You live in France, you file in France, and you also receive money from across the Channel: rent from a flat in Manchester, interest from a British bank account, a private pension paid from London, perhaps a salary for remote work done partly in the United Kingdom. One morning an envelope arrives from the Direction générale des finances publiques, the French tax administration, or a message appears in your online tax account. It is a proposition de rectification, a proposal to correct your tax return. The administration says your British income was wrongly declared, wrongly exempted, or wrongly credited, and it now wants additional tax, late interest, and in many cases a 40 per cent surcharge. This note explains, from the texts in force on 1 October 2026, what that letter is, what the first thirty days require of you, how the France United Kingdom double tax treaty protects you, and how a challenge runs from the reply letter to the administrative court. It is written for a British reader and every French term is explained at first use. It does not replace the notice in your hand, and only the court hearing your case decides that case.

The starting position of the French administration is set out on the English pages of impots.gouv.fr, the official site of the French tax authority, which directs French residents receiving foreign source income to the tax treaty signed with the State where the income originates in order to determine whether the income is taxable or exempt in France, whether it must be declared, and which mechanism eliminates any double charge. The same official guidance describes two elimination methods, a credit equal to the tax paid abroad or a credit equal to the French tax relating to the foreign income, and explains that declarable foreign income passes first through return number 2047, whose instructions give the reporting section and any credit. Return 2047 is the annex to the French income tax return on which worldwide income is detailed; return 2042 is the main return. Almost every audit dispute about British income turns on three questions: were you a French resident that year, did the treaty give France the right to tax the item, and did you claim the correct one of those two credit methods. If any link in that chain is wrong, the bill falls, in whole or in part.

Brexit did not rewrite any of this. The treaty between France and the United Kingdom signed in London on 19 June 2008 remains the instrument that allocates taxing rights between the two States, and the Withdrawal Agreement has no tax chapter. What Brexit changed is practical: British nationals are now third country nationals, information about them circulates more visibly between administrations, and inspectors routinely compare the 2047 annex with data received from the United Kingdom under automatic exchange of information. A mismatch between what HM Revenue and Customs knows and what the 2047 shows is the most common trigger of the letter described here. The paragraphs below take the timeline in order: the residence question, the thirty day reply, the computation of the treaty credit with the leading court authority, the surcharges and who must prove what, and the full ladder of challenge, including what changes if you live in Paris or the Ile-de-France region.

I. The audit letter about your British income: whether France may tax you and how to answer within thirty days

A. British income declared in France, or French residence itself: the domicile test and the treaty tie breaker

Before contesting figures, the audit must survive a prior question: were you a French tax resident for the year checked. French domestic law casts a wide net. Article 4 B of the Code général des impôts, the French tax code (official text of 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”. Domicile fiscal means tax home; foyer means the family home; séjour principal means the main place of stay. The same article adds a third domestic criterion, those who have in France the centre of their economic interests: “Celles qui ont en France le centre de leurs intérêts économiques.” Meeting any one of the three domestic tests is enough for the administration to treat you as a French resident, which is why British newcomers who kept a house, a spouse, or most of their investments in France while spending weekdays in London are regularly caught.

Domestic law is not the last word, because the same article contains its own safety valve (official text of Article 4 B): “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.” In plain terms, where the France United Kingdom treaty regards you as a resident of the United Kingdom under its tie breaker, France must stand back even if domestic law pointed to France. The tie breaker examines, in descending order, where you have a permanent home, where your personal and economic relations are closer, meaning the centre of vital interests, where you habitually stay, and your nationality, with any remaining case settled by agreement between the two States. A full walk through that ladder, with worked examples for split lives between London and Paris, is given in the companion note on dual residence, which you should read alongside this one: how the France United Kingdom tie breaker decides dual tax residence. For the audit reply, the practical point is short: if the inspector asserts French residence, answer the residence point first, with dates of presence, the address of the family home, school and medical ties, and the location of the centre of economic interests, because every figure that follows depends on it.

