UK VAT number checker

Check that a UK VAT number is in a valid format and that its check digits add up, which catches most typing mistakes and invented numbers. Then confirm who it's registered to with HMRC.

UK VAT number formats

Format	Who uses it
`GB 999 9999 99`	Most VAT-registered businesses (9 digits)
`GB 999 9999 99 999`	Branch traders: the 9-digit number plus a 3-digit branch
`GBGD999`	Government departments
`GBHA999`	Health authorities
`XI 999 9999 99`	Northern Ireland businesses moving goods to or from the EU

Formats from the European Commission's table^source and HMRC's guidance on the XI prefix^source. Standard numbers have 9 digits.

How the check digits work

The last two digits of a 9-digit VAT number are calculated from the first seven using a standard formula^source, a "modulus 97" check.^source We use the same formula as HMRC's own software^source:

Multiply the first seven digits by 8, 7, 6, 5, 4, 3 and 2, and add them up.
Add the last two digits, read as one number.
The number is valid if the total divides exactly by 97, or does once 55 is added.

Passing this check only means the number is in the right format.^source It doesn't prove the number is registered or belongs to the business in front of you.

Confirm a VAT number with HMRC

HMRC's free Check a UK VAT number service shows the name and address of the business a number is registered to.^source Compare them with the invoice before you pay or reclaim VAT. For EU numbers, use the European Commission's VIES service^source, which has not checked GB numbers since 1 January 2021.

Frequently asked questions

What does a UK VAT number look like?

Usually 9 digits, often written with "GB" in front and spaced as GB 123 4567 89. Branch traders have 12 digits, and government departments and health authorities have short codes such as GBGD001.

Does a valid format mean the business is VAT registered?

No. It only means the number could exist. To see whether it's registered, and to whom, use HMRC's Check a UK VAT number service.

When should I check a VAT number?

When a new supplier sends a VAT invoice, especially before you pay a large amount or reclaim the VAT. A number that fails the check digits is a warning sign of a typing error or a false invoice.

What is an XI VAT number?

Businesses in Northern Ireland that move goods to or from the EU use XI instead of GB in front of their normal VAT number.

Can I check an EU VAT number here?

No. EU VAT numbers are checked with the European Commission's VIES service. VIES stopped checking GB numbers on 1 January 2021.

Sources

Facts last checked 31 October 2026. See all sources.