You did the sensible thing. After moving to France following Brexit, you drew the tax-free slice of your British pension pot, the quarter that His Majesty’s Revenue and Customs lets you take without British tax within your lump sum allowance, and you transferred the money to your French account. Months later, two letters arrive. Your former pension provider tells you emergency tax was withheld in Britain after all. The French tax office, the fisc, taxes the whole lump sum as a pension at the progressive scale and adds social charges on top. An adviser tells you nothing can be done. That advice is often wrong, but the opposite belief is wrong too: the lump sum is not tax-free in France simply because London charged no tax on it. France taxes its residents on their worldwide income, the double tax treaty between France and the United Kingdom leaves a private pension to the country where you live, and the French Tax Code contains a little-known flat levy of 7.5 per cent after a 10 per cent reduction for retirement benefits paid in capital form, provided the money arrives in one single payment and your contribution history qualifies. Take the money in two instalments and a French appeal court has confirmed that the flat levy is lost, with no excuse accepted even where foreign pension rules pushed you to split the payment. This guide explains, for a British reader living in France, why the lump sum is taxable here, how the treaty lets you recover British tax wrongly withheld, how the 7.5 per cent levy and the quotient averaging mechanism work, which social charges apply and when a health certificate called the S1 removes them, how to declare the payment on the French forms 2042 and 2047, and how to challenge a wrong assessment before the strict deadline expires.

I. Where Is Your UK Pension Lump Sum Taxed When You Become French Resident After Brexit?

A. Why France Taxes the Full Lump Sum Even Though Britain Lets You Take a Quarter Tax-Free

Everything starts with residence, because residence decides which country may tax your pension. Under French law, “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” (Article 4 B of the Code général des impôts, the French Tax Code). The foyer means your home, the place where your family life is centred; the lieu du séjour principal means the place where you spend most of your time, in practice more than 183 days in the year. Once you rent or buy your main home in France, move your family there and organise daily life from France, you are fiscally domiciled in France even if you keep a British bank account, a British passport and strong feelings about the weather in Normandy. From that date, France taxes you on your worldwide income. The Tax Code states the rule plainly for the computation of net overall income: revenues are assessed “sans qu’il y ait lieu de distinguer suivant que ces revenus ont leur source en France ou hors de France” (Article 158 of the Code général des impôts). A pension pot built up in Manchester, Bristol or Edinburgh is therefore inside the French tax net from the day you become French resident, and the year of arrival needs particular care because the exact residence date fixes which country taxes the lump sum.

The British side works differently, which is where the confusion begins. In the United Kingdom, a defined contribution pot, a personal pension or a self-invested personal pension, universally called a SIPP, can normally release part of its value as a cash lump sum. The government guidance explains that part of a workplace or personal pension can be taken free of British tax, and that where some or all of a pension is taken as a lump sum, any amount above the applicable lump sum allowances comes into British Income Tax (GOV.UK, Tax when you get a pension; see also the tax-free guidance). In ordinary language, the first slice up to your allowance, often a quarter of the pot, leaves Britain without British tax, and only the excess bears British Income Tax. Providers also operate emergency tax codes on first payments, so even a slice that should be free can arrive reduced by a withholding that you must later recover. None of this binds France. The British tax-free slice is a British favour granted by British law for British tax purposes. It does not travel across the Channel, and the French tax office owes it no recognition whatsoever.

On the French side, a lump sum that replaces pension rights is treated as pension income, not as a windfall and not as capital gains. The Tax Code provides: “Par exception au a et sous réserve de l’application du 6° bis de l’article 120 ou du II de l’article 163 bis, les prestations de retraite versées sous forme de capital, autres que celles qui sont exonérées en application du 4° bis de l’article 81” follow their own capital-pension regime (Article 158, 5, b quinquies of the Code général des impôts). In plain terms, a retirement benefit paid in capital form, which is the French description of your lump sum, is taxable as pension income under French domestic law. Periodic pensions benefit from a familiar reduction, since “Les pensions et retraites font l’objet d’un abattement de 10 % qui ne peut excéder 4 439 €” (Article 158, 5, a of the Code général des impôts), but a capital payment is channelled toward the specific regimes examined in Part II: the 7.5 per cent flat levy with its own 10 per cent base reduction, or failing that, the progressive scale softened by the quotient. The practical consequence is brutal when the payment is large. A lump sum of 120,000 euros taxed at the progressive scale of income tax, the barème, in a single year stacks the whole amount on top of your other income and pushes much of it into the 30 and 41 per cent bands, before social charges are added. That is why the order of operations matters so much: residence date first, single payment second, express option third, declaration fourth, challenge within the deadline fifth. Readers who receive periodic monthly pension payments rather than a one-off lump sum will find the companion routine in our pillar guide to British private pensions in France: UK Private Pension in France After Brexit: How to Declare It, Recover UK Tax Withheld and Claim Treaty Relief. The present guide covers only the capital lump sum, where the traps and the savings are both larger.

