This is an UK National Insurance Number validation tool, you can enter the appropriate value to get the verification results, for the convenience of use, the tool provides a generator, you can use the generator to test the results.
The format of the NINO number is two prefix letters, six digits, and one suffix letter. The example used is typically BN102966C. Often, the number is printed with spaces, like this: BN 10 29 66 C.
The prefixes ZZ, NT, TN, KN, BG, NK, and GB are not allocated. Neither of the first two letters can be D, F, I, Q, U or V. O can't be the second letter.
To remember this is so difficult, use the tool validate the an number.