You came to France before Brexit, secured your Withdrawal Agreement residence card, renewed it, paid French tax, registered with the health system, and built a life that feels permanent. The next question many British residents now ask is whether they can become French while staying British. The answer is yes on both sides of the Channel. The British government states that dual citizenship is allowed in the United Kingdom, that you can apply for a foreign citizenship and keep your British citizenship, and that you do not need to apply for dual citizenship as a separate status. France, for its part, offers settled foreigners the route of naturalisation par décret, naturalisation by government order, which is open to British nationals on exactly the same terms as any other third-country national since Brexit. The timing is no accident. Britons who were habitually resident in France through 2020 and 2021 are now reaching the five years of residence the law normally requires, so applications from British files are rising just as prefectures are handling them entirely online. But naturalisation by decree is a favour, not a right. The minister in charge of naturalisations decides on the public interest of granting it, and can refuse or postpone an application even when every formal box looks ticked. This guide explains, for a British reader, who can apply after five years, how you prove residence, language, civic knowledge, work and good character, what a refusal, adjournment or inadmissibility decision must contain, and how you challenge it, first before the minister and then before the administrative tribunal in Nantes, which has exclusive jurisdiction. French legal terms are explained the first time they appear, every decisive rule is tied to its official source, and the court lessons come from recent judgments of the Nantes appeal court that show how judges actually reason.

I. Can a British Resident Be Naturalised French by Decree After Five Years in France?

A. Five years of habitual residence, a valid residence permit and your centre of interests in France

The starting point is that British citizens have been third-country nationals in European Union law since the end of the transition period, which means a British adult settled in France applies for citizenship under the ordinary decree procedure, not under any preserved European right. The governing principle is stated in one sentence of the Civil Code: “Hors le cas prévu à l’article 21-14-1 , l’acquisition de la nationalité française par décision de l’autorité publique résulte d’une naturalisation accordée par décret à la demande de l’étranger.” That single provision, article 21-15 of the Civil Code, carries three messages that shape everything else. Nationality by decree is acquired by a decision of the public authority, it is granted by décret, an order signed at government level, and it is granted at the request of the foreigner, which means the procedure only ever starts with your own application and never happens automatically through long residence alone. Five, ten or twenty years in the Dordogne change nothing by themselves until you file.

The residence condition most British applicants rely on is the standard five-year rule. The Code provides: “Sous réserve des exceptions prévues aux articles 21-18 , 21-19 et 21-20 , la naturalisation ne peut être accordée qu’à l’étranger justifiant d’une résidence habituelle en France pendant les cinq années qui précèdent le dépôt de la demande.” That is article 21-17 of the Civil Code, and the phrase that matters most inside it is résidence habituelle, habitual residence. The administration does not count five calendar years of occasional presence. It looks for the real seat of your life: where you sleep most nights, where your home, bills, tax household and daily routines are, and whether absences break the pattern. A British second-home owner who spends four months a year in France does not have habitual residence here, however long the pattern has lasted. A British resident who moved full-time in 2020, kept one home, filed French tax returns and can show continuous presence, normally does, and the five-year clock runs backwards from the date you file, not from the date the administration eventually decides. Gaps matter, so keep the evidence early: tax notices, health reimbursements, utility contracts and travel records that show France was continuously your home base.

Residence must also be lawful. The Code bars nationality for anyone whose stay is irregular: “Il en est de même de celui dont le séjour en France est irrégulier au regard des lois et conventions relatives au séjour des étrangers en France.” That sentence comes from article 21-27 of the Civil Code, and for a British applicant it has a concrete meaning. You must hold a valid titre de séjour, a residence permit, when you apply, and in practice that means a valid Withdrawal Agreement card, the carte de séjour d’accord de retrait, or whatever successor permit the prefecture has issued you. An expired card left unrenewed, a period of undeclared presence, or an unresolved removal order can sink the application before its merits are even examined. If your card is close to expiry, renew first and apply second, because the file must show lawful presence at the filing date. Readers who arrived after Brexit and are still on the visa-to-permit path should first secure their underlying residence position, as explained in the guide to which long-stay visa and which residence card a British newcomer needs and how to challenge a refusal, and only then think about citizenship.

