You moved to France, you pay tax here, and then a brown envelope arrives from HM Revenue and Customs demanding tax on the very same income. Or the sequence runs the other way round: you left France for London, filed your final French return, and the avis d’imposition (the French tax assessment notice) still treats you as a French resident for the whole year. Since Brexit, this double claim has become the routine nightmare of British lives straddling the Channel. Both tax offices sound perfectly sure of themselves, both quote their own domestic law, and you are the one asked to pay twice while they disagree. There is, however, a treaty mechanism designed for exactly this deadlock: the mutual agreement procedure (procédure amiable), in Article 26 of the France-UK double tax convention of 19 June 2008, which obliges the French and British competent authorities to talk to each other and agree on who taxes what, with arbitration if they fail. This article explains, first, why France and the United Kingdom can both claim you at the same time even though a treaty exists, and second, how you force the two administrations to resolve the conflict: the three-year deadline for the mutual agreement claim, the domestic challenges you must run in parallel, and the arbitration that settles the matter when negotiation stalls. Every decisive legal proposition below is taken word for word from the statute, the treaty or the court decision cited beside it.

I. Why France and the United Kingdom can both claim tax from you at the same time

A. When France treats you as living here for tax while HMRC still counts you as UK resident

France decides who is taxable here with its own domestic test, before any treaty is even opened. Article 4 A of the Code général des impôts (the French general tax code) 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 terms, once France regards you as fiscally domiciled here, you are liable to French income tax on your worldwide income. The same article adds the mirror rule: “Celles dont le domicile fiscal est situé hors de France sont passibles de cet impôt en raison de leurs seuls revenus de source française.” If your tax domicile (domicile fiscal) is outside France, France taxes only your French-source income. Everything therefore turns on that one concept, and the code defines it with three alternative criteria. Article 4 B provides: “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 ;” “c. Celles qui ont en France le centre de leurs intérêts économiques.” Meeting any single one of these three tests is enough for the French administration to treat you as a French tax resident. A British family settled in Lyon with children at school here meets the first test through the foyer (the family home); a consultant working three days a week for a Paris client can meet the second; and an investor whose main assets and bank accounts sit in France can meet the third, even while spending months in Kent.

The Conseil d’État (France’s supreme administrative court) has given these words a precise and demanding meaning. In a decision of 21 June 2022, it recalled: “Aux termes de l’article 4 A du code général des impôts : ” 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 “” and, on Article 4 B: “Pour l’application de ces dispositions, le foyer s’entend du lieu où le contribuable habite normalement et a le centre de ses intérêts familiaux, sans qu’il soit tenu compte des séjours effectués temporairement ailleurs en raison des nécessités de la profession ou de circonstances exceptionnelles, et que le lieu du séjour principal du contribuable ne peut déterminer son domicile fiscal que dans l’hypothèse où celui-ci ne dispose pas de foyer.” Two practical lessons follow for a British reader. First, your foyer is where you normally live and keep the centre of your family life, and short professional stays elsewhere do not move it. Second, counting days is only a fallback: the administration looks at the family home first. A year later, in a case about taxpayers domiciled in Monaco disputing French social charges, the same court confirmed the structure of the test, quoting: “Aux termes de l’article 4 B du code général des impôts : ” 1. Sont considérées comme ayant leur domicile fiscal en France au sens de l’article 4 A : / Les personnes qui ont en France leur foyer ou le lieu de leur séjour principal ; / 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 ;”” The administration therefore starts from these domestic criteria and assesses you on worldwide income, without waiting for London’s view. A further illustration comes from a Conseil d’État decision of 16 July 2020 concerning investment income, where the court recorded a taxpayer “dont il est constant qu’il était domicilié fiscalement en France au titre de l’année 2013 en vertu de l’article 4 B du code général des impôts” who had been assessed “à l’issue d’un contrôle sur pièces à l’impôt sur le revenu et aux contributions sociales à raison de profits sur instruments financiers à terme, de dividendes et de gains de cession de valeurs mobilières réalisés lors de cette année”: domestic domicile first, established after a desk audit, with the treaty analysis coming second.

London, meanwhile, applies a completely different machine: the Statutory Residence Test (SRT), with its automatic tests, sufficient-ties test and, crucially for movers, split-year treatment. Under HMRC’s published guidance on split-year treatment, anyone who is UK-resident for a year under the SRT must examine each split-year case, and where all the conditions of one case are met the split-year treatment follows automatically, with no election. The British year of assessment runs from 6 April to 5 April, while the French tax year is the calendar year, so a family moving from Manchester to Montpellier in September can easily be fully UK-resident under one split-year case and fully French-domiciled under Article 4 B for the same months. Neither administration is making an error in its own terms; each applies its domestic clock. That overlap is lawful, and it is precisely the situation the treaty was written to untangle.

