You run your French company from London, New York, Dubai or Singapore. To keep costs down on a Paris project, you hire a subcontractor based abroad whose price beats every French quote, and a few weeks later its workers arrive on your site. Your instinct is to treat their paperwork as their problem: they are not your employees, you did not recruit them, you simply pay the subcontractor’s invoices. French labour law rejects that instinct entirely. When a foreign company posts its staff to work on your French site, you, the French client, called the donneur d’ordre when you order the service or the maître d’ouvrage when you commission the works, become a second policeman of the posting. You must check that the subcontractor filed its posting declaration on the SIPSI portal, the Système d’information sur les prestations de service internationales, which is the Ministry of Labour’s official declaration system for international service provision, you must confirm it appointed a representative in France, and if it failed either step you must file a fallback declaration yourself within forty-eight hours of the start of work. Miss these checks and the labour inspectorate, called the inspection du travail, can fine you up to 4,000 euros per posted worker, double that for a repeat offence, and the administration can suspend your project for up to one month. This guide explains, from the client’s side of the table, what to verify before the foreign team starts, what you risk when the inspector visits your site, and how to challenge a fine from abroad.

It is written for the foreign founder who already operates in France. If you are still setting up, start with our pillar guide on setting up a company in France, from the bank account and the Kbis extract to VAT and the first hire, and read our companion piece on how a foreign employer lawfully posts its own employees to France, from the SIPSI declaration to A1 certificates and fines, which covers the same operation seen from the subcontractor’s side.

I. Your French company hires a foreign subcontractor: what papers must you demand before work starts?

A. How do you verify the SIPSI posting declaration and the French representative?

Start by understanding what the subcontractor is supposed to have done, because you cannot check what you do not understand. French law defines a posted worker, called a salarié détaché, with four cumulative conditions. Article L. 1261-3 of the Labour Code, called the Code du travail, provides: “Est un salarié détaché au sens du présent titre tout salarié d’un employeur régulièrement établi et exerçant son activité hors de France et qui, travaillant habituellement pour le compte de celui-ci hors du territoire national, exécute son travail à la demande de cet employeur pendant une durée limitée sur le territoire national dans les conditions définies aux articles L. 1262-1 et L. 1262-2 .” In plain English, the worker must be employed by a company genuinely established and active outside France, must normally work for that company outside France, must work in France only for a limited time, and the operation must fit one of the legal patterns. If any of these conditions is missing, for example when the foreign company has no real activity at home and exists only to supply cheap labour to France, the operation is not a posting at all. It is undeclared work, and your vigilance duties become heavier, not lighter.

The three legal patterns are listed in article L. 1262-1 of the Labour Code: “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.” The posting is then carried out in one of three ways: for the employer’s own account and under its direction, under a service contract signed with a recipient established or operating in France, which is your situation when you hire the foreign subcontractor; between establishments of the same company or between companies of the same group, which is the intra-group posting used when your foreign parent sends staff to your French subsidiary, known as a filiale; or for the employer’s own account without any contract with a recipient. A separate provision, article L. 1262-2 of the Labour Code, covers temporary-work agencies established abroad that post agency staff to a user company in France. Ask your subcontractor, in writing, which pattern it relies on, and distrust any provider that cannot answer: a genuine posting company knows its legal basis.

Once the pattern is identified, the subcontractor must declare the posting before it starts and appoint a contact person in France. Article L. 1262-2-1 of the Labour Code states: “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 same article continues with the second duty: “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.” In practice the declaration is filed online on the SIPSI teleservice at sipsi.travail.gouv.fr, and the official procedure is described on the public service portal at entreprendre.service-public.fr, prior posting declaration and fallback declaration. Completing these two steps does not prove the posting is genuine, and the statute says so openly, but skipping them is an offence in itself, and it is the offence you as client must detect.

