Skip to main content
Guidance

Apply for a refund of Class 1 National Insurance contributions

If HMRC has sent you a letter telling you that you may be due a refund of Class 1 National Insurance, check how to apply.

Class 1 National Insurance contributions are usually paid through your wages by your employer.

You can only apply if you’ve received a letter from HMRC telling you that you may be due a refund.

How you apply depends on whether your letter includes a claim reference number.

If your letter has a claim reference number

If your letter has a claim reference number, you can apply online or by post.

Your claim reference number is not your National Insurance number. You’ll find it at the top of the letter, underneath your National Insurance number, shown as ‘Reference’.

Apply online

Use the online service to apply for a refund of National Insurance contributions.

You’ll need:

  • your claim reference number from your letter
  • your bank or building society account details

You’ll need to sign in to use this service. If you do not already have sign in details, you’ll be able to create them.

If you’ve had more than one refund letter, make a separate claim for each one.

Apply by post

Fill in the CA4361 form sent to you and send it to the address shown on the letter.

If your letter does not have a claim reference number

Without a claim reference number, you can only apply by post. Fill in the form sent to you and send it to the address shown on the letter.

If you’ve lost the form sent to you, contact the National Insurance helpline.

If you have not received a letter

If you think you’re owed a refund, check how to claim your National Insurance refund.

What happens next

HMRC will check your application and write to you with the outcome.

You can check when you can expect a reply from HMRC.

Updates to this page

Published 5 February 2024
Last updated 10 August 2026 Show all updates
  1. Guidance updated to explain how to apply for a refund of Class 1 National Insurance contributions and when to apply by post using form CA4361. You can only apply online if your letter includes a claim reference number.

  2. A new section — ‘Who can use this form’, has been added to help you choose the correct refund form depending on what’s included in your letter from HMRC.

  3. A link has been added to find out when you can expect to receive a reply from HMRC to a query or request you've made.

  4. First published.

Sign up for emails or print this page