The SIREN consists of 9 digits: 8 sequentially assigned digits plus a 9th check digit (calculated using the Luhn formula). It is assigned once, when the company is created, and remains the same throughout its lifetime—even in cases of relocation, change of management or statutory amendments.
It identifies the legal entity: an SAS, SARL, association, sole trader or administration. It is not an establishment number: a company with a head office and three branches has one SIREN but four SIRETs.
Do not confuse:
The SIREN is public and free data. It can be found:
From a single SIREN, you can trace the company name, legal form, incorporation date, head office address, APE/NAF code, workforce range and declared directors. This makes it the most useful enrichment key for a prospect or customer database.
In B2B, manually entering a company name leads to duplicates and errors: “Dupont & Fils”, “Dupont et fils SARL”, “DUPONT”. The SIREN, however, is unique: one number per entity. It is therefore the ideal deduplication key.
Linking a record to its SIREN allows auto-filling essential details (exact legal name, registered address, legal form, workforce size) instead of retyping them, and detecting changes (striking off, change of director). A CRM that queries the Sirene API turns a simple number into a complete, up-to-date record.
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Essai gratuit 14 jours What the Orizen CRM module costsThe SIREN (9 digits) identifies the company as a legal entity. The SIRET (14 digits) identifies a specific establishment of that company: it consists of the SIREN followed by a 5-digit NIC code unique to the establishment. A company therefore has one SIREN but as many SIRETs as it has establishments (head office + branches).
No. The SIREN is assigned once at creation and remains the same throughout the company’s lifetime, even in case of relocation, change of director, name or legal form. It is only removed upon the company’s final striking off and is never reassigned to another entity.
Using the SIREN, the free INSEE Sirene API returns the legal name, registered address, APE/NAF code, legal form, workforce size range and creation date. A CRM connected to this source can auto-fill the customer record and keep it up to date. The Orizen CRM uses this principle to ensure record accuracy and prevent duplicates from the moment of entry.