Your verification therefore has two concrete objects: a copy of the prior declaration sent to the labour inspectorate of the place where the work starts, and the name and contact details of the representative designated on French territory. Demand both before the first day of work, keep them in the contract file, and check their dates: a declaration filed after the start of the posting, or a representative who left France months ago, is a red flag that the provider is cutting corners. The representative matters because the foreign employer must keep the posting documents at the workplace, or failing that with its representative, and show them immediately to the inspector. Article R. 1263-1 of the Labour Code provides: “L’employeur établi hors de France conserve sur le lieu de travail du salarié détaché sur le territoire national ou, en cas d’impossibilité matérielle, dans tout autre lieu accessible à son représentant désigné en application de l’article L. 1262-2-1 et présente sans délai, à la demande de l’inspection du travail du lieu où est accomplie la prestation, les documents mentionnés au présent article.” Those documents include the employment contract or equivalent, any work permit needed for a third-country national, and proof of the pay applied. When the inspector arrives on your site and the workers cannot produce these papers through the representative, the inspector turns to you.

Add a third document to your checklist: the A1 portable certificate for each posted worker, or equivalent proof that the worker remains covered by the social security system of the home state during the posting. This is where foreign founders lose the most money. The French social security collection agency, called the URSSAF, which stands for Unions de recouvrement des cotisations de sécurité sociale et d’allocations familiales, systematically reassesses the French contributions of posted workers whose home-state coverage is not proven, and the courts back it. In a ruling of 16 October 2025, appeal number 23-14.039, the Second Civil Chamber of the Court of Cassation quashed an appeal decision that had cancelled such a reassessment, holding: “alors qu’à défaut de production de documents justifiant du rattachement des salariés de la société travaillant sur le sol français à la législation de leur pays d’origine, le redressement était justifié”, which means that where the employer produces no document proving its workers on French soil remain affiliated to their home country’s legislation, the reassessment stands. The European framework behind the A1 certificate is Regulation (EC) No 883/2004 on the coordination of social security systems. Ask for a copy of every A1 before work starts, check that the names, dates and posting period match the SIPSI declaration, and refuse to let workers on site whose certificates are missing or expired: an A1 that does not cover the actual posting period protects nobody.

All of this sits on top of your general duty of vigilance toward every contractor, French or foreign. Article L. 8222-1 of the Labour Code provides: “Toute personne vérifie lors de la conclusion d’un contrat dont l’objet porte sur une obligation d’un montant minimum en vue de l’exécution d’un travail, de la fourniture d’une prestation de services ou de l’accomplissement d’un acte de commerce, et périodiquement jusqu’à la fin de l’exécution du contrat, que son cocontractant s’acquitte : 1° des formalités mentionnées aux articles L. 8221-3 et L. 8221-5”, which are the declaration and registration formalities that prove the contractor is not operating off the books. The verification must be repeated periodically until the end of the contract, not done once and forgotten. For posted workers specifically, the client’s duty is spelled out even more directly. Article L. 1262-4-1 of the Labour Code provides: “Le donneur d’ordre ou le maître d’ouvrage qui contracte avec un prestataire de services qui détache des salariés, dans les conditions mentionnées aux articles L. 1262-1 et L. 1262-2 , vérifie auprès de ce dernier, avant le début du détachement, qu’il s’est acquitté des obligations mentionnées aux I et II de l’article L. 1262-2-1 .” That is the declaration and the representative, verified before the posting begins. Put the clause in your subcontract: delivery of the SIPSI declaration receipt, the representative’s details, valid A1 certificates and proof of registration in the home state, as conditions precedent to site access, with a right to suspend payment and access until complete. A subcontractor that refuses these papers in writing has told you everything you need to know.

