You live in London, New York, Dubai or Singapore. You have just created a French subsidiary, a SAS (société par actions simplifiée, the flexible French joint-stock company) or a SARL (société à responsabilité limitée, the French limited-liability company), and the Kbis (the official company identity certificate issued by the commercial court registry, the greffe) is on its way. To get things moving, you send one of your trusted employees to Paris for a few months: find an office, meet clients, hire a local assistant, open the bank account in person. The employee keeps their foreign employment contract, you keep paying social contributions at home, and you add an A1 certificate (the European form proving the employee stays covered by their home social security during a posting) to the file. Everything looks covered.

It is not. France treats this situation as a posting of workers, known in French as détachement, and it applies a complete set of prior formalities from the very first day of work on French soil. Before the employee starts, you must file an electronic prior declaration on SIPSI (the online posting-declaration system run by the Ministry of Labour), appoint a representative established in France, keep a file of documents translated into French available at the place of work, and guarantee the employee the same core working conditions as employees of French companies in the same sector, starting with pay, working time and overtime rates. Each missing obligation can cost up to 4,000 euros per posted worker, doubled on a repeat offence, with a ceiling of 500,000 euros, and a posting built on sham arrangements can be reclassified as concealed work, travail dissimulé, which is a criminal offence. The good news is that most of these risks can be neutralised in a few days if you act in the right order, and an unjustified fine can be challenged before the administrative court.

This guide explains, in English and for a business reader, how to post your employee to France lawfully, what the inspection du travail (the French labour inspectorate) checks first, what a defective A1 certificate really changes since a June 2026 criminal decision, and the exact steps to regularise and contest a fine from abroad.

I. Posting Your Employee to France Is Lawful Only If You Declare It Before Day One

A. Who Counts as a Posted Worker and Which French Rules Apply From the First Day

French law starts from a simple principle. The statute provides: « 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. » This is article L1262-1 of the Labour Code. Two conditions therefore define a lawful posting: a genuine employment contract with the sending company, and a working relationship that continues during the stay. An employee hired locally in Paris on a French contract is not posted; a consultant with no employment contract is not posted either, but sending them under a service contract while they work like an employee creates a far worse risk, discussed below.

The same article lists three posting patterns, and foreign founders use the second one most: « 1° Soit pour le compte de l’employeur et sous sa direction, dans le cadre d’un contrat conclu entre celui-ci et le destinataire de la prestation établi ou exerçant en France ; 2° Soit entre établissements d’une même entreprise ou entre entreprises d’un même groupe ; 3° Soit pour le compte de l’employeur sans qu’il existe un contrat entre celui-ci et un destinataire. » (article L1262-1 of the Labour Code) Sending your London employee to set up your French subsidiary is the intra-group case of paragraph 2, even if the subsidiary has just been created and has no staff yet. Sending the same employee to perform a contract for a French client is paragraph 1. Both require the same declarations.

From the first day, the posted employee must receive equal treatment with employees of French companies in the same sector. Article L1262-4 of the Labour Code states: « L’employeur détachant temporairement un salarié sur le territoire national lui garantit l’égalité de traitement avec les salariés employés par les entreprises de la même branche d’activité établies sur le territoire national, en assurant le respect des dispositions légales et des stipulations conventionnelles applicables aux salariés employés par les entreprises de la même branche d’activité établies sur le territoire national, en matière de législation du travail, pour ce qui concerne les matières suivantes : » The list that follows is long and practical: individual and collective freedoms, non-discrimination, maternity and paternity leave, the right to strike, working time, compensatory rest, public holidays, paid leave, remuneration within the meaning of the equal-pay rules including overtime uplifts, health and safety, illegal-work rules, and reimbursement of travel, meal and accommodation expenses linked to the assignment. In plain terms, your posted developer, sales manager or technician is owed the French 35-hour week framework, French overtime rates, the applicable collective agreement minimum (convention collective), and French health and safety standards from day one, whatever their home contract says. If the posting on the same job exceeds twelve months, the rule hardens: from the thirteenth month, almost the entire Labour Code applies as if the company were established in France, and replacing one posted worker with another on the same post does not reset the clock, since cumulative time counts.

Two traps deserve emphasis because they surprise foreign employers every week. First, fulfilling the declaration duties does not make the posting lawful by itself: the statute expressly provides that completing the declaration and appointing a representative does not presume the posting is genuine, so a sham posting remains punishable even with a perfect SIPSI receipt. Second, social security and labour law are two separate tracks. The A1 certificate settles which country’s social contributions apply, under European coordination rules, but it exempts you from nothing in labour law: no declaration, no representative, no pay top-up. Founders who chose their French vehicle with the guide to choosing between a SAS, a SARL, a branch and a subsidiary from abroad sometimes assume the subsidiary structure absorbs the employee automatically; it does not, until the employee is hired on a French contract or a compliant posting file exists.

