You live in Lyon, Bordeaux or a village in the Dordogne. Your contract says London, your line manager sits in Manchester, and your salary lands in pounds in a British bank account. Since Brexit, that everyday arrangement has become a cross-border legal file: France sees a worker on its soil, and French law attaches consequences to that fact alone — social security contributions, a right-to-work check, income tax, and, for your employer, the risk of being treated as operating in France without being registered there. The good news is that the system has a dedicated track for exactly this situation, run by the URSSAF office for foreign firms, and the boundary with neighbouring regimes — the short posting of staff to France, and the self-employed freelancer — is drawn in published statutes and recent court decisions. This article explains, for a British reader, where you and your United Kingdom employer stand after Brexit: which country’s social security takes your contributions, which residence and work papers you need, where your salary is taxed and how the double-tax treaty prevents both countries taxing the same pay, and which challenge routes exist when the URSSAF or the tax office sends a bill you dispute. Every French term is translated when it first appears.
I. Working From France for a British Employer: French Social Security and the Right to Work
A. Your Contributions Belong to France, and Your Employer Registers With the Foreign-Firms Service
French social security starts from a territorial principle: work performed in France is insured in France. The statute states it in the broadest terms: “Sont affiliées obligatoirement aux assurances sociales du régime général, quel que soit leur âge et même si elles sont titulaires d’une pension, toutes les personnes quelle que soit leur nationalité, de l’un ou de l’autre sexe, salariées ou travaillant à quelque titre ou en quelque lieu que ce soit, pour un ou plusieurs employeurs et quels que soient le montant et la nature de leur rémunération, la forme, la nature ou la validité de leur contrat ou la nature de leur statut.” (Article L311-2 of the Social Security Code). Nationality, currency of pay and the employer’s address change nothing: if you habitually work from your home in France, you fall under the French scheme, and your British employer owes French employer and employee contributions on your salary. Before Brexit, European coordination rules moved many cross-border workers between schemes with a portable document; since the end of the transition period, a British remote worker who lives and works in France is, in the standard case, simply insured in France from the first day of that stable arrangement.
That outcome surprises employers who assume that keeping a worker on British payroll keeps them in the British system. It does not. The French position is that contributions follow the place of work, and only a formal secondment procedure — with a certificate proving the worker remains attached to the home scheme — displaces it. The Cour de cassation, the supreme court for civil and criminal matters, restated the logic in a decision of 16 October 2025 concerning employees of a foreign company working on French soil: “les agents de contrôle des organismes de sécurité sociale et des caisses de mutualité sociale agricole, agréés à cet effet et assermentés, vérifient les déclarations qui doivent être faites par l’employeur aux organismes de protection sociale et de recouvrement des contributions et cotisations sociales en vertu des dispositions légales en vigueur en recueillant auprès de l’employeur les documents, quels que soient leur forme et leur support, qui permettent d’établir si l’employeur dispose d’une affiliation à la sécurité sociale française.” (Cass. 2nd civil chamber, 16 October 2025, appeal no. K 23-14.039, quashing the Colmar appeal judgment of 9 February 2023). The operative part is blunt: “CASSE ET ANNULE, en toutes ses dispositions, l’arrêt rendu le 9 février 2023, entre les parties, par la cour d’appel de Colmar”. Where no secondment certificate is produced, the adjustment stands. For a British remote worker, the certificate route is in practice closed: secondment (détachement) in French law means a temporary posting by an employer established abroad, defined as follows: “Un employeur établi hors de France peut détacher temporairement des salariés sur le territoire national, à condition qu’il existe un contrat de travail entre cet employeur et le salarié et que leur relation de travail subsiste pendant la période de détachement.” (Article L1262-1 of the Labour Code). A permanent work-from-home arrangement in France is the opposite of a temporary posting, so the French scheme applies without an expiry date.
