A British couple can live between France and the United Kingdom without having the same tax residence. One spouse may be resident in France while the other remains resident in the UK, even though they are married, share money, travel between both homes and continue to file a UK Self Assessment return. The difficult question is not whether the couple has a French address or a British address. It is what the facts show for each person, for each relevant tax year, and then what the France–UK Double Taxation Convention does with any conflict.

This distinction matters when a French tax office asks for proof, refuses a French tax residence certificate, excludes a UK spouse from the expected tax treatment, or sends a proposed adjustment covering worldwide income. Brexit did not cancel the convention, but it made documentary discipline more important. This article explains the French domestic tests, the UK Statutory Residence Test, the treaty tie-breaker, the rules for a French couple mixte (mixed couple), the certificates that should not be confused with one another, and the steps for challenging a wrong assessment. It concerns the individual taxpayer settling in France, not the purchase of French property or the creation of a company.

I. How do French and UK rules identify each spouse’s tax residence?

A. What does French law examine before the treaty?

The starting point is the French General Tax Code, the Code général des impôts or CGI. Article 4 A of the CGI draws the basic distinction. It 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 English, a person whose French domicile fiscal (tax domicile) is in France is generally assessed there on worldwide income, subject to the allocation and relief rules in an applicable tax treaty. A person whose tax domicile is outside France is generally taxed in France only on French-source income, again subject to treaty limits.

Article 4 B of the CGI supplies the domestic tests. The current wording refers to people who have in France their home or principal place of stay, who carry on their professional activity there unless it is only ancillary, or who have the centre of their economic interests there. The text says that a person who meets one of those criteria may still not be treated as resident in France where an international convention assigns residence to the other state. This creates a sequence: first identify the position under French domestic law; then apply the treaty if the UK also treats the person as resident.

The French test is personal. It does not follow automatically from the status of the other spouse. A British spouse who works and lives in England may remain UK resident while the other spouse has moved their personal life, work or economic base to France. The reverse can also happen. A marriage certificate, a joint bank account or one shared property may be relevant evidence, but none of them determines both spouses’ residence without examining how each person actually lived and organised their affairs.

The home and the principal stay. Under French practice, the foyer is the place where the taxpayer normally lives and where their personal and family life is centred. It is not simply the address printed on a residence permit. It is also not automatically the property that the taxpayer owns. A long-term rented home, furnished accommodation made available to the taxpayer, or a family home used as the normal base can be relevant. Temporary stays elsewhere for work, holidays or family events do not necessarily move the foyer.

For a couple divided between the two countries, the evidence can be asymmetric. The French spouse may spend most nights in France, receive medical care there, keep day-to-day possessions there and deal with French administration there. The UK spouse may keep a separate home in the UK, work there, maintain a routine there and return to France only for defined periods. The couple’s emotional and financial relationship remains important, but it does not erase the individual factual analysis. The administration may ask where each spouse normally lives rather than where the relationship is based in the abstract.

The Cour administrative d’appel de Paris judgment of 18 June 2026, no. 23PA05246, illustrates why dates and ordinary-life evidence matter. The taxpayer claimed that his domicile had moved to London after acquiring a home there. The court nevertheless examined a Paris lease, the accommodation available in each country, the movement of furniture, utility consumption, the taxpayer’s family life, his work and the income produced by his assets. It recorded the rule: « toute résidence dont une personne dispose de manière durable est pour elle, au sens de la convention, un foyer d’habitation permanent ». The court rejected the claim that the UK evidence, taken with the French evidence, proved the requested result for the relevant period.

This is not a rule that a French home always defeats a move to the UK. It is a warning against relying on a declared intention, a new address or a single transaction date. A spouse who says that France became a secondary base should be able to show when that happened, what changed in daily life, who used each home and how the family’s routine developed afterwards.

Professional activity. A UK employment contract does not settle the French residence question. A British employee can be paid by a UK employer while physically working from France. The place where duties are performed, the pattern of working days, the employer’s instructions, the location of clients, the purpose of travel and the place from which the work is managed can all matter. A director who attends meetings in London but carries out the core work in France needs a more detailed analysis than a payslip or company address can provide.

The same applies to self-employment. Invoices issued to UK clients do not prove that the activity is carried on in the UK. The administration can look at where the work is performed, where the professional premises are, where equipment is kept, and where the taxpayer is physically present when services are supplied. Payroll, permanent-establishment and social-security questions may follow, but they are distinct from the personal residence analysis. They should be mapped together without treating one answer as a substitute for the others.