Residence also decides which return you should have filed. A French resident declares worldwide income, and the official guidance quoted above requires British source income to pass through return 2047 before flowing to the main return. The step by step mechanics of that first filing, which boxes carry British wages, rent, interest and pensions, and where the Form 3916 for accounts held abroad fits, are set out in the companion note on the first French return: the first French tax return after the move, forms 2042, 2047 and 3916. In the audit reply, attach the 2047 for the year and show, line by line, that each item of British income was declared somewhere. Many proposed corrections collapse at this stage, because the inspector taxed as omitted income an item that was declared on the wrong line rather than nowhere.

Two traps deserve a paragraph each because they recur in British files. The first is the British bank account that pays a few hundred pounds of interest and feels too small to mention. The reporting framework for accounts held abroad, reflected in Article 1649 A of the Code général des impôts on the declaration of accounts and completed for individuals by the yearly Form 3916 return listing each account held outside France, treats an account missing from Form 3916 as concealed, and concealment extends the recovery period and colours the surcharge discussion examined in Part II. The second trap is the British pension taken partly as a lump sum. Whether the 25 per cent tax free element under British rules survives in France, and which pensions France cannot tax at all, is a treaty question examined in the companion note on pensions: the 25 per cent lump sum France still taxes and the Crown pensions it cannot tax. If the audit targets a lump sum or a Civil Service pension, read that note before drafting the reply, because the treaty article applicable to pensions differs from the one applicable to wages or rent, and the wrong article means the wrong credit.

B. Proposition de rectification received: the thirty day reply, the right to a longer delay, and the motivation test

The letter itself follows a strict contradictory procedure, procédure de rectification contradictoire, meaning a correction procedure in which the taxpayer must be heard before the bill becomes final. Article L. 55 of the Livre des procédures fiscales, the code of tax procedure, states the trigger (official text of Article L. 55): “Sous réserve des dispositions de l’article L. 56, lorsque l’administration des impôts constate une insuffisance, une inexactitude, une omission ou une dissimulation dans les éléments servant de base au calcul des impôts, droits, taxes, redevances ou sommes quelconques dues en vertu du code général des impôts ou de l’article L. 2333-55-2 du code général des collectivités territoriales, les rectifications correspondantes sont effectuées suivant la procédure de rectification contradictoire définie aux articles L. 57 à L. 61 A.” Insuffisance is an understatement, inexactitude an inaccuracy, omission a missing item, dissimulation concealment. Once any of those is alleged, Articles L. 57 to L. 61 A govern, and the centrepiece is the proposal itself.

Article L. 57 (official text of Article L. 57) 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.” The administration sends the taxpayer a proposal which must state its reasons in a way that lets the taxpayer comment or accept. The same article adds a second sentence that practitioners use constantly: “Sur demande du contribuable reçue par l’administration avant l’expiration du délai mentionné à l’article L. 11 , ce délai est prorogé de trente jours.” On the taxpayer’s request received before the expiry of the period mentioned in Article L. 11, the period is extended by thirty days. The base period for observations is thirty days from receipt, and the extension to sixty days is a right, not a favour, provided the request reaches the administration before the first period expires. Send the extension request immediately, by a traceable channel, even before the substance of the reply is ready, because a late reply is treated as tacit acceptance and the procedure moves on without you.

The content of the proposal is controlled as strictly as its timing. The Administrative Court of Appeal of Versailles recalled the wording of Article L. 57 and of Article R. 57-1, under which the proposal must state the nature and reasons for the planned correction and invite the taxpayer to send acceptance or observations within thirty days of receipt. It then drew the consequence in its judgment of 28 May 2020, case 18VE02997: “Il résulte de ces dispositions que, pour être régulière, une proposition de rectification doit comporter, outre la désignation de l’impôt concerné, de l’année d’imposition et de la base des redressements, ceux des motifs sur lesquels l’administration entend se fonder pour justifier les redressements envisagés qui sont nécessaires pour permettre au contribuable de formuler ses observations de manière entièrement utile.” For a proposal to be valid, it must state the tax, the year, the base of the correction, and those of the reasons on which the administration relies that are needed for the taxpayer to comment usefully. A proposal that asserts, without more, that British rental income was omitted, but never says which property, which treaty article, or which credit method was denied, fails this test, and a correction built on an unreasoned proposal can be discharged in full. The official decision is published at CAA Versailles, 28 May 2020, 18VE02997.