The administration has built a one-stop track for this exact fact pattern. The URSSAF — the network of bodies that collects social contributions — states on its Foreign Firms service page that an employer with no premises in France that hires an employee falling under the French social security scheme must declare and pay the French social contributions in France. The page expressly lists permanent work on French territory under the French scheme among the covered cases. Registration runs through the Foreign Firms service (service des firmes étrangères), which then notifies the other bodies involved — the statistics institute, the pension fund and the tax office for non-residents — so the employer does not have to open a French subsidiary or branch. The practical sequence is therefore short: the employer registers, files the pre-hiring declaration (déclaration préalable à l’embauche) for the worker, issues French-compliant payslips and pays contributions at French rates. Skipping that sequence is treated as concealed work (travail dissimulé): “Est réputé travail dissimulé par dissimulation d’emploi salarié le fait pour tout employeur : 1° Soit de se soustraire intentionnellement à l’accomplissement de la formalité prévue à l’article L. 1221-10 , relatif à la déclaration préalable à l’embauche ; 2° Soit de se soustraire intentionnellement à la délivrance d’un bulletin de paie ou d’un document équivalent défini par voie réglementaire, ou de mentionner sur le bulletin de paie ou le document équivalent un nombre d’heures de travail inférieur à celui réellement accompli, si cette mention ne résulte pas d’une convention ou d’un accord collectif d’aménagement du temps de travail conclu en application du titre II du livre Ier de la troisième partie ; 3° Soit de se soustraire intentionnellement aux déclarations relatives aux salaires ou aux cotisations sociales assises sur ceux-ci auprès des organismes de recouvrement des contributions et cotisations sociales ou de l’administration fiscale en vertu des dispositions légales.” (Article L8221-5 of the Labour Code). The criminal courts apply that text to foreign employment setups too: in a case involving foreign workers on a French construction site, the criminal chamber noted that “La société Elco a été notamment déclarée coupable du chef de travail dissimulé par dissimulation de salariés, faute d’avoir procédé aux déclarations préalables à l’embauche et aux déclarations aux organismes de protection sociale appropriées.” (Cass. criminal chamber, 12 January 2021, appeal no. G 17-82.553). Intent to evade must still be proved, but a British employer that knowingly keeps a France-based worker entirely off French filings is exposed to reassessment for the whole period plus surcharges, and in serious cases to prosecution.
Two neighbouring situations must not be confused with yours. The first is the posted worker (salarié détaché): an employee sent temporarily from Britain to France for a mission, who may remain under British social security with the proper certificate. That regime, with its prior declaration on the SIPSI portal and its short time windows, is described in our companion article on British posted workers. If your presence in France is stable and open-ended, you are not posted — you are locally insured. The second is the freelancer (auto-entrepreneur): a Briton who invoices clients from France needs a different visa and pays into the self-employed scheme, covered in our guide for British freelancers. If you have one employment contract with one British employer and take orders from that employer, you are an employee, and the Foreign Firms track is yours. Two companion pieces cover the neighbouring questions in depth: which employment law governs your contract and how to challenge a sacking, and the payroll mechanics of DPAE registration and payslips. This article takes the fiscal and contentious angle: where your salary is taxed, how the treaty removes double tax, when your employer risks a taxable presence, and how each bill is challenged.
B. Your Right to Work: Visa, Residence Permit and the Employer’s Prior Authorisation
Social security is only half of the file. Since Brexit, a British citizen is a third-country national for immigration purposes, and working in France requires both a right to stay and a right to work. The entry rule is general: “tout étranger âgé de plus de dix-huit ans qui souhaite séjourner en France pour une durée supérieure à trois mois doit être titulaire de l’un des documents de séjour suivants : 1° Un visa de long séjour ;” (Article L411-1 of the Code on the Entry and Residence of Foreigners and Asylum). In practice the British remote worker applies from the United Kingdom for a long-stay visa that allows salaried work, then converts it after arrival into a temporary residence card (carte de séjour temporaire) and later a multi-year card (carte de séjour pluriannuelle), as explained in our hub guide for British newcomers. Nationals covered by the Withdrawal Agreement follow their own card track instead. One warning from daily practice: entering on a 90-day visa waiver and starting salaried remote work from France does not regularise anything — the short stay authorises presence, not employment.
