How to Find Your Lost National Insurance Number

Your National Insurance number is an important identifier you'll need for various tax and employment matters. If you've misplaced it, there are several straightforward ways to track it down without needing to apply for a new one. In most cases, you can find it within minutes by checking documents you already have or by accessing it online.

What does a National Insurance number look like?

Your National Insurance number is made up of 2 letters, 6 numbers and a final letter, for example, QQ123456B. Knowing this format can help you recognise it when searching through your documents.

Check documents you already have

Before requesting a new copy, check whether your National Insurance number is on documents you already have. You can find it on:

• Your P60 (the annual tax summary your employer gives you)
• Recent payslips
• Letters about benefits
• Your Apple or Google Wallet if you've previously saved it there

These are the quickest places to look, and many people find their number this way without needing to contact HMRC.

Find your National Insurance number online

If you can't locate it on existing documents, you can find your National Insurance number online through either your personal tax account or the HMRC app (for UK residents). Both services also allow you to download a letter showing your National Insurance number if you need it in writing.

Using the online service

You can use the online service if you:

• Need to find your National Insurance number
• Know your number but need it on a letter

To use this service, you'll need to sign in. If you don't already have sign-in details, you can create them during the process.

Important: HMRC will not tell you your National Insurance number over the phone or on webchat. You must use the online service or request it by post.

If you can prove your identity

If you can prove your identity online using documents such as a passport or driving licence, you'll be able to view your National Insurance number immediately on screen.

If you cannot prove your identity online

You can still use the online service even if you cannot prove your identity digitally. However, you won't be able to view your National Insurance number on screen. Instead, HMRC will post it to the address they have on record for you. This can take up to 10 working days to arrive.

If you live abroad

The online service is not available if you live abroad. You'll need to contact HMRC directly to request a letter confirming your National Insurance number. This can take up to 21 working days to arrive.

Request your National Insurance number by post

If you cannot find your National Insurance number on any documents and prefer not to use (or cannot use) the online service, you can request it by post using form CA5403.

To do this:

1. Fill in form CA5403 online

2. Print the completed form

3. Sign the declaration

4. Include any documents to confirm your identity

5. Post everything to HMRC

Important: You cannot save a partly completed form, so you'll need to complete it in one session before printing.

Send the completed form to:

National Insurance contributions and Employers Office

HM Revenue and Customs

BX9 1AN

If you live in the UK, the letter should arrive within 10 working days. If you live abroad, it can take up to 21 working days.

If you've never had a National Insurance number

The methods described in this article are for finding a National Insurance number you've already been issued. If you've never had a National Insurance number, you cannot use these services. Instead, you'll need to apply for one through a separate process.

Sources

• Find your National Insurance number
• Get your National Insurance number by post

This article provides general guidance based on current HMRC rules. For advice specific to your situation, speak to your accountant.