Get your National Insurance number

View your National Insurance number or print a letter confirming it now using your personal tax account, or fill in form CA5403 to get your number by post.


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

Apply by post (using form CA5403)

CA5403 part 2: your documents

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If you already have a National Insurance number

If you’ve forgotten your National Insurance number or a letter confirming it, you can either:

  • use your personal tax account to view it
  • print a letter with it on now

If you do not have a user ID, you can register for one now.

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

Fill in the on screen form CA5403 part 1 on-screen, then print and post it to HMRC.

If you cannot give us all the information we’ve asked for in CA5403 part 1 you may have to fill in CA5403 part 2 as well. The CA5403 part 1 will tell you if you also need to print, then fill in CA5403 part 2. If you need to fill in both form send them back together.

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

Send the print and post form to:

National Insurance contributions and Employers Office
HM Revenue and Customs

Before you start using the CA5403 part 1 postal form

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You’ll need to fill in the CA5403 part 1 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 28 August 2018 + show all updates
  1. Updated form CA5403 to provide HMRC with enough information to confirm a NINO.
  2. An online service is now available.
  3. Amended postal address to: National Insurance Contributions and Employer Office, HM Revenue and Customs, BX9 1AN.
  4. Added translation