In the reply itself, work through four layers in order. First, procedure: was the proposal reasoned, was the thirty day period respected, was the extension granted, and was the reply to your observations itself reasoned, since Article L. 57 (official text of Article L. 57) continues: “Lorsque l’administration rejette les observations du contribuable sa réponse doit également être motivée.” Where the administration rejects the taxpayer’s observations its answer must also be reasoned. Second, residence and treaty characterisation, as in section A. Third, figures: rebuild each item from primary documents, British P60s and SA302s, bank statements, tenancy agreements, pension payslips, with a reconciliation table tying every pound to a line of the 2047. Fourth, penalties: reserve expressly the question of good faith, because interest and surcharges obey different rules, examined now in Part II. Keep the tone factual and complete, because the reply letter frames everything that follows: arguments raised for the first time only before the court are admissible, but arguments documented early settle more files.

II. The amount claimed and the challenge: treaty credit, surcharges, and the ladder from reply to court

A. French tax on British income, treaty credit equal to the French tax, and the 40 per cent surcharge the administration must justify

Where France may tax the British item, the treaty does not exempt it; it neutralises the double charge by a credit. The mechanism lives in Article 24 of the 19 June 2008 treaty, on the elimination of double taxation, and its wording was settled authoritatively by the Conseil d’État, the supreme administrative court, in an advisory opinion of 12 February 2020, case 435907, given on questions referred by the Administrative Tribunal of Cergy Pontoise in a case about British source income. The Conseil d’État quotes the treaty text: “pour les revenus non mentionnés à l’alinéa (ii), au montant de l’impôt français correspondant à ces revenus à condition que le résident de France soit soumis à l’impôt du Royaume-Uni à raison de ces revenus”. For income not listed in subparagraph (ii), the credit equals the amount of the French tax corresponding to that income, provided the French resident is subject to United Kingdom tax on that income. This is the credit equal to the French tax, distinct from the credit equal to the tax paid abroad that applies to other listed categories. The official text of the opinion is published at Conseil d’État, advisory opinion, 12 February 2020, 435907, and the in force treaty itself can be read on the British side at the 2008 United Kingdom France double taxation convention, in force, on GOV.UK and in its consolidated version on the French side at the France United Kingdom treaty as amended, PDF on impots.gouv.fr.

Three holdings of that opinion decide ordinary British files. First, on social charges: the Conseil d’État held that the opening phrase of Article 24 could not be used to deny the credit on French social contributions merely because no equivalent income tax exists in the United Kingdom. The exact holding reads (official text of the opinion): “L’expression en cause ne saurait permettre à la France, s’agissant des résidents de France personnes physiques, de ne pas appliquer le crédit d’impôt prévu à l’alinéa (i) du a) du paragraphe 3 de l’article 24 aux contributions sociales françaises, au motif qu’aucun impôt sur le revenu ou sur un élément du revenu de nature équivalente n’existe au Royaume-Uni.” This matters because British rental income and similar items attract the contribution sociale généralisée and the contribution pour le remboursement de la dette sociale, which the treaty itself lists within French tax. An inspector who allows the income tax credit but refuses the social charges credit on British income is therefore acting against the settled reading, and the reply should say so with the reference.

