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HMRC internal manual

National Insurance Manual

HM Revenue & Customs
, see all updates

National Insurance Numbers (NINOs): Format and Security: Why security of the NINO is important

The NINO is not proof of identity and must not be accepted as such. It must not be used by anyone else other than:

  • for the purposes described at NIM39125, or
  • as authorised by HMRC or DWP.


The NINO is sometimes mistakenly seen as a means of identity and entitlement to work. NINOs can be in great demand and can be stolen and sold on, for example for use by people who may not have permission to take up legitimate employment, or those people working and also claiming benefit. Multiple, fraudulent benefit claims are another use for stolen NINOs.

What can we do about it? See NIM39140.