B. The Prior SIPSI Declaration, the Representative in France and the Translated File

The central duty is a prior declaration to the labour inspectorate of the place where the work starts, filed electronically on SIPSI before the posting begins. Article L1262-2-1 of the Labour Code provides: « L’employeur qui détache un ou plusieurs salariés, dans les conditions prévues aux 1° et 2° de l’article L. 1262-1 et à l’article L. 1262-2 , adresse une déclaration, préalablement au détachement, à l’inspection du travail du lieu où débute la prestation. » The DREETS (direction régionale de l’économie, de l’emploi, du travail et des solidarités, the regional authority supervising the labour inspectorate) confirms on its official pages that every employer established outside France that posts workers for a service must send this declaration before the posting starts, through the electronic channel. A declaration filed after the inspector knocks on the door is a late declaration: it helps for the future but it does not erase the offence for the days already worked.

The same article requires a local contact person: « L’employeur mentionné au I du présent article désigne un représentant de l’entreprise sur le territoire national, chargé d’assurer la liaison avec les agents mentionnés à l’article L. 8271-1-2 pendant la durée de la prestation. » (article L1262-2-1 of the Labour Code) This representative (représentant en France) can be the subsidiary itself once registered, a lawyer, or any reachable person established in France; what matters is that the inspector can contact someone who produces the file within hours. Foreign founders often designate the future office manager or the domiciliation company, but a domiciliation address alone, without a reachable human being holding the documents, fails the test.

Third, the file must be physically or digitally available at the place of work, in French. Article L1263-7 of the Labour Code states: « L’employeur détachant temporairement des salariés sur le territoire national, ou son représentant mentionné au II de l’article L. 1262-2-1 , présente sur le lieu de réalisation de la prestation à l’inspection du travail des documents traduits en langue française permettant de vérifier le respect des dispositions du présent titre. » In practice the inspector asks for the SIPSI receipt, the employment contract, recent payslips, proof of actual payment at the French minimum level, working-time records, and the A1 certificate. Payslips in English with no translation, a home-country pay level below the French sector minimum, or no time records for a 45-hour week are the three findings that most often turn a routine visit into a fine. Prepare the file before the flight, not after the visit: translation takes a day, and the inspector rarely grants one.

A final practical point for founders: if your French client or your subsidiary receives the posted worker, it carries its own verification duties, and a missing SIPSI declaration on your side can trigger a separate fine against the French host. Check the contract chain before anyone boards the plane, and keep written proof that each party filed what it owed.

II. What a Missing Paper Really Costs and How to Fight Back From Abroad

A. Administrative Fines per Worker, Criminal Concealed-Work Exposure and the A1 Certificate Trap

Missing the declaration, the representative or the translated documents is punished by an administrative fine, pronounced without going through a criminal court. Article L1264-1 of the Labour Code provides: « La méconnaissance par l’employeur qui détache un ou plusieurs salariés d’une des obligations mentionnées à l’article L. 1262-2-1 , au troisième alinéa du II de l’article L. 1262-4, à l’article L. 1262-4-4 ou à l’article L. 1263-7 est passible d’une amende administrative, dans les conditions prévues à l’article L. 1264-3 . »

The French host is not spared: article L1264-2 of the Labour Code exposes the client, the main contractor or the user company to the same administrative fine when its contractor failed its own posting duties. If you post your employee to your own subsidiary, the subsidiary as host and your foreign company as sender can therefore be fined on the same facts, which doubles the financial exposure of the group.

The amounts are set by article L1264-3 of the Labour Code: « L’amende administrative mentionnée aux articles L. 1264-1 et L. 1264-2 est prononcée par l’autorité administrative compétente, après constatation par un des agents de contrôle de l’inspection du travail mentionnés aux articles L. 8112-1 et L. 8112-5. Le montant de l’amende est d’au plus 4 000 € par salarié détaché et d’au plus 8 000 € en cas de réitération dans un délai de deux ans à compter du jour de la notification de la première amende. Le montant total de l’amende ne peut être supérieur à 500 000 €. » Three figures matter for your budget: 4,000 euros per worker per breach, 8,000 on a repeat within two years of the first notification, and an absolute ceiling of 500,000 euros. The same article adds the points that decide real cases: the authority must weigh the circumstances, the seriousness, your behaviour including good faith, and your resources; the administration has two full years from the breach to act; and recovery is enforced like State debts, with no suspensive effect from a challenge to enforcement. A fine notified to your foreign head office is therefore immediately enforceable in principle, even while you contest it, which is why the contestation strategy must be built from day one rather than after the deadline.

Beyond the fine, two criminal shadows hang over sloppy postings. The first is concealed work, which covers both hiding a business activity that should be registered and hiding employment that should be declared. The criminal chamber of the Court of Cassation confirmed that a company registered in another European Union Member State which opens a genuine establishment in France must register it: Cass. crim., 2 March 2021, No. 19-80.991, ECLI:FR:CCASS:2021:CR00158, available at Court of Cassation decision 19-80.991. The Court reasoned from European freedom-of-establishment case law that incorporating abroad to operate mainly in France is not in itself unlawful, outside fraud, but that the resulting establishment must still be registered. A posted employee who in reality runs a permanent French office, signs contracts daily and never rotates home looks less like a posting and more like an unregistered establishment, and that is where labour fines turn into criminal files, bans on managing companies, and confiscations.

