You live in Paris now — the children are at the Lycée International, your carte de séjour says it, your landlord and your boulanger agree — but your payslip still comes from London. Every month HM Revenue and Customs takes PAYE off your salary and your bonus, and every autumn the Paris tax office taxes the same money again and invites you to prove why it should not. For British executives, directors and senior staff who kept a City role after settling in France, this double hit on employment income is the most expensive aftershock of Brexit: the salary is taxed at source in Britain, declared worldwide in France, and the Franco-British treaty’s credit mechanism — the device that is supposed to make the French bill disappear — only works if you claim it correctly, document it ruthlessly and defend it when challenged. This guide explains where a London salary is taxed once you live in Paris, how Article 24 of the 19 June 2008 treaty converts British tax into French credit, why the Paris tax offices refuse that credit, and how to fight the refusal from réclamation to the Paris courts, using the very decisions those courts have just handed down. All quotations below are taken word for word from the official texts and judgments linked beside them, checked during this run.

I. When your London salary can still be taxed in Paris and how the treaty credit works

A. I live in Paris but earn in London — which country taxes my salary?

The starting point is French, not British. Once your household (foyer) or main place of stay is in France, you are a French tax resident, and France taxes your worldwide income. Article 4 B of the French Tax Code (Code général des impôts) gives three alternative tests, and one is enough: “Les personnes qui ont en France leur foyer ou le lieu de leur séjour principal” (Article 4 B CGI). Move your family to the 16th arrondissement and test one is met on arrival day, whatever your employer’s letterhead says. The companion test in Article 4 A sets the consequence — worldwide taxation for residents, French-source only for non-residents (Article 4 A CGI) — and Article 79 sweeps your pay into the net: “Les traitements, indemnités, émoluments, salaires, pensions et rentes viagères concourent à la formation du revenu global servant de base à l’impôt sur le revenu” (Article 79 CGI). Fixed salary, annual bonus, benefits in kind, multi-year incentive plan: everything concurs, everything goes on the return.

Residence alone does not settle which country gets to tax the salary first. That is the job of Article 15 of the Franco-British treaty of 19 June 2008, the employment-income article. Its logic, paraphrased, runs in three locks: the salary is taxable only in the employee’s state of residence unless the work is physically done in the other state; even then, the residence state keeps exclusive taxing rights if the employee spends no more than 183 days in the work state in the relevant twelve-month period, is paid by an employer who is not resident there, and does not charge the salary to a permanent establishment there; fail any of those three conditions and both states may tax, with the residence state giving relief. For the Paris-based executive flying to London two or three days a week, the entire dispute almost always collapses into lock one: can you prove, boarding pass by boarding pass, that you were physically present in Great Britain for more than 183 days, or that your London presence stayed under it? Day counts are destiny, and diaries beat memories.

The Paris court of appeal has just shown how mercilessly those day counts and presence facts are tested. In CAA Paris, 9th chamber, 11 April 2025, No. 23PA02576 (CAA Paris, 11 April 2025, No. 23PA02576), a French-resident chief executive claimed treaty credit on his employment income: “M. C… B… a demandé au tribunal administratif de Paris de lui accorder le bénéfice du crédit d’impôt prévu par l’article 24 de la convention fiscale franco-britannique au titre de ses revenus d’emploi des années 2017 et 2018, pour un montant de 2 955 844 euros au titre de l’année 2017 et 8 602 710 euros au titre de l’année 2018.” His thesis was textbook Article 15: “ses revenus d’emploi, comprenant son salaire fixe, les avantages en nature liés, son bonus annuel et son bonus multi-annuel déclaré au titre des années d’imposition en litige, sont imposables en Grande-Bretagne, où il est physiquement présent plus de 183 jours par an depuis le 1er janvier 2016”. Fixed pay, benefits, annual bonus and long-term bonus, all allegedly covered by 183-plus days in Britain. The administration answered with the employer’s geography — a Paris-headquartered company, Paris-based staff, habitual stays and functions exercised in Paris, corporate-governance reports placing management in France — and asked the court to weigh the diary against the reality of where the job was actually run. If your London role is directed from a Paris siège social, supervised Paris teams and documented in board papers signed on avenue Montaigne, expect exactly this treatment: the 183-day count opens the door, but the court walks through the whole house. Where residence itself is genuinely unclear — homes, family and work split down the Channel — read first our guide to how the Franco-British tie-breaker decides whether you are resident in France or the United Kingdom, because Article 15 only helps once residence points at France.

