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HMRC internal manual

National Insurance Manual

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

Customers can find National Insurance numbers on payslips, P60s, or letters about tax, pensions and benefits. If they have a personal tax account they can also view it there and print a confirmation letter.

If a customer still needs confirmation of their NINo, they should:

HM Revenue and Customs (HMRC) won’t tell you your National Insurance number over the phone. They’ll post it to you and it will arrive within 10 working days.

Further information is available at:


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.