Economic interests. The French authority may examine income-producing assets, investment management, business interests, rental activity, bank accounts, pension income and the place from which financial decisions are made. A French bank account or a French pension payment is not automatically decisive. Nor is a UK account conclusive evidence of UK residence. The useful question is whether the evidence explains how the taxpayer’s assets and income support their life in the relevant year.

The Conseil d’État decision of 11 December 2009, no. 300733, concerned a couple who claimed to be residents of Great Britain. The court upheld an analysis of their French and London accommodation, their family arrangements, their work and their assets. It accepted that the court below could rely on the fact that « les liens tant économiques que personnels noués par les requérants avec la France étaient plus étroits » than those connecting them with Great Britain. The decision is older and arose under the previous France–UK convention, but the evidential lesson remains useful: a couple’s combined life can be examined closely when the facts point in different directions.

The Conseil d’État decision of 13 May 1983, no. 28831, also demonstrates the importance of the treaty sequence. It explained that the successive residence criteria must be considered in the order set by the applicable convention. A later mutual agreement between administrations cannot replace an earlier criterion that already resolves the person’s status. In a modern France–UK case, that means a taxpayer should address the permanent homes and closer personal and economic relations before asking the authorities to use a last-resort procedure.

The 183-day idea is not a universal safe harbour. French residence cannot be reduced to a number of days copied from a different country’s rule. Principal stay, family home, work and economic interests may each be relevant. A British spouse who spends fewer than 183 days in France can still have a French tax domicile if the factual centre of life is there. Conversely, a person who visits France frequently can remain non-resident if the visits are genuinely temporary and the evidence points to a durable base elsewhere.

French income tax uses the calendar year. The UK tax year normally runs from 6 April to 5 April. A couple must create two calendars: one for each person under French law and one for the UK spouse under UK rules. A move in June can produce a French year containing six months of facts and a UK tax year containing a different period. A day count that looks correct for a UK Self Assessment return may still leave an unexplained period in the French calendar year.

For the wider French assessment procedure and the response to a tax authority’s challenge, see the guide to challenging a French tax residence assessment after Brexit. The present article adds the separate couple question: proving why the two spouses can have different residence positions and how that affects their French declaration.

B. How does the France–UK treaty resolve dual residence and a mixed couple?

The relevant instrument is the convention signed at London on 19 June 2008 and published in France by the Decree no. 2010-20 of 7 January 2010. The UK publishes the same instrument in its official collection of tax treaties in force. Article 4 first defines a resident by reference to domestic liability to tax. If an individual is resident in both countries under those domestic rules, the treaty assigns one residence for treaty purposes through successive tie-breakers.

The order is decisive. The individual is treated as resident only in the state where they have a permanent home. If they have a permanent home in both countries, the next question is the state with the closer personal and economic relations, known as the centre des intérêts vitaux (centre of vital interests). If that cannot be determined, the habitual abode is considered. If the person has a habitual abode in both countries or neither, nationality is considered. If nationality does not resolve the conflict, the competent authorities can address it by agreement under the convention.

Article 4 is not a joint test for the couple. It is applied to the individual. The fact that a spouse and children remain in England may strongly influence the French spouse’s personal connections, but it does not automatically give the French spouse UK treaty residence. The facts may show that the French spouse’s permanent home is in France while the UK spouse’s permanent home is in the UK. If both spouses have durable homes in both states, the centre-of-vital-interests analysis must be carried out separately.

The treaty wording is specific: « si elle dispose d’un foyer d’habitation permanent dans les deux Etats, elle est considérée comme un résident seulement de l’Etat avec lequel ses liens personnels et économiques sont les plus étroits ». A British passport is therefore a late criterion, not a shortcut. Keeping a UK bank account, National Insurance record or electoral registration may help prove an ongoing UK connection, but it does not override a French home and French personal life. The same caution applies to a French residence permit: immigration status and treaty residence answer different legal questions.

The French tax authority’s public guidance confirms that residence is determined for each member of the household. It expressly describes a couple in which one person is in France and the other abroad as a couple mixte. A married couple or a couple bound by a pacte civil de solidarité (PACS, the French civil solidarity pact) can therefore have one French resident and one non-resident for tax purposes. The consequences depend on the legal relationship, the matrimonial property regime and the income that each person receives.

