Company number
A company number is the unique, permanent identifier Companies House assigns to a company when it is incorporated.
By the Company Shark team · Reviewed · Sourced from the official Companies House register
The company registration number (CRN) is the definitive way to identify a UK company. Unlike a company name — which can change, and which several companies may closely resemble — the number is unique and never changes for the life of the company, even if the business is renamed, restructured or sold.
The format tells you something about the company. Eight digits (e.g. 12345678) is the standard for companies registered in England and Wales. A two-letter prefix indicates a different registrar or company type: SC for Scotland, NI for Northern Ireland, OC for an LLP in England and Wales, SO for a Scottish LLP, and FC for an overseas company, among others.
Because it is unique and stable, the company number is the safest reference to use in contracts, invoices, due-diligence records and CRM systems. Matching on company name alone risks confusing two different businesses with similar names, or losing track of one that has since rebranded.
Example
Searching the number 00000006 returns the same company no matter what it is currently called; searching “Marine” returns thousands of unrelated businesses. Professionals quote the number precisely for this reason.
On Company Shark
Company Shark uses the company number as the canonical key for every profile — the URL of each page is /company/{number} — so a link always resolves to exactly one company, and exports include the number on every row for clean CRM matching.
Related
See it on real companies
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