You run your company from London, New York, Dubai or Singapore. A client in Paris needs your engineer on site for six weeks, or your group wants one of its managers to spend three months setting up the French operation. You book the flight, you keep paying the salary from the home payroll, and you assume nothing changes because the employment contract stays foreign. In France, that assignment has a legal name, a prior declaration, a social-security certificate, a local contact person, and a scale of fines that applies per worker. The mechanism is called posting of workers, known in French as détachement, and it is one of the most inspected topics in French labour law. The labour inspector, called the inspection du travail, can walk onto the Paris site, ask for two documents, and start a fine procedure on the spot if either is missing. This article explains, for a foreign business owner or manager who stays abroad, what must be filed before the first day of work in France, which French pay and working-time rules apply from day one, what the courts have actually decided when companies got it wrong, and how to repair a missing filing once the inspection has already come. Every French acronym is explained, every decisive rule is linked to its official text, and the two court decisions cited are quoted word for word.

I. Before the first day of work in France, two filings decide everything

A. Can you send your employee to France, and have you declared the posting on SIPSI?

French law starts from a permissive principle. An employer established outside France may temporarily post employees to French territory, provided an employment contract exists between that employer and the employee and the employment relationship continues during the posting period. The exact statutory sentence reads: “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.” That is Article L. 1262-1 of the French Labour Code (Code du travail), verified in force on 11 October 2026. Three posting patterns are covered: work performed for your own account under your direction within a contract with a French client, movement between establishments of the same company or group, and work for your own account with no French client at all, such as sending a manager to prepare a French subsidiary. If you are still hesitating between creating a French company, opening a branch office (succursale), or simply sending staff from abroad, read first the companion guide on choosing between a SAS, a SARL, a branch and a subsidiary in France, because posting only works while the employment relationship genuinely stays with the foreign employer.

The permission comes with a prior formality that has no grace period. Before the posting starts, the foreign employer must send a declaration to the labour inspector of the place where the work begins. The statute 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.” That is Article L. 1262-2-1 of the Labour Code. In practice this declaration is filed online on SIPSI, the posting declaration portal (télé-service SIPSI) of the Ministry of Labour, and the portal issues an acknowledgement of receipt, called accusé de réception. Keep that receipt: it is the first document the inspector asks for, and the French client is legally required to ask you for it before the work starts, as Article R. 1263-12 of the Labour Code makes the client request the SIPSI acknowledgement plus a sworn statement (attestation sur l’honneur) on fine payments. The Ministry of Labour describes the portal and the procedure on its official pages SIPSI, prior declaration of posting and mandatory prior formalities for posting employees in France, both available in English.

The same article imposes a second obligation that foreign managers often discover too late: the posting employer must appoint a representative of the company on French territory, a contact person responsible for liaising with the inspection services for the whole duration of the work. The statute states that the employer designates this representative, charged with liaison with the inspection officers during the assignment. This person does not need to be an employee of the group; it can be a local adviser or service provider with a real address, reachable quickly, holding copies of the SIPSI receipt, the A1 certificate, pay records and the employment contract translated where needed. An inspector who cannot reach anyone in France treats the file as uncooperative, and the fine procedure moves faster. For a posting in Paris or anywhere in the Paris region (Île-de-France), the competent inspector is the one for the place where the service starts, which for most foreign companies means the Paris labour inspection unit (unité de contrôle) covering the arrondissement of the client site. File the declaration early enough that the acknowledgement exists before the employee boards the plane, name a representative who actually answers the phone, and send both documents to the French client in writing before day one, because the client faces its own fine if your declaration is missing.

One warning that saves expensive misunderstandings: completing the SIPSI declaration and appointing the representative does not prove the posting is genuine. The statute says expressly that performing these duties does not presume the posting is lawful. If the employee in fact works permanently in France under the direction of the French client, with no real link to the foreign employer, the authorities reclassify the arrangement as undeclared work (travail dissimulé) or as direct employment by a French entity that should have registered with URSSAF, the French social-security collection agency, and filed a prior hiring declaration (DPAE, déclaration préalable à l’embauche). The declaration protects a genuine posting; it never launders a permanent job. Companies that use foreign service providers or freelancers on site face the mirror risk: if the contractor is really an employee, the reclassification analysis described in the companion article on contractor reclassification and URSSAF reassessment applies in full.

