NIM39120 - National Insurance Numbers (NINOs): Format and Security: Use of NINO by outside bodies

The only official use of the NINO is as a reference number for HMRC and DWP but it is sometimes used by outside bodies and individuals for their own purposes. For example, banks or building societies sometimes use it to identify an individual to reduce fraudulent applications for mortgages or ISAs.

In most cases, requests to use an individual’s NINO for reasons other than the recording of NICs or claims to benefit should be refused, with an explanation that it's only purpose is as a reference number for HMRC and DWP. (This text has been withheld because of exemptions in the Freedom of Information Act 2000)