The French administration also tells newcomers exactly how the first year is declared, and getting this wrong is the most common trigger of a double bill. The tax office guidance for people arriving in France requires French-source income received before the move to be declared on the non-resident return (form 2042-NR) and all income received after the move on the ordinary resident return (form 2042), with the relevant schedules for rental income (2044) and foreign income (2047). Form 2042-NR is the non-resident return, form 2042 the standard resident return, form 2047 the schedule for income received abroad, and form 2044 the schedule for rental income. A British arrival who declares everything on a single 2042, or who omits the 2047 schedule for UK dividends received after the move, invites both a French correction and continued HMRC taxation of the same items.

B. What the France-UK treaty actually decides for you: one residence and one method for removing double tax

The convention signed on 19 June 2008 between France and the United Kingdom, published in France by Decree No 2010-20 of 7 January 2010 and explained in the official BOFiP commentary on the Franco-British treaty, does not harmonise the two domestic systems. It allocates: where both States claim the same person, the treaty picks a single State of residence, and where one item of income remains taxable in both, it tells the residence State how to eliminate the double charge. Readers with long memories may recall the earlier treaty of 22 May 1968, which the courts applied for decades; the Conseil d’État was still citing “la convention fiscale entre la France et le Royaume-Uni de Grande-Bretagne et d’Irlande du Nord tendant à éviter les doubles impositions et à prévenir l’évasion fiscale en matière d’impôts sur les revenus, signée le 22 mai 1968” in a 2018 decision. That 1968 text has been replaced by the 2008 convention, and it is the 2008 text, with its tie-breaker and its credit method, that now governs every British file.

The tie-breaker sits in Article 4 of the 2008 convention. The first paragraph defines residence by reference to each State’s domestic law, and the second resolves dual residence through a cascade of four tests applied in strict order: first the State where the individual has a permanent home at their disposal, then, where there is such a home in both States, the State of closest personal and economic ties (the centre of vital interests), then the State of habitual presence, then nationality, and finally agreement between the two competent authorities. Note the vocabulary carefully, because it differs from the domestic tests: the treaty speaks of a foyer d’habitation permanent (a permanent home available to you), not the French foyer, and of the centre des intérêts vitaux (the centre of vital interests, where your personal and economic ties are closest). A British national who keeps a flat in Southwark available year-round while renting a house near Bordeaux available year-round has a permanent home in both States, so the answer turns on the centre of vital interests: where the spouse and children live, where the children go to school, where the social life sits, where the main bank accounts and the family doctor are. Only if that balance cannot be struck does habitual presence decide, then nationality, then agreement between the two administrations. A companion article on this site walks through that cascade step by step for British households with a home on each side of the Channel: claimed as tax resident in both France and the UK, the tie-breaker that decides and how to challenge double tax. The present article takes over where that analysis ends: once each side has taken its position and the double bill has actually arrived, how do you force a settlement?

Even after residence is settled, some income stays taxable in both States, and the treaty then imposes a method for removing the second charge. For a French resident with British-source income, Article 24 organises a tax credit (crédit d’impôt) rather than an exemption. For most personal income, the treaty gives France a credit equal to the French tax attributable to the British-taxed income, on condition the French resident was subject to British tax on that income. In practice this means France calculates its tax on the worldwide income, then deducts a credit equal to the French tax attributable to the British-taxed income, capped at the British tax actually and finally borne. The credit can never exceed the French tax on that income, so any surplus British tax is lost, and the mechanism only works if the income is properly declared on form 2047 with proof that the British tax was definitively paid. The mirror rule applies in London: the United Kingdom gives credit for French tax on French-source profits and gains treated as French-source under the treaty. When either administration refuses the credit, misreads the residence outcome, or taxes something the treaty reserves to the other State, the file moves from declaration work to dispute work, and that is where the mutual agreement procedure comes in.

