When you create a business in France, the administration assigns you a series of numbers composed solely of digits. Among them, the SIREN and the SIRET appear on every official document, every invoice, every contract. These two identifiers are related, but they do not refer to the same thing.
The Sirene directory is the database that hosts both of them. Understanding their relationship helps avoid concrete mistakes during a move, the opening of a second location, or a tax declaration.
The NIC, the unknown link between SIREN and SIRET
Most guides explain the SIREN (9 digits, identifies the company) and the SIRET (14 digits, identifies the establishment). Few detail the mechanism that connects the two: the NIC, or Internal Classification Number.
The NIC is a sequence of 5 digits assigned by INSEE to each establishment of the same company. Your SIRET is constructed as follows: the 9 digits of the SIREN, followed by the 5 digits of the NIC. If your SIREN is 123 456 789 and the NIC of your head office is 00012, your SIRET will be 123 456 789 00012.
Why does this detail matter? Because the NIC changes with each new establishment or move. Your SIREN remains the same throughout the life of the company, but the NIC (and therefore the SIRET) evolves as soon as the address of an establishment is changed. A company with three stores has a single SIREN and three distinct SIRETs, each with a different NIC.
As specified by the Gestion Entreprise info website, this distinction has direct consequences on the administrative procedures and reporting obligations of each establishment.
Sirene Directory: what INSEE really stores about your business
The Sirene directory is not just a simple directory. It is the national database managed by INSEE that lists all businesses, associations, and public organizations registered on French territory.
For each entity, the directory contains much more than the SIREN and SIRET. You will find the company name, the address of each establishment, the legal category, the date of creation, and the famous APE code (Main Activity Exercised).
The Sirene situation notice, a document without legal value
You can download a situation notice for free from the INSEE website. This document summarizes the information recorded the day before your consultation. Note: the situation notice has no official legal value. It simply certifies what the database contains at a given moment. To prove the legal existence of your company, it is the Kbis extract (or K for individual businesses) that is valid.
Opening of Sirene data via public APIs
For several years, the data from the Sirene directory has been accessible as open data. The Business Directory, supported by the Interministerial Digital Directorate, offers a public API that allows real-time querying of the database. Private platforms also exploit this data to provide verification, commercial prospecting, or supplier compliance services.
For businesses, this opening means that your Sirene information is accessible by anyone: clients, partners, competitors, administrations. Keeping your address, activity, and status updated in the directory is not optional.
SIREN and SIRET on your documents: what to put where
You are drafting an invoice, a quote, or having a stamp printed. Which number should you indicate? The answer depends on the document and its function.
- On an invoice or quote, you must mention the SIRET number of the issuing establishment, not just the SIREN. The SIRET identifies the precise location from which the service or sale originates, which is required by the Commercial Code.
- On the legal mentions of a website, the SIRET of the head office is expected, accompanied by the RCS number if you are registered with the trade register.
- On a company stamp, the common practice is to include the complete SIRET, as it inherently includes the SIREN (the first 9 digits).
The SIREN alone is sufficient for certain internal procedures or to identify your business in a search. However, as soon as a document engages a commercial or tax relationship, the SIRET is required.
Change of APE code and NAF nomenclature: what evolves in Sirene
An often-overlooked aspect concerns the APE code associated with your Sirene record. This code, derived from the French activity nomenclature (NAF), classifies your main activity within a statistical grid.
Since 2025, the NAF is undergoing a thorough revision. Some APE codes are automatically reclassified by INSEE, even if the company has not changed its activity. The digital sectors, platforms, and hybrid activities are particularly affected.
This reclassification has no impact on your SIREN or your SIRET. However, it may alter your eligibility for certain public aids or sectoral schemes, which often filter beneficiaries by APE code. If your code changes without your knowledge, you risk losing access to a scheme or, conversely, not knowing that you are now eligible.
To check your future APE code in the new nomenclature, the sirene.gouv.fr portal offers a dedicated tool.
Three reflexes to keep to avoid common mistakes
- After a move, check that your new SIRET appears in the Sirene directory. The update time can take several days after the declaration at the single window.
- Do not confuse SIRET and Urssaf number: these are two distinct identifiers, managed by different organizations. The Urssaf number is used for social contributions, while the SIRET is for administrative identification.
- If you open a second establishment, anticipate that each site will have its own SIRET. The reporting obligations (VAT, CFE) may vary from one establishment to another depending on the municipality of establishment.
The SIREN identifies your legal structure, the SIRET locates each of its establishments, and the Sirene directory centralizes everything. Keeping these three levels in mind helps avoid confusion during each formal procedure, from the first day of activity to a potential cessation.