B. What if the subcontractor never sent the declaration: the 48-hour rule that saves you?

The statute anticipates the dishonest or careless provider. If your subcontractor did not give you a copy of its prior declaration, you must file one yourself, and fast. Article L. 1262-4-1 of the Labour Code continues: “A défaut de s’être fait remettre par son cocontractant une copie de la déclaration mentionnée au I de l’article L. 1262-2-1, le maître d’ouvrage ou le donneur d’ordre adresse, dans les quarante-huit heures suivant le début du détachement, une déclaration à l’inspection du travail du lieu où débute la prestation.” Forty-eight hours from the start of the posting, to the labour inspectorate of the place where the service begins. This fallback declaration, called the déclaration subsidiaire, is your legal lifeboat: it does not cure the subcontractor’s breach, but it proves that you performed your own duty and it shields you from the client-side fine described below. In practice, designate one person in your French company, or your French counsel, as the owner of this deadline, with a standing instruction that no foreign team starts work on Friday afternoon without the papers, because the forty-eight hours include the weekend and the inspector counts calendar hours, not business days you find convenient.

Build the compliance file the same day. Keep together the service contract, the SIPSI declaration or your fallback declaration with proof of sending, the representative’s appointment, the A1 certificates, the workers’ pay records showing the hourly rates applied in France, and the correspondence in which you requested the documents. France guarantees posted workers equal treatment with employees of companies in the same sector established in France on a hard core of subjects including pay, working time and safety. The principle is stated in article L. 1262-4 of the Labour Code, and it means the bargain price of your subcontract cannot be built on paying posted workers below the French minimum wage, called the SMIC, or below the sector collective agreement, nor on working-time arrangements that French law would forbid. You are not the employer, so you do not set their pay, but if the inspector finds posted workers on your site paid manifestly below French minima, the investigation widens to your vigilance file, and an empty file suggests you chose the provider for its lawlessness. Ask for the hourly rates in the declaration data and compare them with the French minima for the sector: a rate that cannot possibly fund a lawful posting is information, and ignoring information is negligence.

Construction and public-works founders should add one more check: workers posted to building or civil-engineering sites must hold the BTP identification card, called the carte BTP, and the declaration procedure is described on the public service portal at entreprendre.service-public.fr, BTP card for posted workers. On a Paris-region site, where joint inspections by the labour inspectorate, the URSSAF and the police are routine, a team without BTP cards is stopped within hours, and your project stops with it.

Finally, resist the temptation that destroys more files than any missing form: directing the posted workers yourself. When your site manager gives them daily orders, sets their hours, grants their leave and disciplines them, while the foreign subcontractor fades into a mere payroll office, the workers acquire a French employer, which is you. The Court of Cassation polices this boundary in both directions. In a Social Chamber ruling of 5 April 2023, appeal number 21-21.318, concerning an Italian employee posted for over twenty years to a French economic interest grouping, the court approved the appeal judges who had refused to recognise an employment contract with the French host, holding: “En l’état de ces constatations, la cour d’appel a pu déduire l’absence de contrat de travail liant le salarié au GIE ATR.” The decisive findings were that pay, promotions and the long-service medal came from the Italian company, that the recall order and the dismissal for serious misconduct came from the Italian employer, and that the daily instructions of the French host were inherent to performing a posting mission rather than proof of a relationship of subordination, called the lien de subordination, with the host. Read from the client’s side, the lesson is symmetrical: keep the subcontractor visibly in charge. Its supervisor gives the orders, its company issues the payslips, its management handles discipline, and your instructions pass through its chain of command. The day your foreman starts signing the posted workers’ leave requests, you are writing their future claim for a French employment contract, with back pay, severance and damages attached.