Two preliminary checks therefore come before any arithmetic. First, evidence your residence date with documents a tax inspector respects: the lease or completion deed for your French home, electricity and insurance bills, school enrolment certificates, removal invoices, travel records showing presence, and the date you notified the British authorities of departure. If the lump sum was paid while you were still British resident, Britain keeps the primary right and France can only tax the worldwide income of the arrival year under split-year logic that must be disclosed honestly. If it was paid after you settled in France, France taxes it in full and Britain must step back under the treaty. Second, identify exactly what you received from the provider: a Pension Commencement Lump Sum within allowance, an uncrystallised funds pension lump sum mixing tax-free and taxable parts, a small-pots payment, or a serious-ill-health payment. Each has a different British treatment, yet each arrives in France as a prestation de retraite versée en capital, a retirement benefit paid in capital form, and falls into the French regime described below. Keep the provider’s benefit crystallisation statement, the P45 if one was issued, and every slip showing British withholding, because the reclaim in Britain and the declaration in France both turn on these papers.

B. How the France-United Kingdom Double Tax Treaty Gives France the Taxing Right and Lets You Reclaim British Tax

The treaty that organises all of this is “la convention entre le gouvernement de la République française et le gouvernement du Royaume-Uni de Grande-Bretagne et d’Irlande du Nord en vue d’éviter les doubles impositions et de prévenir l’évasion et la fraude fiscales en matière d’impôts sur le revenu et sur les gains en capital, signée à Londres le 19 juin 2008” (CAA Paris, 10 June 2022, No 21PA01586, citing the treaty). Brexit did not terminate it: double tax treaties are bilateral agreements independent of European Union membership, and this one continues to allocate taxing rights between the two countries exactly as before. Its function is often misunderstood. The treaty does not exempt your pension and does not set the French rate. It distributes the right to tax between the two states so that the same income is not fully taxed twice, and it provides the paperwork that makes the distribution effective. For a British private pension, including a lump sum that replaces pension rights, received by a person who lives in France, the treaty machinery works in one direction: Britain gives up its withholding once French residence is certified, and France taxes the amount under its own domestic rules. The French administration’s published commentary on the treaty covers pensions falling under its pensions article among the relevant items, and it organises the practical relief for residents of France receiving British private pensions through a certified claim form (BOI-INT-CVB-GBR-10-30, French treaty doctrine for the France-United Kingdom convention).

The British starting point is honest about the overlap. The official guidance warns that both the country where a pensioner lives and the United Kingdom may tax the pension, and it points to the double-taxation agreement with the United Kingdom as the remedy against paying twice (GOV.UK, Tax when you live abroad). For France, that agreement exists, so the double charge is a cash-flow problem to be resolved rather than a final burden to be accepted. In practice, British providers frequently deduct emergency tax from a first lump sum paid to someone whose tax code has not caught up with their departure, and the British office keeps the money until a treaty claim proves French residence for the payment year. The French doctrine routes the claim through a France-Individual form for individuals, completed by the beneficiary or a representative and certified by the French tax office (BOI-INT-CVB-GBR-10-30, treaty claim procedure). The form goes to the French tax office of your home, which certifies that you were French resident when the pension was paid; the certified form goes to His Majesty’s Revenue and Customs, which repays the British withholding or authorises future gross payment. The same doctrine adds that the French office keeps its copy to make sure the income stated in the claim is duly taxed in France. That sentence contains the whole bargain in one line: Britain refunds, France taxes.