A second residence trap is subtler and catches cross-Channel families. The official procedure warns that where you live in France but your husband, wife or children live abroad, French nationality can be refused. The logic is the same habitual-residence idea seen from the other side: the administration asks where the centre of your family and property interests really sits. A British applicant whose spouse and school-age children live in Kent while he keeps a flat in Paris for contract work will struggle to show that France is the genuine seat of his life, however many nights he logs. This does not mean every family must move together before you apply, but it does mean you should be ready to document why the split exists, how often the family is together in France, and where the household’s durable ties point. Investor files with the family home, the children’s schooling and the main assets all remaining in Britain are the classic profile for a refusal on this ground, and no language certificate compensates for it.

Some applicants need less than five years. The Code reduces the qualifying period to two years for three profiles: “Le stage mentionné à l’article 21-17 est réduit à deux ans : 1° Pour l’étranger qui a accompli avec succès deux années d’études supérieures en vue d’acquérir un diplôme délivré par une université ou un établissement d’enseignement supérieur français ; 2° Pour celui qui a rendu ou qui peut rendre par ses capacités et ses talents des services importants à la France ; 3° Pour l’étranger qui présente un parcours exceptionnel d’intégration, apprécié au regard des activités menées ou des actions accomplies dans les domaines civique, scientifique, économique, culturel ou sportif.” That is article 21-18 of the Civil Code. A British graduate who completed two years of higher education in France and took a French degree, a researcher or entrepreneur whose work demonstrably serves French interests, or someone with an exceptional civic, scientific, economic, cultural or sporting record in France can therefore apply after two years rather than five. These are genuinely exceptional tracks, not shortcuts for ordinary settlement, and the file must prove the achievement with diplomas, contracts, publications or official distinctions, not with assertions.

One last residence rule is easy to overlook and impossible to repair after the event. The Code states: “Nul ne peut être naturalisé s’il n’a en France sa résidence au moment de la signature du décret de naturalisation.” That is article 21-16 of the Civil Code. You must still be resident in France on the day the decree is signed, which can be a year or more after you filed. A British applicant who files, then moves back to the United Kingdom while the file is being examined, and is living in Britain when the decree comes to be signed, cannot be naturalised on that application. If a return to Britain is on the cards for work or family reasons, either defer the application or be certain the move can wait until the decree is published. The administration checks the position at signature, not only at filing, and a file that was perfect on day one fails on this single late fact.

B. Assimilation to French life: language, civic knowledge, work and a clean record

Residence gets you through the door, but the decisive test for most British files is assimilation à la communauté française, assimilation into the French community. The governing text says: “Nul ne peut être naturalisé s’il ne justifie de son assimilation à la communauté française, notamment par une connaissance suffisante, selon sa condition, de la langue, de l’histoire, de la culture et de la société françaises, dont le niveau et les modalités d’évaluation sont fixés par décret en Conseil d’Etat, et des droits et devoirs conférés par la nationalité française ainsi que par l’adhésion aux principes et aux valeurs essentiels de la République.” That is article 21-24 of the Civil Code. Note the structure. Assimilation is the headline condition, and language, history, culture, civic knowledge and republican values are listed as illustrations of it, introduced by the word notamment, which means the list is open. The administration can lawfully look beyond certificates at the whole picture of your French life, and as the court decisions examined below confirm, it does.

The language standard is functional, not academic, but it is pitched higher than many applicants expect. The same article 21-24 of the Civil Code continues: “L’intéressé justifie d’un niveau de langue lui permettant au moins de comprendre le contenu essentiel de sujets concrets ou abstraits dans un texte complexe, de communiquer avec spontanéité, de s’exprimer de façon claire et détaillée sur une grande variété de sujets.” In ordinary terms, you must follow a complex text on concrete or abstract subjects, converse spontaneously, and express yourself clearly and in detail across a wide range of topics. This is the level of someone who can handle a job interview, a parents’ evening and a disagreement with an administration in French, not someone who manages holiday transactions. Prepare with a recognised language certificate at the required level, keep the original safe, and do not assume that years of spoken kitchen French will carry you through a formal assessment. Limited exemptions exist, notably for applicants from francophone countries schooled in French, but a British applicant educated in English should assume the full requirement applies and plan the examination months before filing, because a failed or missing certificate stalls the whole file.