Where the couple is married or PACSed under a community property regime, the French guidance states that the joint declaration includes the worldwide income of the spouse domiciled in France, the French-source income of the spouse abroad that France may tax under the convention, and the relevant dependants domiciled in France. The foreign-source income of the non-resident spouse is not simply added to the French taxable base as though that spouse were French resident. It can, however, be relevant to a request for the average rate where French rules allow it.

Where the spouses are under a separation-of-property regime and are legally separated, the French guidance provides for separate annual assessments and separate online declarations. That result is not produced merely by the fact that one spouse works in the UK. The legal status, the actual separation and the relevant tax facts must be documented. An unmarried couple living together generally does not file one joint French income-tax declaration solely because the partners share a home; the treatment of each person and any children should be checked separately.

Do not confuse tax residence with taxing rights over income. A French resident may receive UK pension, employment, dividend or interest income that the treaty treats in a particular way. A UK resident may still have French-source rental income, employment income or other income that France can tax under domestic law and the treaty. The related France–UK income guide deals with pension classification and declaration. Residence decides which worldwide base is relevant; the treaty article for the particular income decides where that income is taxed and how double taxation is relieved.

Article 164 B of the CGI provides a domestic list of French-source income, including income from French property, French activities and, in specified cases, pensions and annuities paid by a French debtor. The current text of Article 164 B must be read with the applicable France–UK treaty article. A non-resident spouse should not assume that every UK payment is outside France, and a French resident spouse should not assume that every UK payment is taxed twice without credit or exemption.

The convention also contains a mutual agreement mechanism, now found in Article 26 of the 2008 instrument, for a taxpayer who considers that the acts of one or both states produce taxation inconsistent with the convention. That route can be useful in a genuine residence conflict, but it does not suspend the need to answer a French proposed adjustment or to protect a domestic claim deadline. A request to the competent authorities is not a reason to let an ordinary French response period expire.

II. How do you prove the position and challenge a wrong French assessment?

A. Which documents and declarations should a British couple prepare?

Begin with the question being asked. There are at least three different documents that British taxpayers commonly call a “tax residence certificate”. A French resident may need proof for HMRC, a UK bank or another foreign authority. A UK resident may need a UK certificate for a French payer seeking to apply a treaty rate. A French tax office may instead be asking for evidence to decide whether its own assessment is correct. A certificate can support the analysis, but it does not replace the underlying facts and does not automatically bind the other state.

For the French resident proving residence abroad. The French administration publishes form 730-SD as an attestation of French tax residence for presentation to a foreign tax administration. The current impots.gouv.fr page lists a French–English professional version for the 2026 form year. A private individual should verify the precise version and the receiving authority’s requirements before submitting anything. The form is evidence that the French administration certifies; it does not turn a disputed factual situation into a French residence ruling.

For a UK resident claiming French treaty treatment on French-source income. French guidance explains that form 5000 is the residence certificate used for the application of treaty law to income received in France. The official explanation of form 5000 states that the beneficiary completes the first sections, the foreign tax administration completes the residence certification section, and the payer completes its section. The form should be read with the type of income and the France–UK treaty article involved. It is not a universal form proving that the French spouse is resident in France.

For the UK spouse obtaining HMRC proof. HMRC’s certificate-of-residence guidance says that an individual can apply where they are UK resident and there is a double-taxation agreement with the other country. The application requires the treaty, the country, the type of income and the period; a future period cannot be requested. HMRC may also ask for UK day counts, the reason the Statutory Residence Test is satisfied, arrival and departure dates, and the conditions for split-year treatment. If the taxpayer is not entitled to treaty benefits, HMRC states that it will not issue a certificate.

The certificate must match the relevant year. A UK certificate for one UK tax year does not prove French residence or UK treaty residence for every calendar year. It also does not show that the other spouse has the same status. Keep the certificate with the return, the application, the authority’s questions and the explanation of any difference between the French calendar year and the UK tax year.

A persuasive evidence bundle is chronological and indexed. Use a table with four columns: date or period; country; fact; and document. For example, “1 July to 30 September — France — worked from the rented home and attended local medical appointments — employer calendar, utility record and appointment evidence.” This format lets the tax authority see why a document matters. It is more useful than sending unlabelled bank statements or relying on a summary sentence saying that the taxpayer “lived mostly in the UK”.