Practical consequences follow before a single figure is filed. First, count days from 1 January with evidence that survives an audit: Eurostar and airline records, hotel invoices, UK entry traces, calendar exports, and a contemporaneous log — reconstructed spreadsheets compiled after the vérificateur calls carry no weight. Second, identify your employer’s residence and your cost centre: paid by a UK-resident employer with the salary borne in London satisfies locks two and three; paid by the Paris entity or recharged to the French branch fails them regardless of days. Third, characterise each pay element now: base salary for London duties, annual bonus for which year’s performance and which country’s work, multi-year awards with vesting conditions tied to which entity’s results — because the administration will recharacterise a London bonus as Paris salary the moment its rationale smells French, and the burden of proving otherwise is yours, as Part II shows.

B. How does Article 24 turn the British tax I paid into French credit?

Once France taxes the salary worldwide and Britain has taxed it at source, Article 24 of the treaty (elimination of double taxation) performs the rescue. For France, the method is a tax credit (crédit d’impôt) equal to the French tax attributable to the British-source income. The Conseil d’État has recited the machinery in the treaty’s own words: “3. En ce qui concerne la France, les doubles impositions sont éliminées de la manière suivante : / a) nonobstant toute autre disposition de la présente Convention, les revenus qui sont imposables ou ne sont imposables qu’au Royaume-Uni conformément aux dispositions de la présente Convention sont pris en compte pour le calcul de l’impôt français” (see CE, 12 February 2020, No. 435907). Note the two halves of that sentence, because newcomers misread both: the British-taxed income must still be included in the French calculation — it preserves the progressive rate applied to your other income — and only then is the credit subtracted. Three corollaries decide real cases. The credit can never exceed the French tax on that income: if Britain taxed the bonus at 45 percent and France would tax it at 30, the 15-point excess is lost, not refunded. Income you never declared in France generates no credit at all, however heavily Britain taxed it. And the credit is computed income by income, so a winning position on base salary does not rescue an undocumented bonus.

That 12 February 2020 decision, No. 435907, is the Conseil d’État’s authoritative reading of this very treaty’s Article 24, and its structure is a warning in itself: the court framed six successive questions on how the credit works — whether the treaty’s override wording lets France deny credit against French social charges (CSG and CRDS) where Britain has no equivalent levy, whether only progressive French taxes qualify for the credit, whether the taxpayer must prove tax actually paid in Britain or merely that the income was declared there, and how each answer cascades into the next. Six questions, each conditional on the last, on a single article: treaty credit is a precision instrument, not a slogan. British executives feel every one of those questions — the March bonus taxed through PAYE, the French social charges levied on the same amount in the autumn assessment, the credit computation that comes back thousands of euros short — and appeals turn on them exactly as the Conseil d’État framed them. Plead the credit with the decision open on the desk, not from memory.

Two filing disciplines decide whether the credit survives contact with the administration. First, declare the British-taxed income on the French return in the year it belongs to, through form 2047 (foreign income annex) feeding the main 2042 return: the Paris court of appeal stated the rule bluntly in the executive’s case — “M. B… n’ayant pas déclaré en France avoir perçu des revenus imposables au Royaume-Uni ouvrant droit à un crédit d’impôt imputable sur l’impôt français sur le fondement de l’article 24 de cette convention, il lui appartient d’établir le bien-fondé de ses prétentions” (CAA Paris, 11 April 2025, No. 23PA02576). Credit claimed for the first time on appeal starts life with that sentence hanging over it. Second, attach the British proof chain to the file from day one: P60 for the departure year, P45, HMRC employment history printout, SA302 or personal tax account calculation showing the income charged in the United Kingdom, the bonus plan rules, and the day-count log. French inspectors cannot query HMRC’s systems; what you cannot document, they disallow. And model social charges separately: CSG/CRDS do not always follow the income-tax credit, and a posted-worker A1 certificate or S1 healthcare certificate changes the answer — the 435907 questions exist precisely because the treaty treats contributions differently from income tax.

