What is a National Insurance (NI) number, is it required before starting work, and how do I get one?

This post is general information, not legal or immigration advice. The facts come from the GOV.UK pages listed below (as of October 2026).

Who does this apply to?

• This is for adults who work, or want to work, in England. GOV.UK has a separate section for people aged 19 or under.
• The general conditions GOV.UK gives: you live in the UK, you have the right to work in the UK, and you are working, looking for work or have a job offer.

Details

• What is it? It is made up of 2 letters, 6 numbers and a final letter. GOV.UK says it stays the same for life.
• What is it for? So that your tax and National Insurance contributions are recorded under your name only. Contributions matter for the State Pension and some benefits.
• Is it required before starting work? The official page says you can start work before the number arrives, if you can prove your right to work. The same site says you will usually need the number when you start a new job, and that your employer needs it to pay you.
• You may already have one. If you already have a number, you do not need to apply for a new one, even if your details change. People with a BRP (biometric residence permit) or an eVisa (digital immigration record) can find it on the back of the BRP or in their UKVI account.

How to apply

1. Apply online through the GOV.UK NI number page. You can only apply while you are in the UK.
2. Have a passport (any country) or an EU, Norway, Liechtenstein or Switzerland national ID card ready.
3. Upload a photo of yourself holding your passport and photos of your other ID documents. Someone else can take the photos.
4. You get an email after you apply. Your application reference number is in that email.
5. It can take up to 4 weeks to get the number after your identity has been proved. This is GOV.UK's current estimate.

If you have no passport or cannot upload photos

You can still apply. But you may need an in-person appointment to prove your identity. If you cannot upload photos, it takes longer, and you may need an appointment or to post photocopies. Instructions come by email.

Tax code and emergency tax

• If your new employer lacks enough earlier details, you may be put on an emergency tax code. These end in W1, M1 or X, and you may see NONCUM on a payslip.
• With this code, tax is based only on that week's or month's pay, so the amount may be wrong.
• HMRC usually updates the code once it has details from your new and previous employers. This can take up to 35 days after you start. A P45 from your previous job can help. If you paid too much tax, you can claim a refund.
• If your code still looks wrong after 35 days, the GOV.UK emergency tax codes page explains how to check it online and how to contact HMRC.

Things to watch

• A general tip (not stated on the GOV.UK apply page): before giving details or money to any other site, check that you reached it from the official GOV.UK page.
• The NI application helpline is for new applications. GOV.UK says HMRC cannot give you a lost NI number over the phone or on webchat. See the GOV.UK lost number page.
• Waiting times and helpline hours can change.

What you can do

• NI application helpline (England, Scotland, Wales): 0800 141 2079, Monday to Friday, 8am to 5pm. Northern Ireland: 0800 587 0024, Monday to Friday, 9am to 4pm.
• GOV.UK says you can call if you applied more than 4 weeks ago, have moved or your details have changed. Have your application reference number ready.
• For questions about your right to work or immigration status, see GOV.UK's Find an immigration adviser page. It says you cannot get your money back if an adviser is not regulated.
• Questions to ask the official body: Do I need an appointment to prove my identity? What stage is my application at? What does my employer need from me until the number arrives? When will my tax code be updated?