Second, on the condition of subjection to British tax: the Conseil d’État held that this condition does not require the income to have been effectively taxed: “cette condition n’exige pas que les revenus en cause aient été soumis à une imposition effective.” Third, on what satisfies the condition, the opinion concludes (official text of the opinion): “la condition prévue à l’alinéa (i) du a) du paragraphe 3 de l’article 24 de la convention doit être regardée comme satisfaite s’il est établi par le résident de France qu’il a déclaré les revenus en cause au Royaume-Uni, parce que ces revenus étaient compris dans la base de l’un des impôts énumérés au a) du 1 de l’article 2 de la convention, alors même qu’il n’aurait acquitté dans cet Etat aucun impôt à raison de ces revenus.” For the audit reply, the consequence is concrete: where the inspector denies the credit because the British income fell within the personal allowance and bore no British tax, attach the British return or SA302 showing the income was within the base of income tax, and the credit equal to the French tax must follow. Conversely, income taxable only in the United Kingdom under the treaty distribution rules cannot be taxed in France at all, and must be removed from the base rather than credited.

On top of the principal, the notice adds late interest and, often, a surcharge. Article 1727 of the Code général des impôts provides: “Toute créance de nature fiscale, dont l’établissement ou le recouvrement incombe aux administrations fiscales, qui n’a pas été acquittée dans le délai légal donne lieu au versement d’un intérêt de retard.” Any tax debt not paid by the legal deadline bears late interest, accruing monthly at the statutory rate, and interest applies even to a taxpayer of perfect good faith; it compensates the Treasury for time, it does not punish. Surcharges punish, and they require proof. Article 1729 of the same code sets the scale, with 40 per cent for a deliberate failure: “a. 40 % en cas de manquement délibéré ;” and 80 per cent for fraudulent contrivance: “c. 80 % en cas de manœuvres frauduleuses ou de dissimulation d’une partie du prix stipulé dans un contrat ou en cas d’application de l’article 792 bis .” Manquement délibéré means a deliberate breach; manœuvres frauduleuses means fraudulent contrivance. The official texts are at Article 1727, late interest and Article 1729, surcharges for inaccuracy, with the domestic residence rule at Article 4 B, tax domicile, the contradictory procedure at Article L. 55, contradictory correction procedure, the reasoned proposal at Article L. 57, reasoned proposal and thirty day extension, and the commissions at Article L. 59, referral to the commissions.

Who proves deliberateness is the whole battle over the 40 per cent, and the burden lies on the administration. The Tribunal judiciaire de Paris, the Paris civil court, applied that rule in a judgment of 8 November 2024, case 22/12687, about undeclared foreign holdings, upholding the increase only after finding together a reporting omission, its deliberate character, and an intention to avoid tax. The same judgment observes that a voluntary omission maintained over decades sits uneasily with good faith. Read both points together and the strategy follows: where the British income was declared, even on the wrong line, or where the error flows from a genuine reading of the treaty, such as taking the British personal allowance to mean exemption in France, contest the 40 per cent head on and demand the evidence of intent; where an account truly was hidden, negotiate the principal and the credit rather than a surcharge fight that the file cannot sustain. Spontaneous regularisation before any audit remains valuable for the principal and for interest, but it does not by itself erase a deliberate omission, and the reply should never present regularisation as a legal pardon.

B. Contesting the bill step by step: senior review, the departmental commission, the formal claim, and the court in Paris or elsewhere

If the reply does not persuade the inspector, the procedure offers a ladder, and each rung has its own deadline. The first rung is the quickest: the recours hiérarchique, the senior review, a request that the inspector’s line manager re-examine the file. It is made in writing, recalls the proposal reference, and annexes the documents the inspector is said to have overlooked. It suspends nothing by itself, but in practice collection is often held while it is examined, and a reasoned senior answer sometimes abandons the surcharge while maintaining the principal, which is a result worth taking where the principal is treaty proof.