Multi-year bonuses deserve a paragraph of their own, because they are where seven-figure disputes are born. A long-term incentive plan vesting in 2025 for performance over 2022–2024, earned while you moved from London to Paris in 2023, raises three questions the administration will ask in order: in which year is it taxable in France, which country’s work does it reward, and which country’s tax does the credit mirror? The executive in 23PA02576 declared multi-annual sums of 3,686,048 euros for 2017 and 13,606,623 euros for 2018 and fought precisely over whether those variable amounts belonged in the treaty’s credit base. Get the vesting-year allocation, the Franco-British work split and the UK charge evidence aligned before filing, and the bonus is one credit computation; file first and reconstruct later, and it becomes three disputes — timing, source and proof — each capable of sinking the others.

II. When the credit is refused and the bill lands in Paris

A. Why does the Paris tax office refuse the treaty credit?

Refusals follow patterns, and the 23PA02576 file exhibits nearly all of them. The first pattern is the undeclared claim: the taxpayer asks the court for credit on income that was never entered on the French return as British-taxed income with a credit claim. The court’s response — the passage quoted above placing the burden on the claimant — is the standard epitaph for such cases, reinforced by the procedural rule the court recalled in the same judgment: “il appartient au contribuable de démontrer le caractère exagéré d’une imposition dont il demande la décharge ou la réduction lorsqu’elle a été établie d’après les bases indiquées dans la déclaration qu’il a lui-même souscrite” (CAA Paris, 11 April 2025, No. 23PA02576). If the assessment was computed from your own return and your return never mentioned British-taxed income, overturning it means proving your own filing wrong — possible, but uphill. The fix costs nothing: complete the 2047 annex every year, line by line, country United Kingdom, tax paid, credit claimed.

The second pattern is failed proof of the 183-day story. Inspectors test presence claims against everything the employer publishes: the Paris registered office described as the place of effective management, Paris-based headcount, your habitual presence in Paris functions, governance reports, even LinkedIn and press interviews placing you at Paris events on days your log claims London. The 23PA02576 court walked through exactly this material before ruling. Counter it with primary evidence, not assertions: travel records beat calendar entries, UK hotel and expense records beat travel records, and third-party traces (building access logs, meeting minutes signed in London) beat everything. Where the role genuinely straddles both cities, consider whether the honest position is a split — part of the salary attributable to French workdays with no credit, part to British workdays with credit — rather than an all-or-nothing 183-day claim that collapses entirely if the count falls short by a week.

The third pattern is recharacterisation: the bonus, the benefits, the long-term award get detached from the British employment the treaty protects and reattached to French duties. Multi-annual sums are the favourite target, as the millions at stake in 23PA02576 show, but benefits in kind (London flat kept on, school fees paid through the UK payroll) and termination payments run close behind. Each element needs its own treaty passport: what it rewards, where the rewarded work was done, where it was taxed. And the fourth pattern is the missing foreign-account declaration sitting next to the credit claim: executives who kept the salary flowing into a sole remaining British current account sometimes forget form 3916, and the file then carries both a credit dispute and a fine dispute. The fine is fixed by Article 1736 of the Tax Code (Article 1736 CGI), in terms the Conseil d’État has recited: “Les infractions aux dispositions du deuxième alinéa de l’article 1649 A et de l’article 1649 A bis sont passibles d’une amende de 1 500 euros par compte ou avance non déclaré” (see CE, 7 February 2018, No. 402034). Our guide to your first French tax return after moving from Britain — forms 2042, 2047 and 3916, penalties and treaty relief covers that declaration duty in full. Paris enforces it without sentiment: two brothers who tried to regularise an undeclared Swiss account and failed lost before the Paris tribunal and lost again on appeal — “Article 1er : Les requêtes de M. D… E… et de M. F… E… sont rejetées” (CAA Paris, 16 December 2022, No. 21PA03929). Never hand the administration a fine dispute as the opening act of your credit dispute.

