United Kingdom
What is a National Insurance Number?
A UK National Insurance number links an individual's National Insurance contributions and tax record. It is personal administrative data, not proof of identity by itself, and test systems should use clearly fictional fixtures that never reach HMRC or employment reporting.
Common format
AA 12 34 56 A
A format description is not a real-world validation result.
Key facts
- โThe common display has two prefix letters, six digits, and a final suffix letter.
- โNot every two-letter prefix is allocated; format-only generators do not prove issuance.
- โSpacing may vary in input, so normalize separately while preserving the original display value.
- โUse HMRC-approved test guidance for integrations that communicate with real government services.
Testing and privacy boundary
FakeAddrGen only creates formatted fictional fixtures. Never submit output to government, tax, identity, credit, employment, benefit, or financial systems, and never copy real identifiers into screenshots, logs, tickets, or staging databases. Use institution-approved sandboxes for official integrations.