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A National Insurance number, also known as an NI number, is used to make sure that UK workers pay the right amount of National Insurance and Income Tax. Each NI number is unique, and relates to just one person.

What is National Insurance?

National Insurance is a type of financial contribution you make on the money that you earn. Making NI contributions helps you qualify for certain benefits and the State Pension.

It also pays for medical services and people who are ill, retired or unemployed.

The amount that you pay depends on how much you earn, and whether you work for yourself, an employer, or both.

Do I need an NI number to work?

You do need a National Insurance number to work in the UK, even if you work for yourself. This is to help keep track of the contributions you make towards your National Insurance record.

Watch our video to learn more about income tax and National Insurance if you work for yourself.



Paying NI is mandatory (a requirement) once you’re over the age of 16, and your earnings reach the income threshold to start paying National Insurance.

Your NI number will usually be sent to you by post shortly before your 16th birthday.

If you don’t receive one, or you came into the UK later, then you can apply for an NI number online.

What does a National Insurance number look like?

A National Insurance number consists of two letters, followed by six digits, and then one letter as a suffix, e.g. AB 12 34 56 C

Although the first two letters and the six digits of a National Insurance number are unique to each individual, the last letter will be either A, B, C or D.

Up until 1984, a person was sent their National Insurance number on a notification card, similar to a postcard. From 1984 until 2011, this was sent as a plastic card, similar to a debit or credit card.

Since 2011, National Insurance numbers are sent through the post in a letter. This is an important document to keep, as you’ll need to refer to it multiple times throughout your life.


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What happens if I lose my NI number?

You’ll usually be able to find your National Insurance number on any payslips or tax documents you have, such as a P45 or P60. If you don’t have these, or still can’t find it, contact HMRC, so they can resend it to you.

What if I stop working?

If you’re a carer, or are too ill to work, you may be eligible for National Insurance credits so that you don’t have gaps in your NI record. This means that the amount of pension or benefits you can access, won’t be affected.

If you are unable to claim National Insurance credits, you may want to pay voluntary National Insurance Contributions.

Get help with your National Insurance and income tax from one of the team, and learn more about our online accountancy services. Call 020 3355 4047, or get an instant quote.

About The Author

Beth-Anne Bruce

I'm an experienced and fully AAT and ACCA qualified accountant, who is enthusiastic about helping business owners succeed. I also love cooking and needlepoint (at different times!). Learn more about Beth.

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