National Insurance Number Checker
Enter National Insurance numbers, one per line. This checks the format and the prefix rules only. It cannot show that a number has been issued.
Dieser Inhalt ist auf Englisch.
Durchgerechnete Beispiele
Typed without spaces
ab123456d
AB 12 34 56 D: format accepted
The number is set out in pairs and capitalised.
A prefix that is not allocated
BG123456A
BG123456A: the prefix BG is not used for National Insurance numbers
BG is one of the prefixes that is not used.
Über National Insurance Number Checker
This checker tests whether National Insurance numbers are written in the right format. Paste one per line, with or without spaces, and each is tested against the layout and prefix rules.
It is a format check only. It cannot look a number up or say whether one has been issued to anyone. A number that passes is shown in pairs, the way it appears on official letters.
So verwenden Sie National Insurance Number Checker
- Enter or paste the numbers, one per line.
- Read the result for each line.
- Check your own number against your payslip, P60 or a letter from HMRC if anything is marked.
Typische Einsatzzwecke
- Catching typing mistakes in payroll or HR spreadsheets
- Tidying numbers into the standard layout
- Checking a number copied from a form
- Explaining why a number is rejected by an online form
Quellen
Zuletzt geprüft am 15. Oktober 2026.
Häufige Fragen
What is the format of a National Insurance number?
Two letters, six digits and a final letter from A to D, for example AB 12 34 56 C. The final letter is sometimes missing on documents.
Which prefixes are not used?
The letters D, F, I, Q, U and V are not used in the first position, and the second letter is never D, F, I, O, Q, U or V. The prefixes BG, GB, KN, NK, NT, TN and ZZ are not allocated.
Can it tell me if a number is real?
No. It only checks that the number is in a form that could be valid. Only HMRC can confirm a number belongs to a person.
Where do I find my number?
It is on your payslip, P60, P45, and letters from HMRC or the Department for Work and Pensions. You can also find it through your personal tax account on GOV.UK.