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What is a National Insurance number?

February 4, 2022
Whether it’s applying to a full-time position alongside your side-hustle or filing your Self Assessment tax return, your National Insurance number will come up time and time again when finalising these important documents.
But what exactly is a National Insurance number, and why do I need one? We’ll be answering all your questions about your National Insurance number below.

What is a National Insurance number?

Composed of 2 letters, 6 numbers and a final letter at the end, a National Insurance number (otherwise referred to as an NI number) is a unique code that matches your National Insurance contributions (NICs) and tax records up against your name only.
You should automatically be given a National Insurance number if you are a UK citizen just before you turn 16, and this is the number that will be assigned to your tax record for the rest of your life.As a result, you cannot request a new National Insurance number if you lose yours, so be sure to keep yours safe to protect yourself from identity fraud.Despite your National Insurance number being unique to you, you cannot use it as a form of identification in the same way you would use a driving licence or birth certificate.

Why do I need a National Insurance number?

Alongside keeping track of your tax records, your National Insurance number is used by the following:
    HM Revenue and Customs (HMRC)Department for Work and Pensions if you claim state benefits, or the Department for Social Development if you’re in Northern IrelandYour local council or the Northern Ireland Housing Executive if you’re claiming Housing BenefitElectoral Registration Officers to verify your ID when you register to voteThe Student Loan Company when you apply for a student loanYour pension provider if you have a personal or stakeholder pensionYou Individual Savings Account (ISA) provider if you open an ISAAuthorised financial service providers who help you buy and sell investments like shares, bonds and derivatives

Can I work if I don’t have a National Insurance number?

While it is a legal obligation to have a National Insurance number to work in the UK, you can start working while you wait to receive yours — but be sure to apply as soon as possible to avoid getting into difficulty with HMRC further down the line.If you do start working before receiving your National Insurance number, you’ll need to verify that you have a right to work in the UK. You’ll also need to fill out the Starter Checklist so your employer can add you to the payroll as soon as possible.If you’re self-employed, ideally you’ll need to have your National Insurance number to hand before submitting your Self Assessment tax return. If you don’t have your number due to a delay in your application, you can still submit and tell HMRC why the National Insurance number box is blank — just make sure that you don’t miss the Self Assessment deadline.

How do I get a National Insurance number?

As mentioned above, if you are a UK citizen you should receive your National Insurance number 3 months before you turn 16. However, if you don’t have one and are looking to start working in the UK, you can apply for a National Insurance number through HMRC.

How do I apply for a National Insurance number?

Before you start the application process, you’ll need to make sure you are eligible. To be classified as eligible, you must not fall under one of the following:
    Looking to replace a lost National Insurance numberAre a UK resident aged 19 or under — you can call HMRC and request to have one sent to youHave a biometric residence permit (BRP) that already has a National Insurance number printed on itAre only applying for a National Insurance number because you want to apply for benefits or a student loan
Aside from the above criteria, if you are looking for work, have an offer to work, have started to work or are living in the UK and have a right to work, you should be able to begin the application process.To start the application, you’ll need to make sure you have at least one of the following to hand:
    A passport from any countryA biometric residence permit (BRP)A national identity card from a country in the EU, Norway, Liechtenstein or Switzerland
You can still apply if you do not have any of the above, but you may need to attend an appointment to prove your identity. With this in mind, you can begin the application through the application portal.

After you apply, you’ll get an email with your application reference number telling you if you need to provide any further information. The process, unfortunately, won’t be immediate — you might have to wait up to 16 weeks to get your National Insurance number after you have proven your identity.

Where can I find my National Insurance number?

If you already have your National Insurance number, you can find it on the following documents:
    Your payslipYour P60On letters about your tax, pension or benefitsIn the National Insurance section of your personal tax account

If you’ve lost your National Insurance number

As mentioned above, since your National Insurance number is unique to you and your tax records, you cannot apply for a new number if yours is lost.If you do not have any of the documents above close to hand, you can fill in form A5403, or contact the National Insurance helpline, where you might be asked to fill in form CA5403. Once you’ve filed your request, you can expect to receive your National Insurance number in the post within 15 days.