The second shadow is the A1 certificate trap, clarified by a very recent decision every foreign employer should know. On 9 June 2026 the criminal chamber upheld judges who had set aside A1 certificates obtained fraudulently: Cass. crim., 9 June 2026, No. 24-85.090, ECLI:FR:CCASS:2026:CR00501, available at Court of Cassation decision 24-85.090. The Court deduced from the European Altun and Vueling case law that the dialogue and conciliation procedure under Regulation 883/2004 on social security coordination is a mandatory prerequisite before a final finding of fraud, but that a perfunctory confirmation by the issuing State, which does not answer the concrete evidence submitted by the French institutions, is not a genuine re-examination. In that situation the French criminal court may set the certificates aside once it finds fraud in both its objective and subjective elements, and the failure to refer the matter to the conciliation committee does not strip the court of that power. For a founder, the message is blunt: an A1 obtained for an employee who never really worked in the home State, or kept for years beyond the posting limits, will not shield the company if the French authorities first ran the dialogue procedure and documented the sham. Genuine A1 certificates remain fully effective; decorative ones are now judicially fragile. The companion analysis of which social security applies to a foreign director and how the A1 certificate works completes this picture for the director’s own position, while the present guide covers the posted employee.

B. Regularise Now, Answer the Inspection and Challenge the Fine Step by Step

If the employee is already in France without a file, regularise today: late compliance never hurts and often halves the final amount through the good-faith assessment. File the SIPSI declaration immediately for the remaining period, designate the French representative in writing, have the core documents translated into French, top up pay to the sector minimum with overtime arrears if needed, and start genuine working-time records. Keep proof of everything with dates, because the inspector and later the court judge good faith on documents, not on promises. If URSSAF (union de recouvrement des cotisations de sécurité sociale et d’allocations familiales, the agency collecting French social contributions) opens a parallel control on contributions, treat it as a separate file with its own deadlines: winning the labour inspection does not automatically close the social-security file, and losing one file feeds the other.

When the inspector visits, the procedure is administrative and fast. Agents entitled to investigate include labour inspectors alongside tax, customs, police and social-security officers, as listed in article L8271-1-2 of the Labour Code, so a file that looks like a posting problem can quickly attract several administrations at once. Answer through the designated representative, produce the translated file at the place of work, never refuse access, and send missing items within the stated deadline with a dated cover note. Anything you declare orally should be confirmed in writing the same day; inspectors’ reports carry strong evidential weight, and an undocumented correction is treated as no correction.

If a fine is notified, read the decision letter first, not the amount. It must identify the breach, the workers concerned and the legal basis, and it opens the only appeal route that counts: the statute provides that the employer, the contractor or the client may contest the administration’s decision before the administrative court, to the exclusion of any hierarchical appeal. File a recours before the tribunal administratif (the first-instance administrative court) within the stated time limit, usually two months, and ask for interim relief only where the enforcement threatens irreversible harm, knowing that opposition to enforcement does not suspend recovery as such. From abroad, the winning arguments are concrete: the declaration was filed, even late; a representative was designated and reachable; documents were translated; pay was topped up with proof of transfer; working time is now recorded; the A1 file is genuine with home-State payslips and real prior activity. Attach bank statements, not intentions. Where several workers share one breach, argue per-worker proportionality and good faith individually, since the fine is computed per posted worker.

Paris and Île-de-France add practical specifics worth knowing. The competent inspectorate is the one where the work starts, so an employee landing at a Paris coworking space falls under the Paris unit, with the DREETS Île-de-France above it; keep the SIPSI receipt showing that unit. Paris sector minima, especially in Syntec (the tech and consulting collective agreement), commerce and construction, often exceed the statutory minimum wage, the SMIC, by a visible margin, so check the applicable convention before topping up. Translation capacity in Paris is same-day for standard payslips, which removes the usual excuse for delay. Finally, diary discipline matters more in Paris than anywhere: inspectors in the capital visit coworking spaces, trade fairs and client sites routinely, and the employee who cannot name their representative or show any French document turns a manageable file into a maximum-amount one.

Conclusion

Sending your employee to launch your French subsidiary is normal business, and French law welcomes it, on three conditions that must all be met before the first working day: a prior SIPSI declaration to the labour inspectorate, a reachable representative established in France, and a file of translated documents proving equal treatment on pay, working time and working conditions. Miss one of them and the price is an administrative fine of up to 4,000 euros per posted worker, doubled on repeat offending within two years and capped at 500,000 euros, pronounced by the administration and recoverable at once. Build the posting on a sham, an unregistered de facto establishment or decorative A1 certificates, and the file can grow into concealed work with criminal penalties, as the Court of Cassation confirmed in March 2021 for registration duties and in June 2026 for fraudulent A1 certificates set aside after the mandatory European dialogue procedure. Act in the right order from abroad instead: file late declarations immediately, appoint the representative in writing, translate the file, top up pay with proof, record working time, and contest any fine before the administrative court with dated evidence and per-worker arguments. Done this way, a posting file becomes what it should be, a launchpad for your French company rather than its first dispute.