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HMRC internal manual

National Insurance Manual

National Insurance Numbers (NINOs): Confirming a NINO: Confirmation by individual - Form CA5403

If someone cannot remember their NINO, they may find it on pay or benefit documents, for example a P60.

If a customer still needs to confirm their NINO, they should:

  • ring the National Insurance Registrations Helpline on 0300 200 3502, or
  • complete form CA5403 and send it to HMRC, National Insurance Registrations.


HMRC Action

If the customer rings the NI Registrations Helpline, they will determine the NINO where possible and issue a confirmation of NINO to the customer.

If the NINO cannot be found, or the customer cannot be helped on the telephone, they will tell the customer to complete form CA5403.

National Insurance Registration teams will deal with forms CA5403. They will confirm identity and update personal details and, where a NINO can be traced, will send a confirmation of NINO to the customer.

If a customer has never had a NINO, see NIM39325.