Northern Ireland VAT number check
Check a Northern Ireland supplier's or customer's number against VIES, the European Commission's register. Below: the format, what it's called locally, and the mistakes that make a correct number fail.
Paste the number with or without the country prefix. Nothing you enter is stored.
The format
| Prefix | XI |
|---|---|
| After the prefix | 9 digits (or 12 for branches) |
| Structure | 3, 4 and 2 digits (9 in all); or those followed by 3 more for branch traders; or GD or HA plus 3 digits for government departments and health authorities. |
| Example | XI123456789 |
You can paste the number with spaces, dots or dashes; the checker removes them.
What it's called
UK VAT registration number, shown with the XI prefix instead of GB.
XI isn't a separate number. A business trading goods between Northern Ireland and the EU under the Windsor Framework uses its UK VAT number with XI in place of GB.
Registered, but invalid in VIES?
The business has to tell HMRC that it trades goods under the Windsor Framework. Only then does the XI number validate in VIES.
What trips people up
- XI is for goods only. Northern Ireland follows EU VAT rules for goods, not services.
- GB numbers can't be checked in VIES. Use HMRC's service for GB.
- Invoices for goods from Northern Ireland to EU VAT-registered customers must show the XI prefix.
Other ways to check
HMRC, check a UK VAT number: Checks the underlying UK number (GB). Use VIES for XI. For cross-border trade, the VIES result above is the one to keep with your VAT records.
Sources
Formats from the European Commission's VIES FAQ, checked 16 October 2026. Rules can change; the tax authority's own guidance wins.
Questions about Northern Ireland VAT numbers
What is the format of a Northern Ireland VAT number?
XI followed by 9 digits (or 12 for branches). 3, 4 and 2 digits (9 in all); or those followed by 3 more for branch traders; or GD or HA plus 3 digits for government departments and health authorities. Example: XI123456789.
What is a Northern Ireland VAT number called?
UK VAT registration number, shown with the XI prefix instead of GB. XI isn't a separate number. A business trading goods between Northern Ireland and the EU under the Windsor Framework uses its UK VAT number with XI in place of GB.
Why would a correct Northern Ireland VAT number show as invalid in VIES?
The business has to tell HMRC that it trades goods under the Windsor Framework. Only then does the XI number validate in VIES.