II. Labour inspection on your site, fine or shutdown: what do you risk and how do you fight back?

A. How much can the fine and the suspension of your project cost you?

Controls usually start without warning: two inspectors arrive on site, ask the workers who employs them, demand the posting documents, and when the papers are missing, interview you as the client. The fines that follow are administrative, imposed by the regional authority, which is the DREETS, the Direction régionale de l’économie, de l’emploi, du travail et des solidarités, on the report of the inspector, and they apply to you as client independently of whatever the subcontractor receives. Article L. 1264-2 of the Labour Code targets the project owner, the client and the user company: “Le maître d’ouvrage, le donneur d’ordre ou l’entreprise utilisatrice est passible d’une amende administrative, dans les conditions prévues à l’article L. 1264-3 : 1° En cas de méconnaissance d’une des obligations mentionnées au I de l’article L. 1262-4-1 , lorsque son cocontractant n’a pas rempli au moins l’une des obligations lui incombant en application de l’article L. 1262-2-1”, which is exactly your failure to verify the declaration and the representative, or to file the fallback declaration within forty-eight hours. The amounts are set by article L. 1264-3 of the Labour Code: “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 €.” Ten posted workers without papers therefore expose you to 40,000 euros on a first finding, 80,000 on a repeat finding within two years, capped at 500,000 euros per decision. The same article fixes the limitation period: “Le délai de prescription de l’action de l’administration pour la sanction du manquement par une amende administrative est de deux années révolues à compter du jour où le manquement a été commis.” Two full years from the day of the breach, which means a posting that ended last year can still produce a fine today.

For comparison, the foreign employer’s own scale is heavier on some breaches: ignoring an administrative suspension or formal demand order costs up to 10,000 euros per worker concerned. Article L. 1263-6 of the Labour Code provides: “L’amende est inférieure ou égale à 10 000 € par salarié concerné par le manquement.” Knowing both scales helps you negotiate with your provider: when you demand the papers, you can point out that its exposure exceeds yours, and a serious provider will comply rather than argue.

Beyond money, the administration can stop your project. If the employer does not regularise after a formal demand, the authority may order the suspension of the service for up to one month. Article L. 1263-4 of the Labour Code provides: “l’autorité administrative compétente peut, dès lors qu’elle a connaissance d’un rapport d’un agent de contrôle de l’inspection du travail constatant le manquement et eu égard à la répétition ou à la gravité des faits constatés, ordonner, par décision motivée, la suspension par l’employeur de la réalisation de la prestation de services concernée pour une durée ne pouvant excéder un mois.” The suspension technically targets the provider’s service, but the concrete effect lands on you: the foreign team leaves your site, your schedule slips, your own client applies delay penalties, and you pay a replacement crew at emergency rates. The authority lifts the measure as soon as the breach ends, which is another reason to hold copies of every document yourself: you can push the provider to regularise within hours instead of discovering the file is empty when the order arrives. In Paris and the Île-de-France region, where the DREETS territorial units coordinate joint operations on large sites and on subcontracting chains in construction, renovation and logistics, suspensions are not theoretical. Founders who run works in Paris should therefore integrate a specific Paris and Île-de-France reflex into the project plan: identify in advance which inspectorate covers the site’s arrondissement or département, keep the fallback declaration channel ready before the team arrives, and prepare the documents the Paris units ask for first, namely the SIPSI receipt, the representative’s details and the A1 certificates.

The third bill can come from the URSSAF. If the posted workers’ home-state coverage collapses, because the A1 certificates were never issued, were withdrawn by the home institution, or never matched the actual posting, the URSSAF reassesses the French social contributions on their wages, and the amounts dwarf the administrative fines. The Court of Cassation’s 16 October 2025 ruling quoted above is the authority to remember: without documents proving affiliation to the home legislation, the reassessment stands. As client you do not pay the provider’s contributions, but a provider hit with a six-figure reassessment often defaults, abandons the site, or passes the cost back through disputed invoices, and your project absorbs the shock. Checking the A1 certificates before work starts is therefore not administrative courtesy. It is counterparty-risk management.