Alongside language sits the civic examination, the examen civique, plus a prefecture interview that many British applicants underestimate. The official procedure confirms that assimilation is checked through success in the civic examination and an interview at the prefecture, that the interview verifies your support for the essential principles and values of the Republic, that the charte des droits et devoirs du citoyen français, the charter of the French citizen’s rights and duties, sets out those principles, and that you sign the charter at the end of the interview. The Code itself closes the loop in article 21-24 of the Civil Code: “A l’issue du contrôle de son assimilation, l’intéressé signe la charte des droits et devoirs du citoyen français. Cette charte, approuvée par décret en Conseil d’Etat, rappelle les principes, valeurs et symboles essentiels de la République française.” Preparation is therefore concrete: study the official citizen’s booklet, the livret du citoyen, learn the major landmarks of French history, the meaning of the national day, the national anthem and the republican institutions, and be able to explain them in your own French words. As the second court case below shows, an applicant with twenty-two years of residence was still rejected after failing exactly these questions, so seniority in France is no substitute for revision. Missing the interview without a genuine reason can lead to the file being closed without examination, the classement sans suite, so treat the summons as the most important appointment in the procedure.

Work history is examined just as closely, because stable employment is treated as the backbone of integration. The official guidance describes professional integration as an essential condition of assimilation and defines it as having stable and sufficient income to support yourself and your tax household, the foyer fiscal. For a British applicant this raises very practical questions. Periods of unemployment are not automatically fatal, but a file showing durable inactivity, dependence on benefits, or income that cannot support the household invites an adjournment to allow integration to improve. Self-employed applicants, consultants billing British clients, and auto-entrepreneurs should present orderly books, tax returns and evidence of real, continuing activity in France rather than a bare registration. Retirees live on pensions rather than wages, and the administration looks instead at the stability and sufficiency of pension income and at genuine rootedness: property, local ties, club and community life, length of continuous presence. Whatever your situation, keep the paper trail consistent across the file, because a declared income on the application that contradicts the tax return is worse than a modest but coherent income honestly shown.

Finally, good character is a formal bar, not a background detail. The Code provides: “Nul ne peut être naturalisé s’il n’est pas de bonnes vie et moeurs ou s’il a fait l’objet de l’une des condamnations visées à l’article 21-27 du présent code. Les condamnations prononcées à l’étranger pourront toutefois ne pas être prises en considération ; en ce cas, le décret prononçant la naturalisation ne pourra être pris qu’après avis conforme du Conseil d’Etat.” That is article 21-23 of the Civil Code. The related disqualifications in article 21-27 of the Civil Code include the heaviest cases: “Nul ne peut acquérir la nationalité française ou être réintégré dans cette nationalité s’il a été l’objet soit d’une condamnation pour crimes ou délits constituant une atteinte aux intérêts fondamentaux de la Nation ou un acte de terrorisme, soit, quelle que soit l’infraction considérée, s’il a été condamné à une peine égale ou supérieure à six mois d’emprisonnement, non assortie d’une mesure de sursis.” And the same article adds expulsions, unexecuted territorial bans and irregular stay: “Il en est de même de celui qui a fait l’objet soit d’un arrêté d’expulsion non expressément rapporté ou abrogé, soit d’une interdiction du territoire français non entièrement exécutée.” and “Il en est de même de celui dont le séjour en France est irrégulier au regard des lois et conventions relatives au séjour des étrangers en France.” For most British applicants the real question is not a prison sentence but the middle ground: motoring convictions, fines, tax penalties, undeclared work, or a driving offence after losing all licence points. As the first court case below demonstrates, even a single recent fine for driving without a licence after a total points loss supported a two-year postponement. Before filing, order your French criminal record extract, check what appears on bulletin no. 2, regularise anything pending, and if in doubt let time pass so the incident is genuinely old on the day the minister decides, not merely old on the day you file.