B. How do I challenge the refusal step by step from Paris?

Every challenge begins with the réclamation, the written complaint to the tax office that must precede any judge. Article L190 of the Book of Tax Procedures (Article L190 LPF) assigns it to the contentious jurisdiction in these terms: “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.” A wrongly refused Article 24 credit is precisely the second branch: the benefit of a right resulting from a legislative provision — the treaty, which has legislative rank in France. File online from your impots.gouv.fr personal space or by recorded-delivery letter to the service des impôts des particuliers (SIP, the local personal-tax office) that issued the assessment, identifying each refused credit line, the treaty article behind it and the HMRC proof attached. The standard deadline runs to 31 December of the second year following the assessment’s recovery notice: for 2025 income assessed in autumn 2026, that is 31 December 2028. The office’s express rejection — or six months of silence, which counts as an implicit rejection — opens the court door. And ask in the same letter for a stay of payment (sursis de paiement) with a guarantee proposal if needed, because France collects first and argues later: without the stay, enforcement against your French bank account (avis à tiers détenteur, the third-party garnishment notice) can proceed while you fight.

If the SIP holds its ground, the Paris-based executive litigates at home: the Paris administrative tribunal (tribunal administratif de Paris) for assessments from a Paris SIP, Montreuil for the inner suburbs, then the Paris administrative court of appeal (cour administrative d’appel de Paris). This is the same judicial pair that produced both flagship decisions in this guide — the tribunal’s 12 April 2023 judgment No. 2103312 appealed in 23PA02576 and its 12 July 2021 judgments in the 21PA03929 fine saga, and the court of appeal’s 2025 and 2022 rulings. Plead the full chain there: residence under Articles 4 A and 4 B, salary within Article 79, the Article 15 tests with the day-count file, the Article 24 credit with CE 435907’s six questions answered for your facts, and the HMRC chain proving the British charge. The Conseil d’État above them hears only points of law (cassation), not a retrial of days and bonuses — win the facts in Paris, because there is no second factual hearing in the Palais-Royal. And remember that even supreme-court victories come with receipts for costs: when the Conseil d’État quashed a residence finding built on property alone, it ordered that “Il y a lieu, dans les circonstances de l’espèce, de mettre à la charge de l’Etat la somme de 3 000 euros à verser à M. et Mme A… au titre des dispositions de l’article L. 761-1 du code de justice administrative” (see CE, 7 October 2020, No. 426124) — 3,000 euros of costs against the State, a useful line in every settlement letter.

Paris offers practical advantages worth using. Your file sits with the Paris regional public-finances directorate (DRFiP Paris) and inspectors who process thousands of international returns: cleaner files move faster, and a réclamation that cites 23PA02576 and 435907 by number signals that the appeal will be competently run — which is itself settlement leverage. Calendar discipline wins cases: file the réclamation online for an unimpeachable timestamp, diary the six-month silence date, and lodge the tribunal appeal within two months of the express or implied rejection. Keep paying or stay the disputed sum, keep the British proof chain updated for each new year while the case runs (later years’ assessments will follow the first one’s logic), and never let a parallel 3916 fine ripen unchallenged alongside the credit case. The system, as the Paris courts demonstrate yearly, rewards the documented executive and taxes the silent one twice.

Conclusion

Your London salary follows you to Paris — French residence under Articles 4 A and 4 B pulls it into worldwide taxation under Article 79 — but the treaty need not let France keep tax Britain already took. Article 15 decides whether Britain may tax the employment income, the 183-day count and the employer’s residence decide whether France must step back, and Article 24 converts the British tax into French credit up to the French tax on the same income, declared first on form 2047 and proved with HMRC paper. When the credit is refused, the path runs from réclamation under Article L190 through the Paris tribunal to the Paris court of appeal that decided 23PA02576 and 21PA03929, with the Conseil d’État’s readings in 435907 and 426124 framing every argument. Count the days, keep the P60s, declare everything, and challenge quickly: the executive who proves the British charge gets taxed once, and only once.