B. Is your employee still covered by home social security, and can you prove it with an A1?

Labour law is only half the file. The other half is social security: which country collects contributions on the salary earned during the French assignment. The default European rule is that a person working in a Member State is subject to that State’s legislation, but postings benefit from a narrow exception. Under Article 12 of Regulation (EC) No 883/2004 of 29 April 2004 on the coordination of social security systems, a person employed in one Member State who is sent by the employer to another Member State to perform work there for that employer remains subject to the home legislation, provided the anticipated duration does not exceed twenty-four months and the person is not sent to replace another posted person. The proof of that exception is a portable document called the A1 certificate (formerly E101), issued by the home social-security institution, stating that the worker stays affiliated at home. Without an A1, the French position is simple: the worker on French soil falls under French affiliation, URSSAF contributions are due in France, and the separate URSSAF audit procedure, with reassessment (redressement) and penalties, can start. Foreign groups already operating a French company know that procedure from the companion guide on URSSAF audits, assessments and challenges from abroad; for posted workers the same logic applies one step earlier, at the border of affiliation.

Request the A1 from the home institution weeks before departure, because processing times vary widely between countries and the inspector asks for it on day one alongside the SIPSI receipt. Check three points on the certificate itself: the exact identity of the worker, the exact French assignment dates, and the identity of the posting employer, because a certificate naming a different entity or expired dates is treated as no certificate. Keep the original or a certified copy with the representative in France and a digital copy with the home HR team. If the assignment extends beyond twenty-four months, do not assume silence extends coverage: an extension requires an agreement between the institutions (Article 16 exception procedure), and without it French affiliation starts. For assignments from outside the European Union, no A1 exists; coverage depends on the bilateral social-security agreement between France and the country concerned, and where none exists, French affiliation and registration obligations generally apply from the first day, which usually means the posting model must give way to direct French hiring with a DPAE filed under Article L. 1221-10 of the Labour Code, providing that hiring may only occur after a nominative declaration to the social-protection bodies.

The legal force of the A1 certificate is the point on which two published decisions of the Cour de cassation, France’s supreme court for civil and criminal matters, give foreign employers both a shield and a warning. The shield comes from Criminal Chamber, 18 September 2018, No. 13-88.631 (Air France and CityJet), published in the Bulletin. The Irish subsidiary CityJet had staff working at Roissy and Orly airports, and the French courts had convicted the parent company of complicity in undeclared work for missing social-security declarations. The Criminal Chamber quashed the conviction, holding that the court could not set aside the E101 certificates, now A1, without first following the fraud procedure defined by the Court of Justice of the European Union: “elle ne pouvait écarter les certificats E101 sans avoir, au préalable, recherché si l’institution émettrice desdits certificats avait été saisie d’une demande de réexamen et de retrait de ceux-ci sur la base des éléments concrets recueillis dans le cadre de l’enquête judiciaire permettant, le cas échéant, de constater que ces certificats avaient été obtenus ou invoqués de manière frauduleuse”. In plain terms, a court must respect an A1 certificate unless the issuing institution was asked to review and withdraw it on concrete evidence and failed to act within a reasonable time, and unless fraud by the employer is then proven with respect for fair-trial guarantees. For a compliant foreign employer, that holding is powerful: a genuine A1, obtained honestly, blocks the criminal reclassification into undeclared work.

The warning comes from Social Chamber, 4 November 2020, Nos. 18-24.451 and others (Bouygues Travaux Publics), published in the Bulletin and the Report. Posted workers supplied by a foreign temporary-work agency had no A1 or E101 certificates, and the French user company, informed of the irregularity, had not forced its contractor to regularise. The Social Chamber rejected the appeal and confirmed the French user’s joint liability for undeclared-work indemnities, stating: “il appartient à l’entreprise utilisatrice, informée de l’intervention de salariés, employés par une entreprise de travail temporaire, en situation irrégulière au regard des formalités mentionnées aux articles L. 8221-3 et L. 8221-5 de ce code, d’enjoindre aussitôt à celle-ci de faire cesser sans délai cette situation.” Failing that immediate order to stop the irregularity, the user company pays jointly with the foreign agency. Read from abroad, the lesson is symmetrical: hold a genuine A1 and the supreme court protects you; have none, and both you and your French client pay. The A1 is therefore not an administrative nicety but the document that decides whether a posting dispute stays an inspection file or becomes a criminal and damages file.