II. What Happens If the Minister Refuses or Adjourns Your Naturalisation Application?

A. Rejection, adjournment or inadmissibility: how the decision is made and what it must contain

British applications are now filed online through the official teleservice, with originals kept ready for the interview, and the procedure that follows is strictly timetabled. Once the file is registered you receive a receipt, the récépissé, and the administration then has eighteen months from that receipt to answer. The period falls to twelve months if you already show ten years of habitual residence in France on the receipt date, and it can be extended once by three months. These are outer limits, not promises of speed, and the prefecture will use the time to verify civil status documents, request additions, run background checks and summon you to the assimilation interview. If the examining service asks for extra documents or steps, it sets a deadline, and missing that deadline without good reason means the file can be closed without examination. From the first receipt, therefore, watch your online personal space, answer every request inside the stated time, and report changes in family, work or address through the same channel, because a file that goes silent looks like a file whose holder has lost interest or left France.

When the instruction ends, the minister’s decision takes one of three unfavourable forms, and the vocabulary matters because each carries different consequences. A declaration of inadmissibility, the irrecevabilité, means a legal condition was not met: too short a residence, no valid permit, a disqualifying conviction. If the missing condition later appears, you may file a fresh application. A rejection, the rejet, and a postponement, the ajournement, both mean the project was judged inopportune, not yet conceivable or not conceivable at all. The postponement imposes a waiting period or conditions, for example two years to demonstrate better professional integration, after which you may apply again. The legal basis for both sits in the 1993 procedure decree: “Si le ministre chargé des naturalisations estime qu’il n’y a pas lieu d’accorder la naturalisation ou la réintégration sollicitée, il prononce le rejet de la demande. Il peut également en prononcer l’ajournement en imposant un délai ou des conditions (…)” That is article 48 of the decree of 30 December 1993 on nationality declarations and naturalisation decisions, cited verbatim by the Nantes appeal court in CAA Nantes, 12 September 2025, no. 24NT02593. The full decree text is decree no. 93-1362 of 30 December 1993 on nationality declarations and naturalisation decisions, whose articles 48 and 49 are quoted above through the judgments that apply them. Two practical traps surround refiling. A new application lodged less than five years after notification of a rejection can be closed without examination unless you show genuinely new circumstances, and a new application lodged before an adjournment period has expired can be closed the same way. An adjournment is therefore not an invitation to reapply immediately with a slightly thicker file. It is an instruction to wait out the period and return with a transformed situation.

Every unfavourable decision must be reasoned in law and fact. The same decree provides: ” Toute décision déclarant irrecevable, ajournant ou rejetant une demande de naturalisation ou de réintégration dans la nationalité française prise en application du présent décret est motivée conformément à l’article 27 de la loi n° 98-170 du 16 mars 1998 relative à la nationalité. ” That is article 49 of the 1993 decree, as set out in CAA Nantes, 12 September 2025, no. 24NT02593. In practice the decision must cite the legal provisions applied and state the facts held against you: which condition failed, which offence, which interview findings, which missing income. The 2025 Nantes case shows the standard applied. The minister’s postponement decision referred to articles 45 and 48 of the decree and set out that the applicant had driven a motor vehicle despite being ordered to surrender his licence after losing all his points, and had been fined 350 euros for it by the Pontoise court on 19 October 2018. The appeal court held that the decision therefore contained the legal and factual considerations forming its basis, and rejected the plea of insufficient reasoning. The lesson for British readers is that a decision which names the rule and the fact survives this challenge, so do not spend your appeal arguing the letter is too short when it plainly states both. Attack the assessment itself, or show the fact is wrong, old, or already wiped by rehabilitation or removal from the second bulletin of the criminal record.