Separate the documents by the treaty criteria:

• Physical presence: travel records, passport evidence where available, ferry or flight bookings, train records, toll records, calendars and a day-count schedule for both the French calendar year and the UK tax year.
• Homes: leases, title records, insurance, council-tax material, utility consumption, furniture movements, access rights, periods of letting and proof of whether each property was genuinely available for the taxpayer’s own use.
• Personal life: the ordinary residence of the spouse and children, school or university records, medical arrangements, recurring bills, social commitments, caring responsibilities and evidence of where the household’s normal routine took place.
• Work: contracts, employer letters, work calendars, payslips, client meetings, travel instructions, invoices, professional premises and evidence of where duties were physically performed.
• Economic life: bank statements, investment-management mandates, pension statements, rental records, dividend records, business interests and documents showing where financial decisions were made.
• Tax administration: French returns, forms 2042 and 2047 where relevant, UK Self Assessment returns, HMRC correspondence, certificates, notices and explanations of any split-year treatment.

The last category needs care. A return is evidence of what the taxpayer declared; it is not conclusive proof that the declaration was legally correct. The French administration can reassess a position, and the UK can reach a different domestic conclusion. The current Article 170 of the CGI requires an income-tax declaration and states that spouses must jointly sign the household’s overall return in the situations covered by that provision. The filing obligation must therefore be reconciled with the treaty allocation, not used to conceal a spouse’s residence position.

The French public guidance is unusually specific about a mixed couple. If the French spouse’s notice does not apply the average rate that would be more favourable to French-source income of the non-resident spouse, the guidance recommends a formal complaint through the secure messaging service rather than repeating an online correction that may generate another incorrect assessment. A complaint should identify the non-resident spouse, the treaty position, the worldwide income used to calculate the requested average rate, the French-source income actually taxable in France and the documents attached.

When the UK spouse remains in England but visits France every weekend, do not present the visits alone as proof that France is the spouse’s residence. Explain the reason for the visits, the home used, the work performed, the length and regularity of each stay, the spouse’s independent UK home and the treatment of the days under the UK test. When the French spouse lives alone in France during the working week but returns to the UK family home at weekends, do the opposite: explain why the French home is or is not the person’s normal foyer, and support the conclusion with the full year’s pattern.

Evidence should also address contradictory facts. If a UK home was kept but let to an unrelated tenant, attach the lease and possession dates. If a French home was used only by the French spouse, explain that rather than allowing a joint bank statement to imply common occupation. If the taxpayer’s employer required a short French assignment, attach the assignment letter. If the family moved gradually, divide the year into periods instead of forcing one conclusion onto every month.

Finally, use the official sources to state the legal proposition, then use personal documents to prove the facts. The French tax administration’s guidance for residents of France confirms that treaty residence prevails over a conflicting domestic label and that a mixed couple can contain a French resident and a non-resident. Service-Public’s page on who is liable for income tax likewise directs a married or PACSed couple with different situations to verify the applicable obligations. The official guidance is the framework; it is not a substitute for a fact-specific submission.

B. What is the route when France refuses the position or issues an adjustment?

First classify the document. A request for information, a request for supporting documents, a proposition de rectification (proposed tax adjustment), an assessment notice and a decision rejecting a complaint have different effects. Save the document in its original form, record when it was made available in the tax portal and note every deadline. Do not wait for HMRC to finish a certificate application before protecting a French response period.

If a proposed adjustment has been issued, answer the reasoning paragraph by paragraph. Article L57 of the Livre des procédures fiscales (the French Tax Procedure Book, or LPF) requires the administration to send a reasoned proposal so that the taxpayer can respond. The text says the proposal « doit être motivée de manière à lui permettre de formuler ses observations ». Ask the administration to identify the precise facts relied upon if the notice simply says that the couple’s “centre of life” is French without identifying the home, dates, work or economic evidence.

Ordinarily, the proposal provides a 30-day period for observations, and Article L57 allows a further 30 days when the taxpayer makes the request before the original period ends and the extension is available under the procedure. Read the notice itself because special procedures may differ. An extension request should be made through a traceable channel. It should not replace a protective response: state clearly that you dispute the French residence conclusion, set out the treaty sequence and list the evidence that will be supplied.

A strong response has five parts:

1. Scope: identify the taxpayer, the spouse, the tax year or years, the income concerned and the notice being answered.
2. Domestic position: explain the French Article 4 B criteria for each spouse, including the home, principal stay, work and economic interests.
3. UK position: state the result of the Statutory Residence Test for the relevant UK tax year, including days, ties, home, work and any split-year analysis.
4. Treaty position: apply Article 4 to each person in sequence, identifying the permanent home and, where necessary, the closer personal and economic relations.
5. Relief sought: ask for withdrawal of the adjustment, correction of the mixed-couple declaration, treaty relief, the correct average rate or referral of the remaining issue to the appropriate procedure.