II. While the inspector checks your file from Paris, French pay rules and fines already apply

A. Does your posted employee cost as much as a French employee from day one?

Yes, and this is the point that destroys most budgets built abroad. A posted worker must receive equal treatment with employees of companies in the same sector established in France, covering the matters French law lists. Article L. 1262-4 of the Labour Code guarantees that equality across individual and collective freedoms, discrimination and gender equality, maternity and family leave, the right to strike, working time, compensatory rest, public holidays, paid leave, submission to leave funds, remuneration within the meaning of equal-pay rules including overtime premiums, health and safety, illegal work, and reimbursement of detached-worker travel, meal and accommodation expenses. Since the 2020 reform transposing the revised Posting Directive, the reference is no longer a minimum floor but full remuneration as defined by the sector rules applicable in France, which includes the sector collective agreement (convention collective) in force for the activity concerned. A German engineer posted to a Paris construction site is therefore paid under the construction sector pay scales, a Spanish consultant posted to a French bank under the banking agreement, each with the applicable overtime premiums. The French 35-hour week (durée légale de 35 heures) is the baseline: hours beyond it carry statutory premiums, typically 25 percent for the first eight overtime hours and 50 percent beyond, unless the applicable agreement sets different rates, and the posted worker’s schedule must respect French maximum working times, daily and weekly rest, and paid-leave accrual. Foreign employers who already run French payroll know these mechanics from the companion analysis of overtime, time records and labour-court proof for the first French hire; every line of that analysis applies to posted workers too, from the first posted day.

Concretely, before the assignment, obtain the applicable French sector agreement, identify the coefficient or level matching the posted worker’s duties, and compute the French remuneration for the assignment period including overtime premiums, night or Sunday premiums where relevant, and the travel, meal and accommodation reimbursements the statute lists separately. If the home salary already exceeds that French reference, document the comparison job by job and month by month, because the inspector compares amounts actually paid against the French scale and asks for proof, not assertions. Keep in France, with the liaison representative, the documents an inspector routinely demands: the SIPSI receipt, the A1, the employment contract, recent payslips, working-time records (décompte du temps de travail) showing daily hours, and the sector agreement reference applied. Payslips (bulletins de paie) must allow the inspector to verify the overtime premiums; a single monthly lump sum labelled bonus, with no hour count, fails the check and supports a minimum-wage or overtime claim later before the labour court (conseil de prud’hommes). Where the posting exceeds twelve months, a second layer applies: the posted worker gains the benefit of nearly all applicable French labour provisions beyond the listed core, with a possible reasoned extension to eighteen months, so long assignments must be re-examined as they approach the one-year mark rather than left to run.

Two practical traps deserve emphasis because they generate most disputes. First, accommodation and travel costs: sums paid to reimburse posting-specific expenses must be identifiable as such and cannot be counted as salary to reach the French pay level, while flat allowances that do not correspond to real expenses may be reclassified as salary, changing both the pay comparison and the contribution base. Structure the assignment letter to separate salary, posting allowances and genuine expense reimbursements, with receipts. Second, paid leave: posted workers accrue French-law leave rights during the assignment, and sectors with leave funds (caisses de congés), notably construction, require affiliation and contributions for the posting period. An employer who ignores the leave fund receives both the fund’s recovery claim and an inspection finding, and the amounts compound quickly across a team. Finally, remember that health and safety rules apply in full on French territory: risk assessment for the French site, safety training in a language the worker understands, and protective equipment where the activity requires it. An accident involving a posted worker triggers the French accident-at-work declaration chain and the liability analysis of the French host, which is not the file in which to discover that nobody knew who the safety contact was.

