Checks
What a UK VAT number looks like
| Type | Format | Example |
|---|---|---|
| Standard | GB + 9 digits | GB 123 4567 89 |
| Branch or group member | GB + 12 digits (9 digits + 3-digit branch code) | GB 123 4567 89 001 |
| Government department | GBGD + 3 digits (000–499) | GBGD001 |
| Health authority | GBHA + 3 digits (500–999) | GBHA599 |
| Northern Ireland (goods with the EU) | XI + the same 9 digits | XI 123 4567 89 |
How the check digits work
The last two digits of a 9-digit VAT number are check digits. Multiply the first seven digits by 8, 7, 6, 5, 4, 3 and 2, add them up, and add the last two digits as a number. For a valid number the total divides exactly by 97. Numbers issued from around 2010 use a second version of the test, where the total plus 55 divides exactly by 97. This catches most typing mistakes, such as a wrong or swapped digit.
When to check a VAT number
- Before reclaiming VAT on a supplier’s invoice: you can only reclaim VAT on a valid VAT invoice from a registered business.
- If an invoice shows VAT but looks wrong, for example no VAT number, or a business you think is too small to be registered. See charging VAT when not VAT registered.
- Before zero-rating or reverse-charging a sale to a business customer, to show they’re in business.
FAQ
How do I check if a UK VAT number is valid?
Use HMRC’s free Check a UK VAT number service on GOV.UK. It shows whether the number is registered and the business name and address. This page checks the format and check digits first, to catch typing mistakes.
How many digits is a UK VAT number?
Nine digits after the GB prefix, for example GB 123 4567 89. Some branches and group members have 12 digits, and government departments and health authorities use GBGD or GBHA followed by 3 digits.
What does an XI VAT number mean?
XI numbers are used by VAT-registered businesses in Northern Ireland that trade goods with the EU. The 9 digits are the same as the business’s GB number.
What should I do if a supplier’s VAT number isn’t valid?
Don’t reclaim the VAT yet. Ask the supplier to confirm their VAT number, check it with HMRC’s service, and ask for a corrected invoice if needed.