The SIREN and the SIRET are the identifiers assigned by INSEE (the French national statistics institute) to businesses and their establishments, in the SIRENE directory. The SIREN is a 9-digit number that identifies the legal entity — the business — throughout its existence.
The SIRET, for its part, has 14 digits: it consists of the SIREN followed by a 5-digit NIC (internal classification number) that identifies a specific establishment. A business therefore has a single SIREN, but as many SIRETs as it has establishments (head office, warehouse, store, etc.). An establishment's SIRET changes if it relocates. Alongside these identifiers come the APE/NAF code (line of business) and the intra-EU VAT number, built from the SIREN.
These numbers are public: the SIRENE directory is published as open data, which makes it possible to verify the existence and status (active or ceased) of a business or an establishment. The SIREN remains stable even when the head-office address changes, whereas the SIRET is tied to a given physical location.
In a management system, the SIREN and the SIRET serve to reliably identify customers and suppliers, avoid duplicates and secure legal data. They are among the mandatory details on invoices and determine how electronic invoices are routed via the PDP directory. In eyeot's CRM, these identifiers qualify company records for unambiguous commercial and administrative exchanges.