United Kingdom VAT registration number: the GB prefix then nine digits, written either solid or in three groups. The prefix survived the country's departure from the European VAT system, so this is deliberately separate from the eu-vat pattern.
Label: UK_VAT
(?<!\w)GB\s?\d{3}\s?\d{4}\s?\d{2}(?!\w)Our VAT number is GB 123 4567 89 on invoices. → GB 123 4567 89Registered as GB123456789 with HMRC. → GB123456789The code GB12345678 is too shortReference 123456789Tags: uk, government-id, business, finance