Everyone who wants to work in the UK must have a national insurance number. To obtain a national insurance number, you must be 16 or over and resident in Great Britain or Northern Ireland.
A national insurance number is unique to you and you keep the same one throughout your life. It is used to record the national insurance contributions and tax you pay and as a reference number by the Department for Work and Pensions and HM Revenue. You usually have to provide it when making benefits claims.
It is made up of 2 letters, 6 numbers and a final letter for example ZY 98 76 54 A.