The French construction market is one of the most dynamic in Europe. Every year, thousands of European companies-German, Belgian, Italian, Spanish, Portuguese, Polish-seek to win contracts on French territory.

But between signing the first contract and striking the first hammer blow, an administrative obstacle course awaits. The number one roadblock? Decennial civil liability insurance (assurance décennale)-the mandatory guarantee that protects the client (the project owner) for 10 years after the completion of the works.

Without this insurance, there is no construction site. And to obtain it, insurance companies require documents that many foreign contractors simply do not have: a Kbis extract (certificate of incorporation), a SIRET number, and proof of legal establishment in France.

This comprehensive guide walks you step-by-step through the process, from registering your branch office in France to sending your workers to the site, including tax implications and posted worker obligations.

1. “My French insurer is asking for a SIRET number”: What to do?

The SIRET (Système d’Identification du Répertoire des Établissements) is the unique 14-digit registration number assigned to every establishment in France to prove legal existence on the territory. The Kbis extract, on the other hand, is essentially your company’s “official ID card” in France, issued by the Commercial Court.

Why does the insurer require these documents?

Decennial insurance is a massive financial commitment for the insurer. The Spinetta Law (Law No. 78-12 of January 4, 1978) imposes a presumption of liability on the builder for 10 years. In the event of a major defect (affecting the solidity of the structure or making it unfit for its intended use), the insurer will have to pay-sometimes hundreds of thousands of euros.

To grant this level of trust, insurance companies rigorously verify:

• That your company has a verifiable legal existence in France (SIRET + Kbis).
• That you have proven experience in the specific works you intend to perform.
• That your financial capacity is sufficient (annual accounts of your parent company).
• That you do not have an history of major claims.

Why isn’t a “virtual office” or a simple P.O. Box enough?

Many foreign companies think they have found a quick fix: renting a cheap domiciliation address online-a simple mailbox in a Parisian building or an accommodation address.

This is a dead end. Here is why:

• Insurers’ compliance departments verify the reality of your establishment. An address shared by 200 companies with no real activity is an immediate red flag.
• To obtain a valid Kbis, the Commercial Court or the INPI requires that your domiciliation complies with the provisions of Article L.123-11-1 of the Commercial Code-meaning the address must correspond to real commercial premises with a proper domiciliation contract.
• A simple postal address without a compliant commercial domiciliation contract will be rejected during registration or will lead to your company being struck off the register.

2. How to get a SIRET in France as a foreign company?

The good news is that you do not need to create a brand new French company (such as a SASU, SARL, or SAS) with share capital, articles of association drafted by a lawyer, and all the administrative burdens that entails.

The legal solution: Opening a branch office in France

The most efficient and lightweight way to obtain a SIRET is to open a branch office (succursale) of your foreign parent company in France.

What exactly is a branch office?

A branch office (also known as a secondary establishment) is a direct extension of your parent company (German, Spanish, Portuguese, etc.) in France. It:

• Does not have its own legal personality: your parent company remains the decision-maker and legally liable entity.
• Has its own SIRET number: it is registered with the RCS (Trade and Companies Register) and generates a French Kbis extract.
• Can engage in commercial activity in France: invoice clients, respond to calls for tenders, and subscribe to insurance policies.

Should you create a subsidiary (SASU, SARL) instead?

No, unless you need a completely independent structure with its own share capital and governance. For the vast majority of construction companies simply wishing to obtain decennial insurance and work on French sites, the branch office is more than sufficient and offers several advantages:

Concrete steps to register your branch office

1. Obtain a compliant commercial domiciliation address in France (this is where Altaleo comes in-see below).
2. Gather required documents: translated articles of association of the parent company, power of attorney for the legal representative, ID of the director, proof of headquarters abroad.
3. Submit the application to the INPI (the single portal for company formalities) or the relevant Commercial Court registry.
4. Receive your French Kbis extract within a few weeks, which will contain your SIRET number.