Three consequences follow for a British reader. First, never accept a British withholding as final without filing the treaty claim. Emergency tax on a lump sum paid after your move is recoverable once France certifies residence, and the claim should be filed as soon as the French position for the payment year is demonstrable, ideally with the French tax assessment or at least the filed return attached. Second, never declare only the net amount received after British withholding on your French return. France taxes the gross lump sum, grants the treaty outcome by taxing it in full, and ignores the British deduction; the French computation then runs on the gross, and the British refund arrives separately. Declaring the net understates French taxable income and exposes you to interest and penalties that dwarf the original saving. Third, keep the two procedures consistent. The residence date on the British reclaim form and the residence date on the French return must match, because both offices now exchange information automatically and a contradiction invites both of them to look closer. State pensions, civil service pensions and government-service pensions obey different treaty articles, with government-service pensions generally remaining taxable by the paying state, so this guide’s reclaim route concerns only private occupational and personal pensions, which is the category containing nearly all defined contribution lump sums.

One warning closes this part. Some advisers still describe the treaty as though it made British pensions tax-free in France, or as though the British tax-free slice inherited French exemption. Both descriptions are wrong and both cost money. The treaty assigns the pension to France; it is the French domestic regimes, the 7.5 per cent levy and the quotient, that soften the bill. The saving is real but it comes from French law applied correctly, not from a treaty exemption that does not exist. With the taxing right settled on France, Part II turns to the only question that now matters: how much French tax, and how to challenge the assessment if the office computed it wrongly.

II. How to Cut the French Bill and Challenge a Wrong Assessment Before the Deadline?

A. The 7.5 Per Cent Flat Levy or the Quotient System: Choosing Expressly Before You File

French law offers the lump sum recipient a precious option. The statute provides: “Les prestations de retraite versées sous forme de capital imposables conformément au b quinquies du 5 de l’article 158 peuvent, sur demande expresse et irrévocable du bénéficiaire, être soumises à un prélèvement au taux de 7,5 % qui libère les revenus auxquels il s’applique de l’impôt sur le revenu. Ce prélèvement est assis sur le montant du capital diminué d’un abattement de 10 %.” (Article 163 bis, II of the Code général des impôts). In ordinary terms, on your express and irrevocable request, the capital pension can bear a flat discharge levy of 7.5 per cent computed on the amount reduced by 10 per cent, and that levy frees the income from further income tax. The prélèvement libératoire, the discharge levy, is the key word: once paid, it settles the income tax on that capital definitively, whatever your marginal band would have charged. On a lump sum of 100,000 euros, the base falls to 90,000 euros and the levy takes 6,750 euros, an effective rate of 6.75 per cent, against tens of thousands at the progressive scale. The option is examined in detail in the administration’s published doctrine for capital pensions (BOI-RSA-PENS-30-10-20, doctrine on the 7.5 per cent levy), which the tax office applies alongside the statute.

The statute attaches two strict conditions, and both must hold on the payment date. It states: “Ce prélèvement est applicable lorsque le versement n’est pas fractionné et que le bénéficiaire justifie que les cotisations versées durant la phase de constitution des droits, y compris le cas échéant par l’employeur, étaient déductibles de son revenu imposable ou étaient afférentes à un revenu exonéré dans l’Etat auquel était attribué le droit d’imposer celui-ci.” (Article 163 bis, II of the Code général des impôts). The first condition is a single payment: the versement, the payment, must not be fractionné, split into instalments. The second looks backward at the building phase: the contributions that funded the rights, including the employer’s share, must have been deductible from taxable income or linked to income exempt in the state that held the taxing right at the time. For a British defined contribution pot, the second condition is usually satisfied without difficulty, because British tax relief on pension contributions is the normal case and the provider’s statements document it. British readers should gather the annual contribution statements, the employer’s scheme booklet confirming relief at source or net-pay funding, and the benefit crystallisation statement, so that the deductibility history can be shown in one bundle if the office asks. Certain capital payments are carved out of the levy altogether, notably benefits from the French retirement savings plan known as the PER, so a transfer that passed through a French plan needs separate analysis before the option is ticked.

