You have just exchanged a rainy London commute for a life in France, and the removal boxes are barely unpacked when a neighbour asks the question that ruins your week: have you filed your French tax declaration yet? For British arrivals after Brexit, the first French tax return feels like a trap. You earned part of the year in the United Kingdom, you may still own a house there, your pension is paid from London, and both countries seem to want a slice of the same income. This guide answers the three questions every newcomer asks our office: from which date France treats you as tax resident, which forms you must file and where each item of British income belongs, and what to do when the tax bill ignores the France-United Kingdom double tax treaty. Every legal statement below is anchored in the French Tax Code, the France-United Kingdom tax convention of 19 June 2008 and the official pages of the French and British administrations, so you can file with confidence and challenge with precision.
I. Am I Really French Tax Resident Now, and From Which Date?
A. When Does France Treat a British Arrival as Domiciled for Tax?
French tax residence has a precise name: the domicile fiscal. Article 4 A of the French Tax Code states that “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, once France regards you as domiciled here for tax purposes, you are taxable on your worldwide income, not merely on your French earnings. That single sentence explains why the residence question dominates your first year: it decides whether your British salary for January to June, your London rental income and your United Kingdom pension all enter the French return. You can read the article in force on Légifrance, article 4 A of the Code général des impôts.
Article 4 B then lists three alternative tests, and meeting any one of them is enough. The text provides that “Les personnes qui ont en France leur foyer ou le lieu de leur séjour principal”, that is, people whose home or principal place of stay is in France, are regarded as domiciled here. A foyer means the place where you habitually live with your family, while the lieu de séjour principal generally means the country where you spend more than 183 days in the year. The second test catches “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”, in other words anyone working in France unless that work is merely ancillary. The third test covers “Celles qui ont en France le centre de leurs intérêts économiques”, those whose centre of economic interests lies in France. The full wording is published on Légifrance, article 4 B of the Code général des impôts.
For a British family that rents a flat in Lyon in September, enrols the children in a French school and keeps only a savings account in London, the answer is straightforward: the foyer moved, so French domicile for tax purposes starts on arrival, and worldwide taxation applies from that date. Income earned before the move while you were still United Kingdom resident stays outside the French charge, but everything received after the arrival date falls into the French return, subject to the treaty relief examined below. The tax administration confirms this logic on its dedicated page for newcomers, je viens ou je reviens en France, impots.gouv.fr, and the general mechanics of the annual return are explained in English on service-public.fr, income tax annual declaration, with first declarations covered on service-public.fr, first income tax declaration.
Difficulties begin when both countries claim you. You arrive in October but keep a house in Kent where your spouse still lives, or you work three days a week in Paris and two in London. Article 4 B itself warns that the French tests fall away where a double tax treaty allocates residence elsewhere. The France-United Kingdom convention of 19 June 2008, signed in London on 19 June 2008 and commented by the French tax administration on BOFiP, France-United Kingdom tax convention. Its article 4 tie-breaker treats the person as resident only of the state where they hold a permanent home and, where homes exist in both states, only of the state of closest personal and economic ties, as explained for the scope of the convention on BOFiP, scope of the convention and residence. The order matters: permanent home first, then centre of vital interests, then habitual stay, then nationality. A British couple that keeps a permanent home available in both countries must therefore document where their personal and economic ties are strongest: children’s schooling, club memberships, bank activity, medical care and the place from which assets are managed. Our related analysis of split households explains the evidence the administration expects, and you can read it here: British couples split between France and the United Kingdom, how to prove tax residence.
Practical advice follows from the texts. Keep a day count from the day you land, retain the lease or completion deed, the school certificates and the travel tickets, and notify both administrations of the move date in writing. If you arrived during 2026, your first French declaration in spring 2027 will cover only the post-arrival period for worldwide income, while French-source income for the whole year remains taxable here. Where the tax office later asserts an earlier residence date, that paper trail is what allows a lawyer to move the starting point and erase months of wrongly taxed income.
B. What Does the United Kingdom Still Claim, and How Does Split-Year Treatment Help?
Leaving the United Kingdom does not switch off British tax on the day your Eurostar departs. The United Kingdom applies its own statutory residence test, and a person who was resident in the year of departure can remain taxable on worldwide income for the whole tax year unless split-year treatment divides that year into a resident part and a non-resident part. The official starting point is gov.uk, United Kingdom residence and tax on foreign income, and the detailed conditions sit in the revenue manual at gov.uk, HMRC manual on split-year treatment, which lists the cases in which leaving the United Kingdom to live abroad triggers the split. The most common route for our clients is the case of starting to have only a home overseas: you cease to have any home in the United Kingdom, you establish a home in France, and your ties to the United Kingdom fall below the threshold for the rest of the year.