A final formal check concerns who signed. Naturalisation refusals and postponements are signed under delegated authority, and the delegation must exist and be published. In the 2025 case the signatory held a delegation granted by a published decision of 30 August 2018 from the director of reception, accompaniment of foreigners and nationality, herself appointed by a published decree, and the incompetence plea failed. Delegations are therefore routinely in order, but the point is worth one look in every file, because a missing or unpublished delegation is one of the rare defects that annuls without any debate on the merits. Ask for the full decision with its signature block, check the official journal references it cites, and only then move to the substance of the challenge.

B. How to challenge: the ministerial appeal, the Nantes tribunal, and what judges actually accept

The challenge runs in two stages, and the order and deadlines are strict. Within two months of notification of the unfavourable decision, you lodge an administrative appeal, the recours administratif or hierarchical appeal, to the minister in charge of naturalisations. For online applications this appeal must go through the form in your personal space under notifications, and any other channel risks inadmissibility unless a proven technical impossibility prevented online filing. If the minister answers negatively, or says nothing for four months from receipt of your appeal, you then have two months to bring court proceedings, the recours contentieux, before the administrative tribunal of Nantes, the tribunal administratif de Nantes, which hears these cases for the whole country. The two-month court deadline runs from notification of the express negative reply, or, where there was silence, from the documents showing receipt of your appeal, so keep the acknowledgement of receipt and diarise both dates on the day you appeal. Missing either deadline ends the challenge, whatever its merits, and leaves only a future fresh application after the waiting rules described above.

Before drafting, understand what the judge can and cannot do, because naturalisation litigation turns on one idea: the minister’s broad discretionary power, the large pouvoir d’appréciation. The Nantes appeal court restates it in almost every judgment: “Il appartient au ministre en charge des naturalisations, eu égard aux dispositions précitées des articles 21-15 du code civil et 48 du décret du 30 décembre 1993, de porter une appréciation sur l’intérêt d’accorder la naturalisation à l’étranger qui la demande. Dans le cadre de cet examen d’opportunité, il peut légalement prendre en compte les éléments défavorables le concernant.” That passage comes from CAA Nantes, 12 September 2025, no. 24NT02593, and the companion formulation in the assimilation context reads: “En vertu de ces dispositions, il appartient au ministre chargé des naturalisations de porter une appréciation sur l’intérêt d’accorder la nationalité française à l’étranger qui la sollicite. Dans le cadre de cet examen d’opportunité, il peut légalement prendre en compte le degré d’assimilation à la société française du postulant.” That second passage comes from CAA Nantes, 13 January 2026, no. 25NT00015. In plain terms, the minister judges the public interest of making you French, may lawfully weigh anything unfavourable, and the court does not substitute its own view. It annuls only for unlawfulness, flawed procedure, wrong facts, or manifest error of assessment, the erreur manifeste d’appréciation, meaning a conclusion no reasonable authority could have drawn from the file. A decision the judge would not have taken himself still stands if it was open to the minister to take it.

The 2025 adjournment case shows how high that bar sits. The applicant, an Algerian national born in 1955 with certain long-standing professional, social and family integration in France, had driven without a licence after being ordered to surrender it following the loss of all his points, and had been fined for it less than three years before the minister’s decision of 15 April 2021, which postponed his application by two years. The appeal court first annulled the Nantes tribunal’s judgment of 21 June 2024, because the tribunal had failed to answer the plea alleging insufficient reasoning, which was not inoperative, and then, deciding the case itself, upheld the minister. Its words, in CAA Nantes, 12 September 2025, no. 24NT02593, deserve full quotation: “Eu égard, d’une part, à la gravité de ce comportement récent à la date de la décision contestée et, de l’autre, au large pouvoir d’appréciation dont le ministre de l’intérieur dispose quant à l’opportunité d’accorder ou non la nationalité française à la personne qui la sollicite, malgré l’insertion professionnelle, sociale et familiale certaine et ancienne en France de M. B…, celui-ci n’est pas fondé à soutenir que la décision contestée d’ajournement à deux ans est entachée d’une erreur manifeste d’appréciation.” One recent driving offence therefore outweighed decades of integration, because it was recent on the decision date and the minister’s discretion is wide. For British applicants the operational lesson is blunt: clear the record and let time do its work before filing, because the minister judges recency at the decision date, and a fine you consider minor can cost two years.