The single-payment condition is the trap that destroys most files, and the courts apply it without mercy. In a leading appeal decision, a French resident received a Swiss occupational pension capital in two instalments spread over 2013 and 2014, partly to protect a Swiss tax advantage on voluntary buy-backs. The Lyon appeal court held: “Il résulte ainsi de l’instruction que le versement de l’avoir de vieillesse a été fractionné, notamment au sens des dispositions précitées du II de l’article 163 bis du code général des impôts, lesquelles ne prévoient pas d’exception dans l’hypothèse où le fractionnement proviendrait d’une cause extérieure à la volonté du contribuable.” (CAA Lyon, 28 November 2024, No 22LY01728). No exception exists where the splitting comes from a cause outside the taxpayer’s will: neither foreign pension rules, nor the provider’s default two-tranche mechanics, nor a wish to preserve a foreign tax benefit saves the option. The court added that choosing early payment at a date when the full amount could not be received, in order to keep a Swiss advantage, was itself the taxpayer’s choice, and it ended: “La requête de M. et Mme D… est rejetée.” (CAA Lyon, 28 November 2024, No 22LY01728). The lesson for a British reader is direct. If your provider proposes to pay the lump sum in two tranches, by default or for administrative convenience, refuse in writing and demand one single transfer, keeping the letter as evidence. If drawdown has already started in slices, the levy is gone for the whole capital and no pleading about the provider’s process will bring it back. Sequence the drawdown before acting: confirm French residence, instruct a single payment, then file with the express request.

Where the levy is unavailable, the fallback is the quotient, the averaging mechanism that softens the progressive scale for one-off income. The highest administrative court restates the rule: “Lorsqu’au cours d’une année un contribuable a réalisé un revenu qui par sa nature n’est pas susceptible d’être recueilli annuellement et que le montant de ce revenu exceptionnel dépasse la moyenne des revenus nets d’après lesquels ce contribuable a été soumis à l’impôt sur le revenu au titre des trois dernières années, l’intéressé peut demander que l’impôt correspondant soit calculé en ajoutant le quart du revenu exceptionnel net à son revenu net global imposable et en multipliant par quatre la cotisation supplémentaire ainsi obtenue” (Conseil d’État, 19 March 2018, No 399150). A pension lump sum is by nature incapable of being collected annually, which is precisely the profile the quotient serves, provided its amount exceeds the average net income of the three prior years. The computation adds one quarter of the exceptional income to ordinary income, measures the extra tax, and multiplies that supplement by four, which neutralises the band-stacking that a single-year aggregation would otherwise produce. Neither benefit is automatic. The levy requires the “demande expresse et irrévocable”, the express and irrevocable request, entered where the return invites it. The quotient must be expressly claimed too, with the exceptional amount identified and the three-year average shown. An unclaimed option is treated as a choice of the ordinary scale, and the office will not apply the gentler regime on its own motion. As a rule of thumb, the levy wins for large lump sums of independently comfortable taxpayers, while the quotient can win for modest lump sums received in a low-income year, so both computations should be run before the return is signed and the cheaper one claimed expressly.

B. Declaring on Forms 2042 and 2047, Paying Social Charges and Filing Your Réclamation in Time

Declaration is where strong files are won and weak files are lost, because the French system taxes what you declare and penalises what you omit. The duty is general: “En vue de l’établissement de l’impôt sur le revenu, toute personne imposable audit impôt est tenue de souscrire et de faire parvenir à l’administration une déclaration détaillée de ses revenus et bénéfices” (Article 170 of the Code général des impôts). For a British lump sum, two forms work together. The main return, form 2042, carries the taxable amount and the express option boxes; the annexe 2047 details income collected abroad. The administration describes annex 2047 as the schedule breaking down income collected abroad, with a first section for employment-linked income including pensions (impots.gouv.fr, how income received from abroad is taxed). Report the gross lump sum before British withholding, convert pounds into euros at the rate applicable to the payment date, attach the provider’s statements, tick the 7.5 per cent box with the express request or claim the quotient in the alternative, and keep a complete copy of everything filed. Where the treaty eliminates double taxation through a credit rather than exemption, the same official page explains that tax treaties generally provide a credit reducing French tax (impots.gouv.fr, avoiding double taxation), so the foreign-tax-credit boxes must be completed with the gross declared and the British tax stated separately, never netted off before declaration.