II. How to force France and the United Kingdom to end the double charge

A. File the mutual agreement claim before the three-year clock runs out, and run your domestic challenges in parallel

The mutual agreement procedure is not a court case and not an appeal to either tax office; it is a State-to-State negotiation opened at your request. The French tax administration presents the mutual agreement procedure as a non-judicial route for resolving double taxation or treaty-incompatible charges, running independently of domestic appeals. Two consequences flow from that definition. First, the procedure exists precisely for your situation: taxation by both States that does not comply with the convention, whether the error concerns residence, the credit, or the characterisation of the income. Second, it is independent of domestic appeals, which means it neither replaces them nor is blocked by them; you can and usually must pursue both tracks at once, because the treaty deadlines and the domestic time limits run on separate clocks.

The treaty provision that opens the door is Article 26, headed Procédure amiable. It provides that any resident who considers that the measures of one or both States produce or will produce taxation contrary to the convention may, independently of domestic remedies, submit the case to the competent authority of the State of residence (or of the State of nationality where the non-discrimination article applies). If you present yourself as a French resident, you file with the French competent authority; the published practice designates, for France, the Minister for the Budget or his authorised representative, and directs individual files in practice to the international disputes office of the Direction générale des finances publiques (the French tax administration), bureau SJCF-4B, 64-70 allée de Bercy, 75574 Paris Cedex 12. Your file must identify the measures complained of on each side, the treaty articles breached, the years concerned, and the domestic remedies already lodged, with proof of the tax definitively paid abroad. Then comes the deadline, and it is unforgiving. The same paragraph imposes the time limit: the case must be submitted within three years of the first notification of the offending measure, or within six years of the end of the tax year concerned. The clock starts with the first notice of the offending measure, typically the proposition de rectification (the proposed adjustment notice) or the assessment, not with the end of your domestic appeal. A British taxpayer who waits for years of litigation in one country before approaching the competent authority can find the treaty door already closed, which is why the mutual agreement request should be prepared as soon as the double charge appears, even while domestic remedies continue.

On the French side, the domestic track usually begins with the contradictory adjustment procedure (procédure de rectification contradictoire). The Book of Tax Procedures provides: “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 reply with observations, documents and treaty arguments within the stated time limit, and you may ask for the thirty-day extension the same article organises. The Conseil d’État regularly reviews files that passed through exactly this channel; in a March 2023 decision it recorded the typical sequence: “Par une proposition de rectification du 24 octobre 2016, l’administration lui a notifié, dans le cadre de la procédure de rectification contradictoire, des cotisations supplémentaires d’impôt sur le revenu au titre des années 2013, 2014 et 2015, ainsi que des pénalités correspondantes.” If the administration maintains its position, you contest the assessment through the formal prior claim (réclamation préalable) and then before the administrative court (tribunal administratif), while the mutual agreement file runs its separate course. On the British side, the parallel track means amending the Self Assessment return where still possible, appealing to HMRC within the statutory limits, and if needed to the First-tier Tribunal, because the treaty procedure does not suspend HMRC collection on its own. Keeping both tracks alive preserves every route to a refund: a domestic victory, a negotiated agreement, or arbitration.

Evidence decides these files long before legal argument does, so build the proof pack from day one. For the residence question, assemble the documents that speak the language of the treaty cascade: tenancy agreements or title deeds showing which homes were permanently available and when, utility bills and council tax versus taxe foncière records, school enrolment letters, GP and dentist registrations, travel records and boarding passes establishing habitual presence, employment contracts and client invoices showing where the work was actually done, and bank statements showing where daily spending centred. For the credit question, keep the HMRC assessments and payment receipts proving the British tax was finally borne, the French assessments showing the same income taxed again, and the 2047 schedules as filed. Where the French administration disputes your status after an audit (contrôle sur pièces, a desk audit, or vérification de comptabilité for business income), answer the proposition de rectification point by point with these exhibits rather than with general statements about where you feel resident. The competent authorities negotiate on papers, and a file with dated proof of the permanent home and the centre of vital interests is worth more than any submission about fairness.

B. When the two administrations fail to agree: arbitration, the judge, and getting the overpaid tax back

Once your case is admitted, the French competent authority first examines whether it can solve the problem alone, for example by granting the treaty credit or correcting the residence coding, and if it cannot, it must engage London. The treaty obliges the competent authority that finds the claim well-founded, but cannot resolve it alone, to seek a mutual agreement with the other State’s authority so as to avoid taxation contrary to the convention. And it adds a sentence that matters enormously in practice: the agreement is applied regardless of domestic time limits. An agreement reached in year five can therefore reopen years that domestic time limits would otherwise have closed. The two authorities may also consult to remove double taxation in cases the treaty does not expressly cover: They may also consult together to eliminate double taxation in cases the convention does not expressly cover. But negotiation can stall, particularly where residence turns on the appreciation of family facts, and the 2008 convention does not leave you stranded at that point: it provides for arbitration.

