Do Companies House numbers have a check digit?

No. Unlike VAT or IBAN numbers, a UK Companies House registration number (CRN) has no check digit. Validation is purely about matching the correct prefix and length, so this tool verifies format and jurisdiction rather than computing a checksum.

What do the letter prefixes mean?

The two-letter prefix encodes jurisdiction and entity type. SC is a Scottish company, NI is Northern Ireland, OC/SO/NC are LLPs in England-and-Wales, Scotland and NI respectively, and FC/SF/NF are overseas companies with a UK branch. A plain 8-digit number is an England-and-Wales company.

How many characters is a CRN?

Always 8 characters. It is either 8 digits, or a 2-letter prefix followed by 6 digits. Leading zeros are significant, so 00012345 is different from 12345 and must be entered in full.

Does a valid format mean the company exists?

No. A valid format only confirms the number could be a real CRN. It does not confirm the company is registered, active, or not dissolved. Use the official Companies House register to check the company's live status.

Is my data sent anywhere?

No. The format check runs entirely in your browser. The number you enter never leaves your device and no Companies House API call is made.

UK Companies House Number Validator

A UK Companies House number — also called a company registration number (CRN) — is the unique 8-character identifier issued to every company, LLP and registered society in the United Kingdom. Because the prefix encodes both the jurisdiction (England & Wales, Scotland or Northern Ireland) and the entity type (limited company, LLP, overseas branch, society and more), getting the format right matters in KYC, supplier-onboarding and invoicing systems. This free validator checks the format against every recognised pattern and names the jurisdiction.

How it works

Companies House numbers do not carry a check digit, so validation is a pattern test, not a checksum:

Uppercase the input and strip spaces and punctuation, leaving 8 characters.
If all 8 characters are digits, it is an England & Wales company (leading zeros included).
Otherwise the first two characters must be a recognised jurisdiction prefix, and the remaining six characters must all be digits.

The recognised prefixes include SC (Scotland), NI (Northern Ireland), OC/SO/NC (LLPs), FC/SF/NF (overseas companies with a UK branch), IP/SP (industrial & provident societies), RC/SR (Royal Charter), IC (investment companies) and several historic forms such as R0.

Example and notes

SC123456 matches the SC prefix plus 6 digits, so it is reported as a valid Scotland limited-company format. A plain 12345678 is reported as an England & Wales company. An input like XY123456 fails because XY is not a recognised prefix.

Because there is no checksum, a valid format cannot confirm the company actually exists, is active, or has not been dissolved — only the live Companies House register can tell you that. Everything here runs locally, so no number is sent to any server.