line of the first assessment notice, and challenge promptly anything that departs from the rules above. The French tax system rewards the organised newcomer and punishes the silent one; after Brexit, organisation is the whole of the art.