B. How do you challenge the fine before the administrative court and protect the project?

Every fine decision can be challenged, and the forum is fixed by statute: the administrative court, with no hierarchical appeal to the minister. Article L. 1264-3 of the Labour Code states: “L’employeur, le maître d’ouvrage ou le donneur d’ordre peut contester la décision de l’administration devant le tribunal administratif, à l’exclusion de tout recours hiérarchique.” The general time limit for seizing the administrative court is two months from notification of the decision. Article R. 421-1 of the Code of Administrative Justice, called the Code de justice administrative, provides: “La juridiction ne peut être saisie que par voie de recours formé contre une décision, et ce, dans les deux mois à partir de la notification ou de la publication de la décision attaquée.” Two months is short when you live abroad, receive the letter at your French registered office, called the siège social, and need translations, evidence from the provider’s home country and a lawyer admitted to the administrative courts. Diary the deadline the day the registered letter arrives, and instruct counsel immediately; founders who call for help in the final week, for example at +33 6 46 60 58 22, regularly discover that the essential proof, a dated SIPSI receipt or a valid A1, takes longer to obtain from the provider than the remaining days allow.

Do not count on the appeal to freeze payment. The statute organises recovery as for state debts unrelated to tax and provides expressly that objections to enforcement do not suspend collection. Article L. 1264-3 of the Labour Code states: “L’amende est recouvrée comme les créances de l’Etat étrangères à l’impôt et au domaine. L’opposition à l’exécution ou l’opposition aux poursuites n’a pas pour effet de suspendre l’action en recouvrement de la créance.” In practice you must therefore run two tracks at once: challenge the fine on the merits before the administrative court, and separately apply for interim relief, called the référé-suspension, if payment or the reputational stain would cause consequences that are hard to reverse. Interim relief requires an urgent situation and a serious doubt about legality, and it is granted sparingly, so the main battle remains the merits.

On the merits, the administration must prove the breach, but your file does most of the talking. Judges check, in order, whether the workers were genuinely posted or were in fact your disguised workforce, whether the declaration and representative duties were fulfilled and by whom, whether you filed the fallback declaration within forty-eight hours when the provider defaulted, and whether the amount reflects the circumstances, your good faith, your resources and your liabilities, since the statute expressly lists good faith among the sentencing factors. Your winning exhibits are therefore the dated SIPSI declaration or your fallback declaration with transmission proof, the representative’s appointment, the A1 certificates covering the exact posting period, the subcontract’s vigilance clause and your written requests for documents, the pay records showing French minima were met, and any evidence that you stopped site access until the papers arrived. Conversely, the file that loses is the familiar one: no written request before the control, a declaration filed the day after the inspectors came, A1 certificates requested retroactively, and a site manager who directed the workers daily, which invites the requalification argument described above. If the provider supplied false documents, say so with evidence and join the provider to the proceedings where possible, but do not present yourself as a victim who checked nothing: the offence punishes precisely the failure to check.

Parallel to the court case, secure the project. Replace a defaulting provider only after documenting the default by formal notice, called the mise en demeure, because terminating a service contract without cause exposes you to damages that compound the fine. For the replacement provider, apply the full part I checklist from day one, and consider requiring a bank guarantee or a retention on invoices covering the posting-compliance risk. If a suspension order hits, regularise immediately and seek its lifting in writing with the complete file: the authority ends the measure as soon as the breach ceases, and every day saved is a day of delay penalties avoided. Keep the commercial register extract of your French company, called the extrait Kbis, which is the official identity card of a French company issued by the court clerk, called the greffe, and your filings with the trade register up to date throughout, since an inspector who finds a company whose Kbis, representative and site paperwork are all in order starts from the assumption of good faith. That assumption is worth more than any argument.

Conclusion

Hiring a foreign subcontractor to work on your French site does not outsource legal responsibility. It creates a shared compliance chain in which you are the link the inspector sees first. Demand the SIPSI declaration and the French representative’s details before work starts, collect valid A1 certificates covering the exact posting period, file your own declaration within forty-eight hours whenever the provider defaults, never direct the posted workers as if they were your staff, and keep every proof in a file you can produce on the spot. These five reflexes cost a few hours of preparation and they neutralise fines of up to 4,000 euros per worker, a suspension that can freeze your project for a month, and a URSSAF reassessment that can sink your provider and delay your works. The posting rules are strict, but they are also entirely predictable: the client who checks, declares and documents has nothing to fear from the inspection, and every argument it needs before the administrative court.