How to check a UK VAT number is valid

You check a UK VAT number with HMRC’s free Check a UK VAT number service on GOV.UK. Enter the 9-digit number and it tells you whether the number is valid and which business name and address it is registered to. If you also enter your own VAT number, HMRC gives you a reference number as proof of when you checked.

Why check a supplier’s VAT number?

Checking protects your VAT reclaim. HMRC’s VAT Notice 700 says you need valid evidence, normally a VAT invoice, to reclaim input tax, and that you generally cannot reclaim VAT that was charged incorrectly. A business that is not registered should not charge VAT at all.

HMRC’s own fraud manual lists false invoices as a sign of VAT fraud, including invoices built from genuine letterheads or details taken from other traders (VATF23300). A quick check catches a made-up number, or a real number that belongs to a different business.

Check when:

• you take on a new supplier who charges VAT
• a supplier’s bank details or address change
• an invoice looks unusual, such as a large one-off charge
• a customer gives you a VAT number for a business-to-business sale

How to check a UK VAT number: step by step

The GOV.UK checker takes about a minute.

1. Find the number. Look on the supplier’s VAT invoice, receipt or website. Notice 700 (paragraph 16.3.1) requires every full VAT invoice to show the supplier’s VAT registration number.
2. Open the service at gov.uk/check-uk-vat-number.
3. Enter the 9 digits. You cannot search by business name.
4. Add your own VAT number if you want proof. HMRC then returns a reference number for the check. Non-UK businesses can leave this blank.
5. Compare the result. The name and address shown should match the invoice.
6. Save the result. Keep a screenshot or the reference number with the supplier’s records.

What the result tells you

The result is either a match or no match.

A business still waiting for HMRC to confirm its registration cannot be checked yet.

What a UK VAT number looks like

A standard UK VAT number is 9 digits. It is usually written with a country prefix: GB 123456789 for most businesses. Some third-party guides describe longer formats for VAT groups and government bodies; HMRC’s public checker is built around the 9-digit number, so enter those 9 digits.

Northern Ireland businesses that trade goods with the EU use an XI prefix instead. GOV.UK’s guidance on moving goods between Northern Ireland and the EU says they must use the XI number on all documents sent to EU customers or suppliers. The underlying 9 digits are the same as the GB number.

For other tax references, see our guide to UK tax identification numbers. If you want a document showing your own registration, see how to get a VAT certificate.

Which checker applies to you?

Use the checker that matches the prefix.

• If the number starts GB, use HMRC’s GOV.UK checker.
• If the number starts XI, it relates to Northern Ireland goods trade with the EU. The XI prefix sits in front of the business’s existing UK number, so check those 9 digits on GOV.UK.
• If the number has an EU country prefix (such as FR, DE or IE), use the European Commission’s VIES service, which GOV.UK links to from the checker page.
• If you check numbers in bulk, use software built on HMRC’s API (see below).

Checking VAT numbers in software

HMRC’s Check a UK VAT Number API lets accounting and invoicing software run the same check. Version 1 was removed on 17 February 2025. Version 2.0 offers a simple check, and a verified check that returns a reference number. Developers need production credentials from the HMRC Developer Hub, which HMRC says takes about two weeks.

What to do if a VAT number is not valid

Ask the supplier first, since many failures are typing errors. Ask for a corrected invoice; Notice 700 (paragraph 19.5.3) says that where you lack a valid invoice you should first request one from the supplier.

If the supplier cannot explain it, hold back the VAT element until they can. If you suspect fraud, report it to HMRC through the online form or on the fraud hotline, 0800 788 887 (Monday to Friday, 9am to 5pm). HMRC asks you not to investigate further or warn the business. For general VAT questions, the VAT helpline is 0300 200 3700; see our HMRC VAT helpline guide.

What to do now

• Add a VAT number check to your new-supplier checklist.
• Store the HMRC reference number with each supplier record.
• Re-check numbers when bank details change.
• Read our VAT hub for the rules on reclaiming VAT.

Frequently asked questions

Is the HMRC VAT number checker free?

Yes. The Check a UK VAT number service on GOV.UK is free and needs no login.

Can I look up a company’s VAT number by name?

No. GOV.UK says you cannot search by business name. Find the number on the business’s invoices, receipts or website, then check it.

How do I prove I checked a VAT number?

Enter your own VAT number when you run the check. HMRC then gives you a reference number, which you can keep with your records as evidence.

How many digits is a UK VAT number?

A standard UK VAT number has 9 digits, usually shown with a GB prefix. Northern Ireland businesses trading goods with the EU show the same digits with an XI prefix.

What if a supplier’s VAT number does not match its name?

Ask the supplier for an explanation and a corrected invoice before you reclaim the VAT. If you suspect fraud, report it to HMRC on 0800 788 887 or online.