Short answer. A company number identifies a registered company at Companies House and is public. A VAT registration number identifies a business registered for VAT with HMRC. A UTR is a private tax reference issued by HMRC and should not be published.
Company registration number
Issued by Companies House when a company or LLP is incorporated. Eight characters, sometimes with a letter prefix. It is public, appears on the register, and never changes for the life of the company, even if the company changes its name.
VAT registration number
Issued by HMRC when a business registers for VAT. UK numbers are usually shown as GB followed by nine digits. Many companies are never VAT registered, so the absence of a VAT number is not a warning sign on its own. You can confirm a UK VAT number using the HMRC checking service.
Unique Taxpayer Reference (UTR)
A ten-digit reference issued by HMRC for tax purposes. Corporation Tax UTRs relate to companies; self assessment UTRs relate to individuals. A UTR is confidential. It is not on the public register and should not be printed on invoices or a website.
Quick comparison
- Who issues it: Companies House (company number); HMRC (VAT number and UTR).
- Public or private: company number is public; VAT number is verifiable; UTR is private.
- What it proves: registration only. None of them tells you whether a business is solvent or trustworthy.
Which one is being asked for
Suppliers onboarding you usually want the company number and, if applicable, the VAT number. Accountants and HMRC correspondence use the UTR. If a request is unclear, ask which register the number should appear on: that distinguishes them immediately.
This guide is general information about public company records, not legal, tax or financial advice. Independent service. Not affiliated with Companies House or GOV.UK.