The National Insurance Number (NIN) is a unique number given to every person in the UK over the age of 16 who either works or receives benefits. It is composed of nine alphanumeric characters (like XX999999X), and is issued on a National Insurance card which is credit-card sized, turquoise on the top and red on the bottom.

National Insurance Numbers are issued by the Department of Work and Pensions, who operate local offices throughout the UK which are commonly called "Job Centres+".

There is a search engine which locates the nearest Job Center to a given place at Job Centre Location Search.