UK VAT numbers

A UK VAT number identifies a business registered for VAT with HM Revenue & Customs (HMRC). On B2B invoices and contracts you will see a GB prefix — for example GB116300129. Before you pay a UK supplier or approve a VAT reclaim, an HMRC VAT check confirms the registration is genuine and active.

UK VAT number format

Most GB VAT numbers use GB followed by nine digits; some VAT groups use 12 digits. The number should appear on official invoices and HMRC letters. If a supplier quotes a UK tax ID without the GB prefix, or the length looks wrong, run a UK VAT validation lookup before you rely on it.

HMRC and UK VAT verification

Since Brexit, UK numbers are checked through HMRC's registry, not EU VIES. HMRC VAT verification returns valid or invalid status plus the registered business name and address on file — what you need to match a supplier to their invoice. Our tool queries this source when you enter a GB number.

When to check a UK VAT number

Run a UK VAT lookup when onboarding a new supplier, reviewing a high-value invoice, or confirming a customer before a B2B supply. Finance teams and accountants treat a check UK VAT number step as standard practice before approving payment — it takes seconds and leaves a clear record that you checked official HMRC data. See why verifying VAT numbers matters and our validation guide.

Check a UK VAT number free

Use our free UK VAT checker for instant HMRC results — no account needed. For EU member states via VIES, read EU VAT numbers explained. Country how-to tips are in our FAQ.