What is a national insurance number?
Answered 11 March 2026
What is a National Insurance Number?
HMRC guidance / practice
A National Insurance number (NINO) is a unique personal reference number allocated to each National Insurance contributor by the National Insurance Contributions Office (NICO).
Format: A NINO consists of two letters, followed by six numerals, followed by one letter — for example: AB 12 34 56 C. Another example format given in HMRC guidance is DQ 12 34 56 A.
Where to find it: Your NINO can be found on:
- Your National Insurance card
- Letters from Social Security
- Documents sent to you from HMRC
- Pay slips
- Forms P45 or P60
Why it matters: A NINO is required for various tax and administrative purposes — for example, HMRC cannot register an individual for Self Assessment without a valid NINO, and pension scheme administrators must supply a member's NINO when completing Event Reports or Accounting for Tax returns.
Note: Not everyone qualifies for a NINO. Where an individual does not qualify, alternative arrangements may apply (e.g. an 'alternative identifier' in the context of pension schemes).
Citation sources
Where an individual gives the scheme administrator written confirmation that they do not qualify for a National Insurance number the scheme administrator should obtain an ‘alternative identifier’ from Pension Schemes Services. Follow the guidance in the section ‘If the individual is not entitled to a NINO’ at PTM161200. Where the scheme administrator doesn’t know the member’s National Insurance number, that is, they haven’t been told that the member doesn’t qualify for one, the scheme administra
n the National Insurance and PAYE Service on which the Expat Indicator is recorded you should note SA1 ‘PAYE Service record shows expat indicator’ and forward it to Specialist PT Manchester Expat Team High Net Worth Unit Cases (HNWU). These cases will not be immediately identifiable. However, if after tracing you find the customer has an SA record where the CPR signal is set, refer the SA1 to the HNWU Unsolicited Returns. These will not be dealt with by CAAT, regardless of whether they are accom
Regulation 11C The Registered Pension Schemes (Provision of Information) Regulations 2006 - SI 2006/567 The scheme administrator needs to supply HMRC with details of a member’s National Insurance number when they complete an Event Report or an Accounting for Tax return. If a scheme administrator asks the member for details of their National Insurance number, within 60 days of the scheme administrator’s request the member must provide the scheme administrator with either: their National Insurance
Each National Insurance contributor is allocated a unique reference, a National Insurance number (NINO), by the National Insurance Contributions Office (NICO). A NINO consists of two letters then six numerals then one letter. For example AB123456C