I have lost my National Insurance number. What do I do? (2024)

You will normally be sent a National Insurance (NI) number, which looks something like AB123456C, just before your 16th birthday.

You'll only ever be issued with one NI number, and it stays the same for life. It keeps a record of your National Insurance contributions, which over your working life can entitle you to some benefits and a state pension.

It's important to keep it safe, like you do with other important personal data. Any employer you have will need to know it so that they can pay your contributions correctly. And you will need it if you want to talk to HMRC about tax and benefits, or when applying for things like a driving licence, ISA savings account or student loan.

But if you've lost your NI number, it's not the end of the world. There are several ways to find it again:

Find it online

You can check your number using your online Personal tax account or on the HMRC App. When you go online, you’ll be asked some questions to start with, to confirm who you are. Don’t worry if you can’t get into it on your first attempt, you can try again later. Once you’re in you can view, share or print a copy of your NI number confirmation letter.

This HMRC video shows you how to access it:

Look back through old records

You'll find your NI number on many documents that you will have received from your employer or HMRC. Check old payslips, P60s, or any letters about tax, pensions and benefits.

Request it by post

Complete an online form on the HMRC site and they'll post you your NI number again. There's also a HMRC phone line that can send your number by post if you would rather do that - see the National Insurance Number Helpline for more. 

Getting a number sent by post can take up to 15 days.

Be alert to scam companies that promise to provide your national insurance number online in return for a fee. Getting your national insurance number is free and it is issued by HMRC.