If the assessment has already been issued, a réclamation contentieuse (formal tax claim) should be filed promptly through the secure tax portal or the competent service. Article R*196-1 of the LPF states that, for ordinary income-tax claims, the deadline is generally 31 December of the second year following the year in which the tax was assessed or paid, depending on the statutory event. Service-Public’s current deadline guidance gives the same general example: income tax assessed in 2026 can normally be challenged until 31 December 2028. Special rules can apply, so calculate the date from the actual notice and the type of tax.

The complaint should not merely repeat that the couple “lives in two countries”. It should ask for a concrete correction. State which spouse is French resident, which spouse is UK resident for treaty purposes, which income is worldwide in France, which income is French-source for the non-resident spouse, and what double-tax relief is requested. Attach the residence certificates if available, but explain any gap between the certificate’s period and the assessment year.

When the administration rejects or partly rejects the complaint, the decision should be read for the next deadline and the reasons given. A legal dispute about residence is normally taken to the administrative court after the required prior claim. The file should contain the initial declaration, the notice, the proposed adjustment, observations, the administration’s response, the formal claim, its rejection, the evidence index and the treaty analysis. The court will assess the facts and the legal sequence; it will not reconstruct an undocumented year from a late assertion.

Article L59 of the LPF concerns the handling of persistent disagreements on rectifications and the possible involvement of the relevant commission in the situations covered by that article. A pure residence dispute is not automatically solved by sending the file to a commission. The response should identify whether the disagreement concerns a question of law, the factual evidence, the amount of income or a matter that falls within the commission’s statutory field. Do not present a commission referral as a universal alternative to a timely claim and court protection.

The France–UK mutual agreement procedure can be considered where the taxation remains inconsistent with the convention after the domestic steps are protected. The request should describe the double-residence conflict, the domestic conclusions in both states, the treaty tie-breaker and the income affected. It should not be used as a reason to stop replying to the French administration. Domestic assessments, interest and penalties may continue to follow their own procedural timetable while the competent authorities examine a treaty issue.

Late or corrected returns can also have financial consequences. Article 1727 of the CGI provides for interest on a tax debt not paid within the legal period, subject to the exceptions and calculation rules in the article. Article 1728 addresses the failure to file or late filing of a declaration and the applicable increases. A taxpayer who discovers that the wrong spouse was treated as French resident should correct the legal position with an explanation and supporting documents; silence can allow interest or penalties to become part of the dispute.

Three practical errors recur. The first is sending only a UK certificate and assuming that France must accept it without applying Article 4. The second is sending only a French lease and ignoring the UK spouse’s home, days and work. The third is filing a complaint that disputes the tax amount but does not ask the administration to decide the residence question under the treaty. Each error leaves the decision-maker without the chronology needed to distinguish a genuine split household from a temporary travel pattern.

A useful final review asks:

• Have the two spouses been analysed separately under French law and under the UK Statutory Residence Test?
• Have the French and UK tax years been placed on the same chronology?
• Have the available homes been identified for every relevant period?
• Have personal and economic relations been compared rather than reduced to a day count?
• Has Article 4 of the 2008 convention been applied in order?
• Has the correct certificate been requested for the correct country, income and year?
• Has the mixed-couple declaration been checked against the matrimonial or PACS status?
• Have the response, complaint and court deadlines been recorded with proof of submission?

The legal file should then be updated when the facts change. A spouse returning to the UK, a child changing school, a home being let, a new job beginning in France or a pension becoming the household’s main income can alter the evidence for a later year. A certificate or ruling obtained for the first year should not be copied mechanically into the next year. Residence is a year-specific factual and treaty question.

Conclusion

A British couple can legitimately have different tax residences after Brexit. The answer depends on each spouse’s French domestic position, the UK Statutory Residence Test, the homes available, the ordinary pattern of personal life, professional activity and economic interests, and the successive tie-breakers in Article 4 of the France–UK convention. The safest evidence is dated, indexed and capable of explaining why a document proves a particular fact for a particular period.

A French residence certificate, an HMRC certificate and form 5000 serve different purposes. None removes the need to file the correct mixed-couple declaration or to challenge a proposed adjustment and an assessment within the applicable deadlines. If the tax office has treated both spouses as French resident, treated neither as resident, or applied the wrong treaty relief, the response should separate the two people, reconstruct the two tax calendars and ask for a precise correction.

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