The arbitration clause sits in paragraph 5 of the same Article 26. Where the competent authorities cannot conclude an agreement within two years from the submission of the case to the other authority, and at your request: all unresolved questions arising from the case go to arbitration at the taxpayer’s request. Arbitration is excluded only where a court or administrative tribunal of either State has already ruled on the questions, or where the case falls under the European convention on transfer-pricing arbitration for associated enterprises. The resulting decision binds both States: unless the person concerned rejects the implementing agreement, the arbitration decision binds both contracting States and is applied regardless of domestic time limits. You keep the last word, since you may refuse the implementing agreement, but if you accept it, both France and the United Kingdom must apply it regardless of their domestic limitation periods. For a British family facing two full assessments on the same salary or the same rental profits, that binding effect is the real prize of the procedure: it converts years of parallel disputes into a single enforceable outcome.

Arbitration does not prevent you from asking the judge to decide, and sometimes the courtroom is the faster or the only available route. Before the French administrative courts, the residence fight is argued on Article 4 B as interpreted by the Conseil d’État, and the treaty tie-breaker is then applied to displace the domestic result where the convention so requires; the administration itself is bound by the rule in Article 4 B that domestic residence falls away where the treaty makes you non-resident: “Les personnes qui satisfont à l’un au moins des critères fixés aux a à c du présent 1 ne peuvent toutefois pas être considérées comme ayant leur domicile fiscal en France lorsque, par application des conventions internationales relatives aux doubles impositions, elles ne sont pas regardées comme résidentes de France.” Where the treaty makes you exclusively a United Kingdom resident, France can tax only the income the treaty leaves it, typically French rental income, French business profits of a French permanent establishment, and gains on French property, with the credit machinery withdrawn for the rest. Penalties imposed alongside the disputed principal can also be challenged on their own ground: courts regularly examine whether the administration proved deliberate default (manquement délibéré), and the March 2023 decision mentioned above ended with the court of appeal discharging the penalties while maintaining the principal, a split outcome worth seeking whenever the file shows an honest declaration mistake rather than concealment. On the British side, the First-tier Tribunal decides residence under the SRT and applies the same treaty tie-breaker from the other direction, and a favourable tribunal decision on the facts feeds back into the mutual agreement file, since arbitration is barred once a court has ruled and the competent authorities negotiate in the shadow of decided cases.

Getting the money back is the final stage, and each State has its own refund mechanics once the agreement, the arbitration award or the judgment fixes the outcome. In France, discharge (décharge) of the wrongly assessed tax follows the decision, with late-payment interest (intérêts moratoires) owed to you where the administration held sums it should not have kept; where you paid under enforcement while contesting, the claim for restitution must be pursued without letting domestic limitation periods expire, even while the mutual agreement procedure continues. In the United Kingdom, overpayment relief and the implementation of the agreement through HMRC’s competent-authority unit produce the corresponding repayment with interest under the UK rules. Throughout, keep paying what is enforceable and contesting what is disputed: in France, a formal claim with a request for deferred payment (sursis de paiement) protects you against enforcement while the dispute runs, and in the United Kingdom, time-to-pay arrangements and the statutory appeal posture serve the same protective function. Never simply stop paying on the assumption that the treaty will sort itself out; the treaty sorts out liability, but collection runs on domestic rails until a decision says otherwise.

Conclusion

A double tax bill from Paris and London is not proof that either administration is acting unlawfully; it is the predictable product of two domestic residence machines running on different calendars, meeting a treaty that allocates but does not harmonise. Your path out has four markers. First, identify the true clash: French domicile under Articles 4 A and 4 B against British residence under the Statutory Residence Test, with split-year treatment on one side and the calendar year on the other. Second, apply the treaty’s own order of battle: the Article 4 cascade from permanent home to centre of vital interests to habitual presence to nationality, then the Article 24 credit that caps relief at the French tax on the same income. Third, open the mutual agreement procedure under Article 26 within three years of the first offending notice, with a documented file addressed to the competent authority, while running the French contradictory procedure and the British appeal in parallel so no door closes. Fourth, if the two States cannot agree within two years, request arbitration and let the binding decision, applied regardless of domestic time limits, restore a single taxation. Files won on this terrain share one feature: dated proof of where the home, the family and the economic life actually were, assembled before the first notice arrives. Assemble yours now, diary the three-year deadline the day the first adjustment lands, and make the two tax offices do what the convention obliges them to do: agree.