B. What does the inspection fine, who else pays, and how do you repair a missing filing?

The sanction scale is administrative, per worker, and cumulative across findings. Breach by the posting employer of the SIPSI declaration, the liaison representative, related information duties or document obligations exposes the employer to an administrative fine under Article L. 1264-1 of the Labour Code, pronounced under the conditions of Article L. 1264-3, which states: “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 €.” Four thousand euros per posted worker, eight thousand for a repeat within two years, capped at five hundred thousand euros per procedure, with the amount set according to the circumstances, the seriousness, the behaviour of the offender including good faith, and its resources. The limitation period is two full years from the breach, and the decision can be challenged before the administrative court (tribunal administratif), with no hierarchical appeal. Parallel fine tracks exist for working-time, rest, time-record and minimum-pay breaches under the inspection fine regime, and the criminal track for undeclared work remains available to the prosecutor where the facts show intentional evasion of declarations, as the Air France and CityJet prosecution recalled. A missing SIPSI receipt for a team of ten therefore opens a file worth up to forty thousand euros before any other head of fine, and a missing A1 adds the contribution reassessment on top.

The fine does not stop at the foreign employer. The French client, project owner (maître d’ouvrage) or ordering party (donneur d’ordre) that uses your posted workers must verify your SIPSI receipt before the work starts and faces its own administrative fine if you have filed nothing. The verification duty sits in Article R. 1263-12, and the client-side fine in the L. 1264-2 chain. Beyond fines, the client carries the joint financial liability (solidarité financière) confirmed by the Bouygues decision: once informed in writing that your workers are in an irregular situation regarding hiring declarations and payslips, the client must immediately order you to stop the irregularity. The statute commands: “enjoint aussitôt à son cocontractant de faire cesser sans délai cette situation.” That is Article L. 8222-5 of the Labour Code. Failing that order, the client pays jointly with you the taxes, contributions, wages and undeclared-work indemnities. Expect a serious French client, especially a large group or a public-sector buyer, to demand your SIPSI receipt and A1 copies in the contract and to suspend your workers’ site access the day an inspector raises a question. Build that document flow into the service agreement itself: a clause requiring transmission of the SIPSI acknowledgement and valid A1 certificates before mobilisation, monthly confirmation of continued validity, and immediate notice of any inspection visit. The clause protects both sides and shortens every dispute.

If the inspection has already visited and the filing was missing, work through the repair sequence in this order. First, within days, file the SIPSI declaration for the ongoing and future posting periods and appoint the liaison representative if none was named; late filing does not erase the breach for the elapsed period, but it stops the daily accumulation, demonstrates good faith that the fining authority must weigh, and restores the client’s verification file. Second, apply immediately for the A1 certificates for the workers concerned, or, where the home country has no procedure covering the situation, seek advice on switching the affected workers to French affiliation and registration rather than letting an uncovered period grow. Third, reconstruct the pay comparison against the French sector scale for the whole assignment and pay any shortfall as salary with corrected payslips before the inspector’s report closes, because a spontaneous back-payment documented in the file reduces both the fine and the later labour-court exposure. Fourth, answer the inspector’s letters within the stated deadlines, in French, through the liaison representative, attaching each document in an indexed bundle; silence is recorded as such in the report. Fifth, calendar the appeal: a fine notification states the remedies and time limits, and the challenge goes to the administrative court, so have counsel review the notification on receipt rather than after the deadline. Where the facts suggest the arrangement was never a genuine posting, for example a worker permanently integrated into the French client’s teams, the honest repair is different: stop new postings, register the French presence properly, whether by incorporating a company through the route compared in the SAS, SARL, branch and subsidiary guide, and regularise the workers’ status, because persisting in a reclassified posting converts an administrative file into a criminal one.

Conclusion

Sending an employee to work in France while you remain abroad is lawful, routine and well protected when two documents exist before day one: the SIPSI prior declaration with a reachable French liaison contact, and a genuine A1 certificate keeping the worker under home social security for up to twenty-four months. From the first hour on French soil, French sector pay scales, overtime premiums, working-time limits and safety rules apply in full, and the supreme court’s published decisions draw the boundary with unusual clarity: an honestly obtained A1 must be respected by the criminal court unless a formal fraud procedure overturns it, while the absence of certificates makes both the foreign employer and the French client pay jointly. The administrative fine of up to four thousand euros per worker, doubled on repeat offending, prices every missing receipt. Foreign founders who treat the posting as a small logistical detail discover its cost at the inspection; those who file early, compute the French pay comparison before departure, and keep the document bundle with a real contact in France turn a high-risk assignment into an ordinary business trip. The posting is temporary by definition, so diary the end date as carefully as the start: extend, renew or settle permanently in France only through a deliberate new step, with fresh filings to match.