3. What documents to provide to the insurer for the decennial guarantee?

Once your branch is registered and your Kbis is in hand, you can finally submit an application to a decennial insurance company. Here is what they will ask for:

Required documents list

• French Kbis extract (less than 3 months old) of your branch.
• Proof of professional experience: invoices and/or contracts justifying a minimum of 2 to 3 years of activity in your home country, in the trades you wish to cover.
• Professional qualifications of your artisans and workers: diplomas, qualification certificates (recognized artisan title in your home country), training certificates.
• Financial statements of your parent company: the last 2 or 3 accounting years, to prove the company’s solid financial standing.
• Certificate of non-claim (attestation de non-sinistralité): a document-often issued by your original insurer-proving that your company has not been subject to major decennial claims in recent years.
• Detailed description of activities you will perform in France (structural work, finishing, electricity, plumbing, etc.), along with projected revenue.

How long does it take to get decennial insurance?

The timeframe varies depending on the brokers and insurers, but you should generally expect:

• 1 to 3 weeks to compile the complete file (if all documents are readily available).
• 2 to 6 weeks for the insurer to study the file and issue the insurance certificate.

In total, plan for 1 to 2 months between submitting your application and receiving your decennial insurance certificate. An incomplete file or untranslated documents will significantly extend this timeframe.

Is my home country’s decennial insurance valid in France?

This is a common question. The answer is nuanced:

• In theory, the European principle of freedom to provide services (Directive 2006/123/EC) allows an EU company to provide a decennial guarantee underwritten in another Member State, provided that this guarantee offers an equivalent level of protection to French law.
• In practice, most French clients, architects, and project managers demand a decennial insurance underwritten by an insurer licensed in France, as coverage conditions vary wildly from one country to another.
• Our recommendation: even if your foreign insurance theoretically covers the 10-year liability, it is highly advisable to take out a specific policy in France to avoid any disputes or site entry refusals.

4. What are the tax implications of a branch office in France?

Registering in France is not just an administrative formality. Opening a branch creates what the tax authorities call a “permanent establishment” (établissement stable) under Article 209-I of the General Tax Code. This triggers tax obligations you must anticipate.

French VAT: Do you need to charge VAT?

Your branch will receive a French intra-community VAT number. VAT rules in construction are as follows:

• For B2C work (residential clients): you must invoice with French VAT at the applicable rate (generally 20%, occasionally 10% for renovations on homes over 2 years old, or 5.5% for energy-efficiency upgrades).
• For B2B subcontracting work: the VAT reverse-charge mechanism (autoliquidation) often applies (Article 283-2 nonies of the CGI). The main contractor declares the VAT themselves.
• This VAT must be declared periodically to the French tax administration (monthly or quarterly CA3 return).

Corporate Income Tax (IS)

Since your branch constitutes a permanent establishment, the profits generated by your activity on French soil will be subject to French Corporate Tax (IS). The standard corporate tax rate in France is 25%.

Note: bilateral tax treaties between France and your home country provide mechanisms to avoid double taxation. Generally, profits attributable to the French branch are taxed in France, and your parent company receives a corresponding tax credit back home.

Local Business Taxes (CFE)

Depending on your domiciliation location, your branch will also be liable for the CFE (Contribution Foncière des Entreprises), a local business tax calculated based on the rental value of your premises.

5. How to legally send your workers to French construction sites?

Your branch is registered, your decennial insurance is signed. It is time to send your teams to the field. But beware: the posting of workers in the French construction sector is the most heavily inspected in Europe. The construction sector is classified as “high risk” by the Labor Inspectorate, and site inspections are frequent and unannounced.

What is the posting of workers?

Since your branch has no separate legal personality, your workers keep their original employment contract. When they come to work temporarily in France, they are considered posted workers under the European Directive 96/71/EC, revised by Directive 2018/957/EC, and transposed into the French Labor Code.

The mandatory SIPSI prior declaration

Before the start of any assignment on a site, you must strictly register each posted worker on the French government’s online portal, SIPSI (sipsi.travail.gouv.fr).

