A National Insurance number (NINO) is the personal reference HMRC and DWP use to track your National Insurance contributions, tax and benefits. Payroll and HR teams need to confirm a new employee’s NINO is well-formed before adding it to a payroll system. This free validator checks a NINO against the official structural rules without sending it anywhere.
How it works
A NINO has the canonical pattern AB123456C and must satisfy several rules:
- Length: nine characters, ignoring spaces.
- First prefix letter: any letter except D, F, I, Q, U, V — and never O.
- Second prefix letter: any letter except D, F, I, O, Q, U, V.
- Reserved prefixes: the two-letter prefix must not be BG, GB, KN, NK, NT, TN or ZZ.
- Digits: exactly six digits in the middle.
- Suffix: a single letter that must be A, B, C or D.
The validator evaluates each rule independently and reports the first thing that is wrong, so a mistyped letter is quick to spot.
Example
QQ 12 34 56 C → prefix QQ (both letters allowed, not reserved), digits 123456, suffix C. All rules pass, so the format is valid.
By contrast DA123456C fails because the first letter D is disallowed, and ZZ123456A fails because ZZ is a reserved prefix.
Notes
A valid format does not prove the NINO has been issued to a real person — only HMRC and DWP can confirm that. Prefixes such as TN and NT are reserved for temporary or system use. All checks run locally in your browser.