Why does this matter for your French declaration? Because without split-year treatment, the same pound of income could be taxed as worldwide income in both countries for overlapping months, leaving you dependent on treaty credit mechanics. With split-year treatment properly claimed, the British charge on non-United Kingdom income stops at departure, which mirrors the French position that worldwide taxation starts at arrival. The two systems then interlock instead of colliding. File the British side correctly: submit form P85 to HM Revenue and Customs when you leave, state the exact departure date, attach the employment or tenancy evidence, and keep the response letter. That letter later proves to the French administration that London taxed only the pre-departure slice, which supports your request for a treaty credit rather than a second full charge.
A frequent mistake is assuming that keeping a small British footprint preserves non-residence in France. It does not work that way round. A spare room at your parents’ house in Manchester rarely creates a French problem, but spending 200 days a year in France while insisting you are still United Kingdom resident fails both countries’ tests at once. Conversely, some newcomers overcorrect and declare themselves French resident from 1 January of the arrival year, offering Paris twelve months of worldwide income when only four were due. The correct method is symmetrical: your United Kingdom residence ends when the statutory test says so, your French domicile begins when article 4 B says so, and the treaty tie-breaker in article 4 resolves any overlap month by month. Where the overlap concerns employment income earned in London before the move, article 15 of the convention confirms that salaries for work physically performed in the United Kingdom remain taxable there, subject to the 183-day and employer exceptions for short cross-border postings. The administration comments these employment rules on BOFiP, France-United Kingdom convention, taxing rules for employment and other income.
One final warning on dates. The British tax year runs from 6 April to 5 April while the French year follows the calendar, so your first French return and your last British return never cover the same twelve months. Build a simple timeline showing employment periods, rental receipts and pension payments against both calendars, and file it with your French return as an annex. Tax inspectors respect coherent chronologies, and judges even more so.
II. How Do I File My First French Declaration Without Paying Twice?
A. Which Forms Do I File, and Where Do My British Pensions, Rents and Accounts Go?
The filing duty itself is not optional. Article 170 of the French Tax Code requires “une déclaration détaillée de ses revenus et bénéfices, de ses charges de famille et des autres éléments nécessaires au calcul de l’impôt sur le revenu”, a detailed declaration of income, family circumstances and every element needed to compute the tax. The same article adds that taxpayers receiving foreign products covered by article 120 “sont tenus, en vue de l’établissement de l’impôt sur le revenu, de comprendre ces revenus dans la déclaration prévue au 1”, meaning your British dividends, interest and similar investment income must appear in that declaration. Read both paragraphs on Légifrance, article 170 of the Code général des impôts. Article 120 defines those foreign investment products, starting with dividends, interest and distributions from companies whose registered office sits abroad, on Légifrance, article 120 of the Code général des impôts. And article 158 states the golden rule of the first return: worldwide and French income merge into one global net income “sans qu’il y ait lieu de distinguer suivant que ces revenus ont leur source en France ou hors de France”, with no distinction between French and foreign sources, on Légifrance, article 158 of the Code général des impôts.
In practice, the newcomer files the standard form 2042 for overall income, plus form 2047 for foreign-source income, plus form 2044 for any rental income from property, plus form 3916 for every bank, life insurance or investment account held outside France. The foreign-account duty has a hard legal base: article 1649 A provides that individuals domiciled in 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”, on Légifrance, article 1649 A of the Code général des impôts. Declare every current account, every savings account and every investment platform, even dormant ones, because the administration receives the same information automatically from London under international exchange agreements and matches it against your 3916. Service-public summarises foreign income reporting for 2026 on service-public.fr, declaration of 2025 income received abroad.
Each British income stream then follows its own treaty lane. Rents from a house you kept in Bristol stay taxable in the United Kingdom first: article 6 of the convention gives the state where immovable property is situated the primary right to tax the income it produces. You therefore declare the gross rent in France on form 2044 and 2047, and France grants relief so the same rent is not taxed twice. Pensions work the opposite way round for most retirees: article 18 reserves pensions for past employment to the state of residence in most cases, so a private pension paid to a French resident is normally taxable only in France, with defined exceptions for government service pensions examined in our dedicated pension guides. Both rules are commented on BOFiP, France-United Kingdom convention, taxing rules for property income and pensions. Dividends and interest from British shares and savings are declared under article 120 and entered on form 2047 with the foreign tax paid, so the credit mechanism can operate. Our guides on the state pension and on private pensions and SIPPs complete this picture: British resident in France, United Kingdom state pension tax and declaration and British resident in France, United Kingdom private pension and SIPP tax.
