The format: 14 digits, no letters
The SIRET identifies an establishment, that is, a place of activity: head office, branch, shop, warehouse. It is made of the 9 digits of the company's SIREN, followed by 5 digits, the NIC (numéro interne de classement). For example, 552 100 554 00039 is the SIRET of an establishment of the company whose SIREN is 552 100 554. The difference between the two numbers is detailed in SIREN vs SIRET vs NIC: what is the difference?.
A SIRET contains only digits. The spaces, dots and hyphens found on documents (552 100 554 00039) are not part of the number and must be removed before any check. A number of 13 or 15 characters is wrong from the start, as is a number containing the letter O instead of a zero, a very frequent mistake when copying a number by hand or from a PDF.
The Service-Public page “How to obtain a Siren or Siret number?” (in French) recalls who receives these numbers and when.
Spotting a typing mistake
The SIRET carries a check digit: if a digit is missing, added or swapped, the number is recognised as invalid. It is a useful first filter right in the sign-up form of a customer or supplier, to ask them to correct their entry at once.
But a correct check digit proves nothing else: it guarantees neither that the establishment exists, nor that it is still open, nor that it belongs to your customer. That is the purpose of the next checks.
A valid SIRET is not necessarily active
Three different questions hide behind “is this SIRET good?”:
| Question | What it checks | If the answer is no |
|---|---|---|
| Is the number well formed? | 14 digits and a correct check digit | Probable typing mistake: ask for the number again |
| Does the establishment exist? | The number is on record | Invented or wrong number, even if well formed |
| Is the establishment active? | It is not closed | Closed establishment: the customer may have moved |
A closed establishment keeps its SIRET for ever: the number is never reissued. But that does not mean the company has disappeared. A company that closes a branch or moves its head office keeps existing, with the same SIREN, under another SIRET. Conversely, when the company closes, all its establishments close with it. Knowing which case you are in means looking at both the establishment and the company, as shown in Struck-off, closed or dormant French company: how to tell.
The SIRET also helps check the address: that of an establishment matches a precise address. If the invoice shows an address different from the establishment's, that deserves a question before paying.
The most common mistakes
- Confusing SIREN and SIRET: a 9-digit number is a SIREN; only a 14-digit number is a SIRET (What is a SIREN number and how to find it);
- The SIRET of a former head office: the company moved, the old establishment is closed, but the invoice or contract still carries its number;
- The SIRET of another company in the group, for example the parent company or the subsidiary that handles accounting;
- A lost digit: a spreadsheet that removes leading zeros or shows the number in scientific notation;
- A foreign SIRET: the SIRET exists only in France; Belgium and Switzerland have their own numbers (see Belgian enterprise number and Swiss UID number).
The last case is misleading in files of European customers: a 10-digit number is not an incomplete SIRET, it is probably a Belgian enterprise number.
With Companies: the SIRET checked in one call
The GET /v2/validate route accepts the SIRET with or without spaces, dots and hyphens, and returns each check separately:
curl "https://companies.jsonpage.com/v2/validate?siret=55210055400039" \
-H "X-API-Key: $COMPANIES_API_KEY"The response lists the format of the number (siret_format), the check digit (siret_key), the existence of the establishment (siret_exists) and its status (siret_active), then the company's basic record with its address. It is returned even when the establishment is closed, which lets you show a precise message instead of a plain refusal. A check that depends on a failed check is omitted: a badly formed SIRET is not looked up.
You can also pass the SIREN (id=FR-552100554) or the VAT number at the same time to check that they designate the same company. For a whole file, enrichment in the account area completes each row. The SIRET applies to France only.
Frequently asked questions
How many digits does a SIRET number have?+
Fourteen: the 9 digits of the SIREN followed by the 5 digits of the NIC. The spaces are not part of the number.
Does a valid SIRET always designate an active company?+
No. A well-formed SIRET can designate a closed or non-existent establishment. You need to check its existence and its status.
What should I do if a customer's SIRET belongs to a closed establishment?+
Ask for the SIRET of their current establishment. The company may still exist under the same SIREN, with another address.
Can a SIRET be foreign?+
No. The SIRET exists only in France. Belgian and Swiss companies have an enterprise number or a UID.
Keep reading
- SIRENWhat is a SIREN number and how to find itThe 9-digit format, who gets one, where it appears and how to find a company's SIREN from its name.
- SIREN · SIRETSIREN vs SIRET vs NIC: what is the difference?The company and its establishments: 9 or 14 digits, the role of the NIC and the right number for each use.
- VERIFICATIONIs this company real? Checks before signingA six-point checklist: identifier, status, name and address, VAT, signals and sanctions lists.