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Northern Ireland VAT number format

A Northern Ireland VAT identification number is the prefix XI followed by 9 or 12 digits, or GD/HA + 3 digits; XI110305878 is a well-formed example. The national check digit is public, so a mistyped number is caught before VIES is asked. Structure as published in the Commission’s VIES FAQ, consulted 2026-10-24.

Structure

Prefix XI, then 9 or 12 digits, or GD/HA + 3 digits. The regular expression the API applies to the part after the prefix is ^(?:[0-9]{9}|[0-9]{12}|(?:GD|HA)[0-9]{3})$; letters are upper-cased and spaces, dots and dashes removed before the test.

Country prefixStructureExamplePublic check digit
XI9 or 12 digits, or GD/HA + 3 digitsXI110305878yes, verified before VIES

The check digit

Northern Ireland publishes the algorithm of its check digit, so an impossible number is refused before VIES is asked: the answer says structure.checksum: "failed", costs nothing and reaches no upstream. The same algorithms are implemented by the open libraries (jsvat, python-stdnum).

How to validate it

The structure says whether a string can be a Northern Ireland VAT number; only VIES says whether it is registered. The free check below asks VIES live and shows the registered name and address where Northern Ireland publishes them; the API does the same from your code.

curl — validate XI110305878 on VIES
curl "https://veriport.io/api/v1/vat/validate?number=XI110305878"

What a valid answer proves

That the number was registered for intra-EU trade at the moment of the check. Keep the date and, on paid tiers, the VIES consultation number: together they are the evidence a tax audit asks for when an intra-EU supply was zero-rated.

Questions

How many digits does a Northern Ireland VAT number have?
9 or 12 digits, or GD/HA + 3 digits, after the two-letter prefix XI: XI110305878 is an example.
Is XI110305878 a real VAT number?
It is a well-formed example used in the documentation; whether it is registered today is VIES’s answer, not this page’s. Check it with the free tool.
Why is Northern Ireland in VIES?
Under the Windsor Framework, Northern Ireland follows EU VAT rules for goods; XI numbers are in VIES for goods only. The rest of the UK is not in VIES; its numbers are checked through HMRC (on the roadmap).

Free: VIES asked live, the answer dated and sourced.

Check a VAT number

Sources