A National Insurance (NI) Number is a unique reference code that tracks your tax and National Insurance contributions in the UK. You need one to work legally, pay taxes, and access state benefits. Every immigrant who works or plans to work in the UK must apply for one. The good news: the application is free, straightforward, and now done entirely online.
What is a National Insurance Number?
Your National Insurance Number is a unique identifier in the format: two letters, six digits, one letter — for example, AB 12 34 56 C. It is used by HMRC (the UK tax authority) and the Department for Work and Pensions (DWP) to record your tax payments, National Insurance contributions, and entitlement to state benefits such as the State Pension.
- You need it to start any paid employment in the UK
- Employers use it to process your payroll correctly
- It ensures you pay the right amount of tax and National Insurance
- It is required to claim benefits, tax credits, or student loans
- It is used to access government services and build entitlement to the State Pension
- You keep the same NI number for life — it does not change if you renew your visa or become a citizen
Can you start work before you have your NI number?
Yes — you can legally start work in the UK without an NI number, as long as you have the right to work. Your employer can pay you while you are waiting for your number, and you can give them the number once it arrives. Tell your employer you have applied and provide the application reference. HMRC will allocate any tax paid in the meantime to your record once your number is issued.
💡 Tip
If your employer is insisting on an NI number before your first day and you do not have one yet, show them the HMRC guidance stating that employees can legally start work without one. The requirement is to have the right to work — not the NI number itself.
How to apply for a National Insurance Number
Since 2022, the NI number application process is done entirely online. There is no longer a face-to-face interview required for most applicants.
- Step 1: Go to gov.uk/apply-national-insurance-number
- Step 2: Click "Apply online" — you will need to verify your identity using the HMRC app or by uploading documents
- Step 3: Answer questions about your right to work in the UK and your circumstances
- Step 4: Upload evidence of your identity and right to work (passport and BRP/eVisa share code)
- Step 5: Submit the application — you will receive a confirmation email with your application reference
- Step 6: Wait for your NI number — it is usually sent by letter within 2–4 weeks
- Note: Some applicants may be invited for a telephone interview if the automated process cannot verify their identity
What documents do you need?
- Valid passport (any nationality)
- Proof of your right to work in the UK: BRP, eVisa Share Code, or valid visa in passport
- UK address — you must have a UK address where the NI number letter can be sent
- If you have recently arrived: your arrival date and port of entry may be requested
How long does it take?
In 2025, most online applications are processed within 2–4 weeks. The NI number is sent to you by post in a letter from HMRC. In some cases — particularly if there are questions about identity or right to work — it can take up to 16 weeks. If you have not received your number after 12 weeks, call the NI application helpline on 0800 141 2075.
Your NI number and your tax code
Once HMRC issues your NI number, make sure you give it to your employer. HMRC will also assign you a tax code (such as 1257L, which is the standard code for the 2025/26 tax year). If you are on an emergency tax code (such as 1257L W1 or M1), you are being taxed on a week-by-week basis without the benefit of the full personal allowance. Giving your NI number to your employer and to HMRC will correct this.
💡 Tip
Keep your NI number private and secure — it is as sensitive as your passport number. Never share it in response to an unsolicited phone call, email, or text message. HMRC will never ask for payment over the phone.