The second rung is the departmental or national commission. Article L. 59 of the Livre des procédures fiscales (official text of Article L. 59) provides: “Lorsque le désaccord persiste sur les rectifications notifiées, l’administration, si le contribuable le demande, soumet le litige à l’avis soit de la commission des impôts directs et des taxes sur le chiffre d’affaires prévue à l’article 1651 du code général des impôts, soit de la Commission nationale des impôts directs et des taxes sur le chiffre d’affaires prévue à l’article 1651 H du même code, soit de la Commission nationale des taxes aéronautiques prévue à l’article 1651 L bis du même code, soit du comité consultatif prévu à l’article 1653 F du même code, soit de la commission départementale de conciliation prévue à l’article 667 du même code.” Where disagreement persists, the administration, at the taxpayer’s request, submits the dispute for an opinion to the relevant commission, and the same article adds: “Les commissions peuvent également être saisies à l’initiative de l’administration.” The commissions may also be seised at the administration’s initiative. The commission gives an opinion, not a judgment; the administration may depart from it but must reason the departure, and departing from a taxpayer favourable opinion without reasons weakens the later defence before the court. The request must be made in good time after the persistent disagreement is recorded, and the hearing is the first occasion to explain the British documents orally, with translations where needed. For residents of Paris, the competent body is the Paris departmental commission, and the file is handled within the Paris tax directorate; for residents of the inner and outer suburbs, the commission of the department of residence applies, which matters for where to send the request and where to appear.

The third rung is the réclamation, the formal claim against the assessment once the tax is entered for collection. It must be filed before 31 December of the second year following the year of collection, it must state each head of challenge, principal, interest, each surcharge, and it must attach the treaty analysis with the 435907 references where British income is at stake. The administration has six months to answer; silence for six months is an implied rejection, and either an express or an implied rejection opens the court. The fourth rung is the tribunal administratif, the administrative court: two months from the rejection to file, competent for a Paris resident at the Tribunal administratif de Paris and on appeal at the Cour administrative d’appel de Paris. Plead in this order: invalidity of the procedure, starting with the L. 57 motivation test from the Versailles judgment; treaty allocation, asking for discharge of items taxable only in the United Kingdom; credit computation, asking at least for the credit equal to the French tax with the 435907 quotations, including on social charges; and only last the surcharges, demanding proof of deliberateness item by item. Courts may discharge the correction, reduce it, or confirm it, and they decide costs separately; interest runs until payment, so paying the principal under protest while litigating the balance often saves money without conceding the case, provided the payment letter states expressly that every head remains contested.

Two practical warnings close the ladder. First, limitation periods. The administration reassesses within the standard recovery period running from the return, and longer where it could not know the facts, notably where accounts held abroad were never declared on Form 3916. The notice states the years covered; check that each year was still open on the date of the proposal, because a year outside the period falls entirely, with its interest and surcharges. Second, parallel British exposure. Putting the income on the French 2047 does not file it in Britain, and correcting the French position sometimes reveals an unfiled British obligation, or the reverse. The treaty allocates the charge but neither return replaces the other, and correspondence with HM Revenue and Customs, certificates of residence, and the British computation should be kept consistent with the French file, since inconsistent statements across the two files are the administration’s favourite evidence of deliberateness. Where both States claim the same income and neither credit eliminates the residue, the treaty provides a mutual agreement procedure between the two administrations, which the taxpayer may invoke alongside, not instead of, the domestic challenge.

Conclusion

A French audit of British income is a document case decided by a clock. The proposal must be reasoned enough to let you answer usefully, and you must answer within thirty days, extended to sixty on a timely request. Residence comes before figures, the treaty comes before the credit, and the credit equal to the French tax follows wherever the income sat within the base of a listed British tax, even where Britain collected nothing, as the Conseil d’État held on 12 February 2020. Interest compensates for time and applies regardless of intent; the 40 and 80 per cent surcharges punish and require the administration to prove omission, deliberateness, and the intention to escape tax. From the senior review to the departmental commission, the formal claim, and the administrative court, each stage rewards the file that ties every pound to a treaty article, a 2047 line, and a dated document. Prepare that file in the first thirty days, and the bill that arrives in the envelope rarely survives it intact.