Form

Get your National Insurance number

Use your personal tax account to view your National Insurance number or download a letter confirming it, or use form CA5403 to get your number by post.

Documents

View your National Insurance number online (sign in using Government Gateway)

Apply by post (using form CA5403)

Details

If you already have a National Insurance number

If you’ve forgotten your National Insurance number or need a letter confirming it, you can use your personal tax account to view or download, print, save or share a letter with it on.

To view your National Insurance number online, you need a Government Gateway user ID and password. If you do not have a user ID, you can create one when you use the service.

If you do not have a personal tax account, you can register for one now.

If you’re unable to register for a personal tax account

Fill in form CA5403 on-screen, then print and post it to HMRC.

Depending on the answers you give, you may also need to send other documents to confirm your identity to HMRC. It will tell you after you fill in the form if you need to send other documents.

You may need to send up to 2 of the following documents:

  • birth certificate
  • passport
  • full or provisional driving licence
  • adoption certificate
  • home office or travel document
  • work permit
  • certificate of naturalisation
  • marriage or civil partnership
  • certificate of service in Her Majesty’s Forces or merchant navy
  • identity or medical card

It can take up to 15 days to get your National Insurance number by post.

Send the print and post form to:

National Insurance contributions and Employers Office
HM Revenue and Customs
BX9 1AN

Before you start using the CA5403 postal form

If you’re using an older browser, such as Internet Explorer 8, you’ll need to update it or use a different browser. Find out more about browsers.

You’ll need to fill in the CA5403 fully before you can print it. You cannot save a partly completed form so gather all your information together before you start to fill it in.

If you do not have a National Insurance number

You can apply for a National Insurance number if you’ve never had one.

Published 9 April 2014
Last updated 21 January 2019 + show all updates
  1. Form CA5403 has been updated with details about which documents you may need to send to confirm your identity to HMRC if you're unable to register for a personal tax account.
  2. Guidance updated as you can now use your personal tax account to view or download, print, save or share a letter with your National Insurance number on.
  3. Updated form CA5403 to provide HMRC with enough information to confirm a NINO.
  4. An online service is now available.
  5. Amended postal address to: National Insurance Contributions and Employer Office, HM Revenue and Customs, BX9 1AN.
  6. Added translation