Alongside your papers, your employer needs its own prior permission. The Labour Code provides: “Un étranger autorisé à séjourner en France ne peut exercer une activité professionnelle salariée en France sans avoir obtenu au préalable l’autorisation de travail mentionnée au 2° de l’ article L. 5221-2 .” (Article L5221-5 of the Labour Code). For many British hires this authorisation travels with the visa or residence card procedure, and some cards — such as the multi-year talent or intra-group cards — carry the right to work by themselves. But where the card applied for does not include it, the employer must request the work authorisation before you start, and employing you without it exposes the company to a special contribution payable to the immigration office in addition to any criminal liability for employing a foreign worker without permission. Check the exact wording of the visa and card before the first payslip, not after.
II. Paying Tax on a British Salary From France: Residence, the Treaty and How to Dispute the Bill
A. France Will Usually Treat You as Tax-Resident From the Day You Settle
French income tax starts from the domicile for tax purposes (domicile fiscal). The baseline rule is short: “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. Celles dont le domicile fiscal est situé hors de France sont passibles de cet impôt en raison de leurs seuls revenus de source française.” (Article 4 A of the General Tax Code). The tests that follow are alternative — meeting any one of them is enough: “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 ; b. Celles qui exercent en France une activité professionnelle, salariée ou non, à moins qu’elles ne justifient que cette activité y est exercée à titre accessoire ;” (Article 4 B of the General Tax Code), while a third test catches “c. Celles qui ont en France le centre de leurs intérêts économiques.” (Article 4 B of the General Tax Code, third test). A British remote worker whose home, family life and daily work are all in France normally meets the first test, and often the second and third as well. The consequence is worldwide taxation in France: the British salary is declared on the French return — the main form 2042 plus the foreign-income schedule 2047 — as explained in our walk-through of the first French tax return. Because the employer withholds British payroll tax at source, the treaty mechanism then steps in to cancel the overlap: France taxes, and grants a credit for the British tax attributable to the same income, so the same pound of salary is not taxed twice in full. Keep every British payslip and P60, because the French tax office asks for them when it checks the credit.
The bilateral double-tax convention between France and the United Kingdom organises that sharing. Its standard architecture for employees is familiar to advisers on both sides of the Channel: the state of residence taxes the salary, the state where the work is physically done may also tax it, and short assignments abroad stay taxable only at home when three conditions coincide — a limited number of days of presence, payment by a non-resident employer, and no local cost-bearing. A remote worker who lives and works year-round in France fails those conditions by definition: more than half the year in France, daily work in France, home in France. Treaty residence then follows France under the tie-breaker order — permanent home, then centre of vital interests, then habitual presence — and the salary falls primarily to France, with Britain giving relief on its side. The precise treaty wording matters at the margins, for example for split years, for directors’ fees, or for government-service pensions that follow their own articles, so read the convention text for your exact category rather than assuming the employee rule covers everything. A useful cross-check on the British side is the official guidance on social security and tax when working abroad (GOV.UK, Social Security Abroad NI38), which reminds workers that leaving Britain does not by itself end British obligations. Declare in both countries where a filing duty exists, claim the treaty credit where the treaty gives it, and never assume that paying in one country exempts you from filing in the other.
Choice of law in the contract deserves a paragraph of its own, because British employers often insert a clause saying the contract is governed by English law and assume the matter is closed. Party choice is real but bounded. In a cross-border employment dispute the social chamber recalled the European rule verbatim: “Aux termes de l’article 3, § 1, du Règlement (CE) n° 593/2008 du Parlement européen et du Conseil du 17 juin 2008 sur la loi applicable aux obligations contractuelles (Rome I), le contrat est régi par la loi choisie par les parties.” (Cass. social chamber, 8 January 2025, appeal no. N 23-10.637). The same judgment adds the companion rule on validity: “Aux termes de l’article 10, § 1, du même règlement, l’existence et la validité du contrat ou d’une disposition de celui-ci sont soumises à la loi qui serait applicable en vertu du présent règlement si le contrat ou la disposition étaient valables.” But in employment matters the Rome I regulation preserves the employee’s mandatory protections of the law that would apply without choice — typically the law of the habitual place of work, which for you is France. An English-law clause therefore cannot strip away French minimum wage, working-time limits, dismissal protection or the jurisdiction of the French employment tribunal (conseil de prud’hommes) where the tests point to France. Draft the clause, by all means, and choose English for interpretation comfort — then comply with the French floor beneath it.