The 2026 assimilation case is even more instructive for British files, because it turns on the interview so many confident English speakers assume they will sail through. The applicant, a Turkish national, had lived in France for twenty-two years, yet the prefecture interview of 16 July 2020 found weak French and very poor knowledge of France: she could not explain the French Revolution, the meaning of the national day, or the name of the national anthem, and the report concluded integration was not achieved. She argued that cancer treated by chemotherapy caused memory trouble and that stress had affected her performance. The court answered each point. Her state of health had not been raised during the examination of her application, the questions were not shown to be pitched above her educational level, the interviewing officer was not shown to have been intimidating, and the medical evidence, even assumed genuine, could not alone explain the gaps found. The court therefore held, in CAA Nantes, 13 January 2026, no. 25NT00015: “Dans ces conditions, le ministre a pu, eu égard au large pouvoir d’appréciation dont il dispose pour apprécier l’opportunité d’accorder la nationalité française au ressortissant étranger qui la sollicite, rejeter la demande de naturalisation de Mme C… pour les motifs mentionnés ci-dessus sans commettre d’erreur manifeste d’appréciation.” The appeal was rejected in full, including the injunction and costs claims. Three rules for British applicants follow. First, twenty-two years of residence did not compensate for a failed interview, so length of stay never excuses poor preparation. Second, difficulties such as illness, stress or a hostile atmosphere must be raised with evidence during the procedure, not revealed for the first time before the judge. Third, the interview report is the centre of the case, so request access to the file, read the report, and build the ministerial appeal around precise answers to each recorded finding rather than general statements about loving France.

A well-built challenge therefore works in layers. At the ministerial stage, correct every factual error with documents, show what has changed since the decision (stable job, completed training, clean record extract, new language certificate), and explain unfavourable facts rather than ignoring them, because silence reads as indifference. At the tribunal stage, plead in the order judges examine: competence and signature, reasoning, material accuracy of the facts, then manifest error, supporting each with exhibits the minister did not have or misread. Ask the court, if it annuls, to order reconsideration within a stated time rather than to grant nationality directly, since judges remit discretionary grants to the minister except in the clearest cases. And throughout, respect the parallel waiting rules: if the adjournment period is still running, energy spent on a premature fresh application is wasted, because it can be closed without examination. The same discipline applies to the five-year shadow after a rejection. Sometimes the strongest move after a refusal is not an immediate new file but a patient, documented year of irreproachable integration followed by a file the minister cannot describe as inopportune.

Conclusion

French citizenship by decree is firmly within reach of a British resident who treats it as a legal procedure rather than a reward for long stay. Five years of genuine habitual residence with a valid permit, the centre of your interests in France, working French pitched at understanding complex subjects and speaking clearly across many of them, real civic knowledge that survives a prefecture interview, stable and sufficient means, and a clean recent record together make a file the minister can grant. The same file, filed a year too early, weakened by an unrevised interview, stained by a recent driving conviction, or undermined by a family life visibly centred across the Channel, makes a refusal or a two-year adjournment that the Nantes courts will uphold under the minister’s wide discretion. The two 2025 and 2026 judgments say it plainly: even long integration does not neutralise a recent offence, and even twenty-two years of residence do not neutralise a failed assimilation interview. Prepare the language and the civic examination before filing, clear the record and let it age, keep every deadline from receipt to ministerial appeal to the Nantes tribunal, and challenge an adverse decision on its facts and its reasoning with documents rather than adjectives. British nationality is safe throughout, since the United Kingdom lets you keep it, and the French decree, once signed while you are still resident here, closes the post-Brexit circle: the settled resident becomes a citizen. The full official procedure, forms and time limits are kept up to date on the service-public guide to naturalisation by decree and the British position on dual status on the gov.uk guide to dual citizenship.