The relief itself lives in article 24 of the convention, which grants the French resident a credit against French tax for income taxable in the United Kingdom under the treaty, capped at the French tax on that income. The mechanism is detailed on BOFiP, France-United Kingdom convention, elimination of double taxation. Concretely, you report the gross British amount, you tick the treaty-credit boxes on form 2047, you attach the British tax computation or P60, and the French assessment deducts the credit. If the credit is capped below the British tax actually paid, the excess is lost, which is why timing the receipt of a bonus, a lump sum or a property sale around the move date can save thousands.
Two French mechanics surprise newcomers. First, the prélèvement à la source, the pay-as-you-earn system: article 204 A states that taxable salaries, pensions, business profits and rental income “donnent lieu, l’année au cours de laquelle le contribuable en a la disposition ou de leur réalisation, à un prélèvement”, and that “Le prélèvement effectué par le débiteur ou acquitté par le contribuable s’impute sur l’impôt sur le revenu dû par ce dernier au titre de l’année au cours de laquelle il a été effectué. S’il excède l’impôt dû, l’excédent est restitué.” New arrivals with no French payment history typically pay monthly instalments calculated on estimated income, then square the balance the following year, with any overpayment refunded. Full text on Légifrance, article 204 A of the Code général des impôts. Second, the scale itself: article 197 sets the progressive bands applied to each income slice, currently starting above 11 600 euros with rates from 11 to 45 per cent, on Légifrance, article 197 of the Code général des impôts. Apply the family quotient to those bands before comparing with the British charge, because the number of parts can make France cheaper or dearer than the United Kingdom for the same household.
B. The Bill Looks Wrong, How Do I Challenge It and Get the Treaty Applied?
First, read the assessment instead of paying in panic. The avis d’impôt shows the retained residence dates, the income categories and whether the treaty credit was granted. The three classic newcomer errors are a residence start date of 1 January instead of the real arrival month, British rents or pensions coded as purely French income with no credit, and a missing 2047 that pushes foreign income into the wrong boxes. Each has a matching remedy, and each remedy has a deadline, so diary the two-month window printed on the assessment from the day you receive it.
The standard route is the written claim, the réclamation contentieuse, sent to the local tax office with the assessment reference, a clear statement of each correction and copies of the arrival proofs, the British P85 response, the P60 or SA302 computation and the treaty articles invoked. Frame the claim around the texts: article 4 B and the convention tie-breaker for the residence date, articles 6, 15 or 18 for the allocation of each income stream, and article 24 for the credit. Offices correct honest first-year mistakes far more readily when the letter cites the exact provisions and attaches the foreign tax certificates, because the officer can verify rather than investigate. Our walkthrough of the audit procedure shows what happens when the dispute escalates: British resident in France, tax audit and proposition de rectification.
If the administration answers with a reassessment instead, it must follow the adversarial procedure. Article L57 of the tax procedure code provides that “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.” You have thirty days, extendable on request, to reply point by point, and a rejection must itself be reasoned. The provision is published on Légifrance, article L57 of the Livre des procédures fiscales. Use that window to file the missing 2047, to substitute the correct residence date with boarding passes and lease evidence, and to compute the article 24 credit line by line. Silence at this stage is treated as acceptance, so never let the deadline pass unanswered.
When correspondence fails, the administrative court remains open, and judges apply the convention directly. Keep every document for at least six years: passports with stamps, utility contracts in both countries, employer letters with exact posting dates, completion statements for any property sale, pension payslips and every exchange with both revenue authorities. Cases are won on chronology, and the newcomer who built a timeline on arrival day holds a decisive advantage over the administration’s assumptions. Interest for late payment runs while you argue, so consider paying under protest and claiming recovery rather than withholding the whole sum, unless a stay has been formally granted.
Conclusion
Your first French tax declaration rewards method and punishes improvisation. Fix the exact arrival date and prove it, because that date switches worldwide taxation on in France. Close the British year cleanly with split-year treatment and a P85, because a tidy departure certificate makes the French credit almost automatic. File every form the first spring, including the 2047 for foreign income and the 3916 for every British account, because omissions cost more than the tax itself. Allocate each income stream through its treaty article, rents to article 6, pensions to article 18, salaries to article 15, and claim the article 24 credit with the British computations attached. And when the assessment misfires, answer within the deadline with the texts in hand, from article 4 B to article L57. Follow that order and the two tax systems interlock as the treaty intended, instead of taxing the same income twice.
Need a quick opinion on your case
Moving from the United Kingdom to France raises a residence question, a declaration question and often a double tax dispute in the same envelope. Our office offers a telephone consultation within 48 hours with an avocat who handles British newcomers every week. Call +33 6 46 60 58 22 or write through our contact page. We receive clients in Paris and advise across Paris and Île-de-France, in English, from arrival planning to a successful challenge of the assessment.