§ FORMAT · 4 MIN READ
UK VAT number format explained
Standard, branch, government, and health authority formats.
Published 2026-04-16 · Countersure
The standard 9-digit format
Most UK VAT-registered businesses receive a 9-digit number. The check digit is computed by HMRC and not exposed in any public algorithm.
The format is presented as GB followed by the digits, e.g. GB123456789.
Branch numbers (12 digits)
Group registrations and large corporates with multiple branches use a 12-digit format — 9 digits plus a 3-digit branch identifier.
Example: GB123456789001.
Government and health authority prefixes
GD prefix identifies government departments — e.g. GBGD001.
HA prefix identifies NHS health authorities — e.g. GBHA999.