How to do it:

1. Create an account on sipsi.travail.gouv.fr.
2. Enter your company information (contact details, SIRET, country of origin).
3. For each posting, declare: the French client (with their SIRET), the work location(s), the identity of each worker, the salary paid, their professional qualification, and their accommodation details.
4. Safely store the declaration receipt (acknowledgment): this is the document you must present during a site inspection.

The A1 Form: Proof of Social Security Coverage

Each posted worker must carry their A1 certificate (formerly E101 form), issued by the social security body of their home country. This document certifies that the employee remains affiliated with their home country’s social security regime and that contributions are duly paid.

This is the most critical document during an inspection. Its absence creates a presumption of fraud: the URSSAF can retroactively demand the payment of French social security contributions for each worker lacking an A1, representing substantial costs.

The “Hard Core” of French Labor Law: What you must respect

Although your employees keep their foreign contract, French law (Art. L.1262-4 of the Labor Code) mandates that during their posting, they benefit from a minimum foundation of French rights:

The BTP Card (Carte BTP): Mandatory for every site worker

Since 2017, any employee in the construction sector working in France-including posted workers-must possess and wear a BTP Professional Identification Card.

How to get it?

• The application is made online at cartebtp.fr by the employer or their representative in France.
• The card is personal, bearing the worker’s photo, name, qualifications, and employer’s name.
• The processing time is approximately 2 to 4 weeks after the request. Plan this well in advance of the site start date.

6. Who is the employer’s representative in France and why are they mandatory?

This is often the last obligation foreign companies think of, yet it is one of the most critical-and the most heavily penalized.

The legal obligation (Art. L.1262-2-1 of the Labor Code)

Any company established outside of France posting at least one employee on French territory must designate an employer’s representative in France for the entire duration of the posting.

What is their exact role?

The representative is the exclusive point of contact between your company and the French control authorities (Labor Inspectorate, URSSAF, Customs, Police).

In practice, during a site inspection, the labor inspector will ask to contact your representative. They must be reachable and able to respond within a reasonable timeframe (typically 8 hours). They must be able to present or immediately transmit:

• The SIPSI declaration receipt.
• Employment contracts (translated into French).
• Payslips.
• Timesheets (with start/end times and breaks).
• A1 certificates for each worker.
• Proof of actual payment of salaries.

7. Summary: Penalties for non-compliance

To fully grasp the importance of each obligation, here is a summary table of the fines and risks involved:

Furthermore, the Labor Inspectorate can order the immediate suspension of the service provision in case of serious breaches, meaning a site shutdown and significant financial losses for your company.

FAQ – Your Frequently Asked Questions

Do I absolutely need to create a French subsidiary (SASU/SARL) to get decennial insurance?

No. Creating a branch office of your foreign company is sufficient to obtain the SIRET and the Kbis required by insurers. A branch is legally simpler and less costly to set up than an independent subsidiary.

How long does it take to get a SIRET in France?

The branch registration timeframe varies depending on the completeness of your file and the registry’s workload. Expect between 2 and 6 weeks from the complete submission of the file to the INPI or Commercial Court.

Is my home country’s decennial insurance accepted in France?

In theory, European freedom to provide services allows it if the coverage is equivalent. In practice, almost all French project owners and architects require an insurance certificate underwritten in France. We recommend taking out a decennial policy with a licensed French insurer.

As a subcontractor, do I need decennial insurance?

The decennial liability (Spinetta Law) weighs on the builder directly linked to the project owner. As a subcontractor, you are not legally obligated to take out decennial insurance. However, the main contractor will very often demand it in the subcontracting agreement.

How long can a posting in France last?

The initial posting is limited to 12 months. It can be extended by an additional 6 months upon motivated notification to the Labor Inspectorate.

Conclusion: Surround yourself with the right partners to build in France

Working on construction sites in France as a foreign company offers considerable growth opportunities. The regulatory framework is demanding, but far from insurmountable if you are well supported.

With the right partners, these steps turn into simple administrative formalities-and you can focus on what you do best: building.