B. The Employer’s Two Extra Risks: a Taxable Presence and the URSSAF Reassessment
Beyond payroll compliance, the British employer faces a corporate question: does a worker based permanently in France create a taxable presence there? French domestic law taxes profits by taking into account “uniquement des bénéfices réalisés dans les entreprises exploitées en France”, alongside “ceux dont l’imposition est attribuée à la France par une convention internationale relative aux doubles impositions.” (Article 209, I of the General Tax Code). A single home-based employee who merely performs their own duties — writing code, designing, marketing — does not by itself amount to operating a business in France in most readings. The risk rises steeply when that employee habitually concludes contracts in the company’s name, holds stock, or acts as the company’s local decision-maker: the treaty concept of a permanent establishment can then attach, and with it French registration, accounting and corporation-tax duties. Keep the authority matrix in writing, limit signature powers, and route contract conclusions through the United Kingdom while the worker executes from France. Where the role genuinely requires deal-closing power in France, take advice before the pattern settles — restructuring after a tax audit is far costlier than a mandate drafted on day one.
When a bill does arrive, each administration has its own challenge ladder, and the ladders run in parallel. Against a URSSAF reassessment (redressement), the first step is the employer’s adversarial reply to the observation letter (lettre d’observations), within the stated deadline, attaching the registration proof, the pre-hiring declarations, the payslips and any secondment certificates for genuinely posted colleagues. If the formal demand (mise en demeure) follows, the employer files a complaint with the collection body’s appeals commission (commission de recours amiable), then brings the dispute before the judicial court (tribunal judiciaire) specialised in social protection litigation, and onward to the court of appeal. The October 2025 quashing decision shows why the paper trail matters: controllers verify affiliation by collecting the employer’s documents, and a company that cannot produce them loses the argument before it starts. Against an income-tax assessment, the worker files an online or paper claim (réclamation) to the tax office, then appeals to the administrative court (tribunal administratif) within two months of the rejection, with the treaty credit computation and the British tax proofs as exhibits. Against a residence-permit or work-authorisation refusal, the route runs from an informal appeal (recours gracieux) to the administrative court, where the judge checks the legal basis, the file as a whole and proportionality. In all three lanes, time limits are short and some run from notification, so diary every deadline on receipt and keep proof of sending.
Remote work from France also sits inside ordinary French employment law. The Labour Code defines the setup plainly: “le télétravail désigne toute forme d’organisation du travail dans laquelle un travail qui aurait également pu être exécuté dans les locaux de l’employeur est effectué par un salarié hors de ces locaux de façon volontaire en utilisant les technologies de l’information et de la communication.” (Article L1222-9 of the Labour Code). The framework — collective agreement or employer charter after consulting the staff committee, or individual agreement recorded by any means — fixes passage in and out of remote work, working-time control, contact hours and equipment. Apply it across the Channel: a written remote-work addendum stating the French work address, the applicable hours, the employer’s right to verify activity, accident-at-work reporting from home, and cost reimbursement avoids the most common disputes. If the relationship ends, French dismissal law and notice rules apply to a France-based worker under French law regardless of what the English-language contract says about at-will flexibility — a point developed in our guide on dismissals of British employees in France.
Conclusion
A British citizen who works permanently from France for a British employer lives under French social security, needs French permission to stay and to work, and normally pays French tax on the worldwide salary with treaty relief for British deductions. The employer registers with the Foreign Firms service rather than opening a French company, files French payroll, limits signature authority to contain the taxable-presence risk, and keeps the documents that defeat a reassessment. None of this requires leaving the British payroll system emotionally — it requires mirroring it in France administratively. Set the three files straight at the start — residence and work papers, URSSAF registration with payslips, tax residence with treaty credit — and the arrangement is stable for years; neglect them, and the first control rebuilds the whole history at penalty rates. The order of operations is therefore simple: secure the visa and work authorisation before day one, register the employment in France before the first payslip, declare the salary in France with the treaty credit, and challenge any assessment through its proper lane before its deadline expires.