What is a National Insurance Number

Your national insurance number is often shortened to ‘NINO’.

Here’s everything you need to know about your national insurance number, why it’s important for tracking how much national insurance you have paid and where you can find it.

What is a National Insurance Number

A national insurance number is a code assigned to each worker in the UK.

It is usually issued just before someone’s 16th birthday, ready for them once they start work. Or someone can apply for one when they move to the UK.

It helps the government to keep a check on each person’s right to each of the state benefits.

It helps to think of your NINO like a bank account number.

HMRC and the DWP use your number to create a record where they can monitor accurately what NI you have paid so they can work out what state benefits you are entitled to and how much.

Every number is unique to each individual in the UK and it stays the same regardless of your age or marital status and even if you leave the country for periods of time.

The Number Format

Every NINO follows a specific format – 2 letters, 6 Digits and 1 Letter

Here is an example: AA 123456 C

The prefix – AA in the example above – is chosen randomly and used until all the numerical digits are used up.

The following prefixes are not used:

  • BG
  • GB
  • KN
  • NK
  • NT
  • TN
  • ZZ

The suffixes – C in the example above – actually serves no purpose! It dates back to times when contributions were recorded manually and paid over quarterly.

So the suffixes A, B, C and D denoted payments for the four quarters of the year.

Where to Find Your NINO

If you have been issued with your number and need to find it, then there are several places you can look, such as:

  • National Insurance Number Card (if you were issued with one);
  • Payslips;
  • P45 or P60;
  • Personal tax account

How to Find a Lost National Insurance Number

If you cannot find your National Insurance Number then you can either write or call HMRC.  Here’s how:

By Post

Fill out the online form CA5403 here. Then print and post it to HMRC.

By Phone

Contact the UK NINO Helpline on 0300 200 3500.

You will have to get through security checks and they will then post a copy of your number to you.

Due to the confidential nature of your National Insurance Number, it will not be given to you over the phone. Any reminders will be sent out to you by post and can take up to 15 working days.

If you still have questions or are unsure of any details then contact the NINO Helpline on 0300 200 3500.

Should you keep your national insurance number secret?

Your NINO is a highly confidential piece of information and you should not share it with anyone except for:

  • your employer
  • HMRC
  • Department of Work and Pensions (DWP)
  • Student loans company

It is a unique reference to you and if you share it with the wrong person they could use it to steal your identity.

Anita Forrest
About Anita Forrest

Anita Forrest is a Chartered Accountant, spreadsheet geek, money nerd and creator of www.goselfemployed.co - a UK small business finance blog where she shares help and advice with the self-employed community to make topics like registering a business, bookkeeping and taxes easy to understand.