Social charges form the second layer of the bill and depend entirely on your health-cover position. French social levies on replacement income, principally the Contribution Sociale Généralisée (CSG) and the Contribution au Remboursement de la Dette Sociale (CRDS), apply only to persons who are both French tax resident and carried by a French compulsory health scheme. The statute defines the payers as “Les personnes physiques qui sont à la fois considérées comme domiciliées en France pour l’établissement de l’impôt sur le revenu et à la charge, à quelque titre que ce soit, d’un régime obligatoire français d’assurance maladie” (Article L. 136-1 of the Code de la sécurité sociale, the Social Security Code). The phrase à la charge, carried by, does the decisive work. A British pensioner who holds a valid S1 portable document, the certificate by which the United Kingdom remains responsible for healthcare costs, and who is registered with the French health insurance fund, the CPAM (Caisse Primaire d’Assurance Maladie), on that S1 basis, is not carried by the French scheme for the pensions concerned and should not bear CSG and CRDS on the British pension income. By contrast, a British early retiree without an S1 who joined the French universal scheme, the PUMa (Protection Universelle Maladie), is carried by the French scheme and pays the levies, as does any resident affiliated through French employment. The patrimoniale contribution defined at Article L. 136-6 of the Code de la sécurité sociale completes the architecture for capital income, so the classification of each euro must be checked rather than assumed.

The courts have policed the boundary between French levies and European coordination for a decade. The administration itself argued in litigation that “le principe d’unicité de législation sociale, posé par le règlement n°883/2004 de coordination des systèmes de sécurité sociale” governs which single state’s legislation applies (CAA Nancy, 23 July 2020, No 18NC01872), a principle the case law of the Court of Justice known as de Ruyter made decisive for Franco-foreign social charges. The practical message for a British reader is documentary. If you rely on an S1, register it with the CPAM before the lump sum year if possible, obtain the attestation de droits showing S1-based cover, and attach it to the return and to any challenge. If the assessment charges CSG and CRDS despite a valid S1, the error is mechanical and regularly corrected on proof. If you have no S1, verify the rate applied against the pensioners’ scale for the year rather than disputing liability itself, because the liability in that position is genuine. Either way, never ignore the social charges while fighting only the income tax: the two are assessed together and the challenge must state each ground separately so that a partial admission remains possible even if the main ground fails.

When the assessment has already landed and it is wrong, the remedy is the réclamation, the formal claim to the tax office that issued the bill, and the clock is strict. The procedural code provides: “Pour être recevables, les réclamations relatives aux impôts autres que les impôts directs locaux et les taxes annexes à ces impôts, doivent être présentées à l’administration au plus tard le 31 décembre de la deuxième année suivant celle, selon le cas : a) De la mise en recouvrement du rôle ou de la notification d’un avis de mise en recouvrement” (Article R*196-1 of the Livre des procédures fiscales, the Tax Procedure Book). A 2026 assessment is therefore typically challengeable until 31 December 2028, and a 2025 assessment until 31 December 2027, but interest accrues and enforcement continues while you argue, so a request for deferred payment, the sursis de paiement, should accompany the claim. Send the claim by a traceable route, ideally the online messaging of your personal impots.gouv.fr account backed by registered post for large amounts, attach the provider’s payment proofs, the residence evidence, the contribution history and the S1 attestation where relevant, and state each legal ground in numbered order: treaty allocation with residence proof and British reclaim reference, levy with single-payment proof and contribution history, quotient in the alternative with the three-year computation, social charges with the S1 attestation. Ask expressly for discharge of the dischargeable parts, reduction in the alternative, and interest relief. If the office rejects the claim expressly or stays silent for six months, the dispute moves to the administrative court, the tribunal administratif, where the same bundle, completed by the assessment notices and the claim receipts, forms the case file.

Conclusion

A British pension lump sum drawn as a French resident is taxable in France, usually at the progressive scale unless you secured the 7.5 per cent flat levy with a single payment and a qualifying contribution history, with the quotient as the fallback and social charges as a second layer governed by your S1 position. The treaty protects you against genuine double taxation by assigning the private pension to France, which means the practical fight is about the French rate and the French base, plus recovering whatever Britain withheld in error through the certified France-Individual form. Sequence the operation correctly: evidence your residence date, draw the capital once, request the levy expressly, declare the gross on forms 2042 and 2047, verify the social charges against your health-cover documents, and reclaim in Britain without delay. If the assessment has already arrived, check the 31 December of the second following year before assuming the file is closed, because most of these cases remain winnable inside that window with the right documents presented in the right order.

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