Getting a National Insurance number: the UK's answer to your Social Security number

Apply online once you're in the UK, start work as soon as you can prove your right to work, and check whether your eVisa already shows a number before you apply at all.

The short version

• It's like an SSN, with a twist. Your National Insurance (NI) number follows your UK pay, taxes and State Pension record. You apply for one online on GOV.UK, and only once you're physically in the UK [1][2].
• You may already have one. Many visa holders get an NI number automatically. Check the back of an old BRP or your eVisa in your UK Visas and Immigration account first [1].
• Don't wait to start work. You can start a job before the number arrives if you can prove your right to work [1].
• Your NI record builds a UK State Pension. You need 10 qualifying years for any new State Pension and 35 for the full rate, which is £241.30 a week (about USD 323) [3][4].
• Leaving later? The rules just got tighter. From April 6, 2026, voluntary Class 2 contributions from abroad ended for most people, and new Class 3 applicants need 10 years of UK residence or contributions [5].

What the NI number is (and isn't)

Back home in the States, your Social Security number does about ten jobs. In the UK, those jobs are split up. Your NI number is the reference HM Revenue and Customs (HMRC) and the Department for Work and Pensions use to log your National Insurance contributions, which build entitlement to the State Pension and some benefits. Your employer also uses it to report your pay and tax.

What it isn't: proof of your right to live or work in the UK. That's your visa, shown as an eVisa in your UKVI account. Employers check your right to work separately. And you don't need an NI number to rent an apartment, register with a GP or open most bank accounts, though some forms ask for one.

Like your SSN, guard it. Give it to your employer, HMRC and pension providers, and not much else.

Do you already have one?

Before you apply, look. GOV.UK says that if you have a BRP or eVisa, you might already have a National Insurance number [1]. Here's where to find it:

If none of that turns one up and you plan to work, you need to apply.

How to apply, step by step

The whole thing happens online now [2]. You can only apply when you're in the UK [1], and you must have the right to work and be working, looking for work or holding a job offer [1].

1. Get your passport ready. GOV.UK accepts a passport from any country, so your US passport works [2]. You can apply without one, but you may need an in-person appointment to prove your identity [2].
2. Go to the "Apply for a National Insurance number" service on GOV.UK. Watch out for lookalike sites that charge a fee. The real service is free.
3. Answer the questions about your address, immigration status and work.
4. Upload photos for the identity check. You'll take a photo of yourself holding your passport, plus photos of your other ID. A smartphone works, and someone else can take the pictures [2].
5. Save the reference number from the confirmation email. The email also tells you whether you need to provide more proof of identity [2].
6. Wait. It can take up to 4 weeks to get your number after you've proved your identity [2].

If you can't upload photos, you can still apply. It just takes longer, and you may be asked to book an appointment or post photocopies [2]. Stuck? The NI number helpline for England, Scotland and Wales is 0800 141 2079, Monday to Friday, 8 a.m. to 5 p.m. [2].

Working while you wait

This trips up a lot of Americans who assume "no number, no paycheck." Not so. GOV.UK says you can start work before you receive your NI number if you can prove your right to work [1]. Tell your payroll team you've applied. Your first paychecks may run on an emergency tax code, which can overtax you for a month or two, but that gets fixed once HMRC has your details. Keep your payslips, just as you would your W-2s back home.

Your State Pension record

Every year you pay enough NI (or get credited with it) counts as a qualifying year. Here's how the numbers work in 2026:

You can check your NI record and get a State Pension forecast through your HMRC online account or the HMRC app. It's worth a look once a year, the way you'd peek at your Social Security statement on my Social Security.

How the US–UK totalization agreement helps

The US and UK have a Social Security totalization agreement. Two pieces matter for Americans in London [6]:

• No double tax on a short assignment. If a US employer sends you to London temporarily, you may be able to keep paying into US Social Security instead of UK NI, with a certificate of coverage. Self-employed people attach a copy of that certificate to their US tax return every year [6].
• Combining credits. If you're short on credits in one country, you may be able to count work in the other. For a partial US benefit, you need at least six US credits before your UK coverage can be counted [6]. The SSA's Federal Benefits Unit at the US Embassy in London handles US benefit questions in the UK [6].

One more piece of good news: the Social Security Fairness Act, signed in January 2025, repealed the Windfall Elimination Provision, so a UK State Pension no longer shrinks your US Social Security check the way it once could. Our guide to Social Security abroad has the details.

Leaving the UK: voluntary contributions from abroad

Plenty of Americans spend five or eight years in London and then head home. If you leave with fewer than 35 qualifying years, you can sometimes fill gaps with voluntary contributions. The rules changed in 2026, so here's where things stand.

What changed on April 6, 2026

HMRC's policy paper sets out the changes [5]:

• Class 2 from abroad is gone for most people. The cheap Class 2 option (£3.65 a week in 2026–27, about USD 4.90) is now open from abroad only to a narrow group, such as self-employed people treated as UK self-employed under a social security agreement, and some volunteer development workers [5][7].
• Class 3 needs a longer UK link. New applicants to pay Class 3 from abroad must have 10 continuous years of UK residence or 10 qualifying years on their record. It used to be three [5].
• Transitional rules. People already paying Class 3 can carry on. People already paying voluntary Class 2 who apply for Class 3 before April 6, 2027, can still use the old three-year test [5].

Class 3 costs £18.40 a week in 2026–27 [7], about £957 a year (about USD 1,280). HMRC says it costs £767 a year more than Class 2 (about USD 1,030) [5].

Is it worth it?

It's a ballpark call. A year of Class 3 buys you roughly 1/35 of the full State Pension, every year for life once you reach State Pension age. For many people that pays back within a few years of retirement. But it isn't a no-brainer for everyone: if you'll never reach 10 qualifying years, extra voluntary years may not get you over the line. Check your forecast before paying anything, and apply to pay from abroad with HMRC's form CF83 or the online service.

You can usually only pay for the last six tax years, so don't let gaps sit too long. A US expat tax preparer (or a UK pensions specialist) can check your situation.

Don't forget the US side

• Uncle Sam still wants his return. UK NI contributions aren't deductible on your US return, and the totalization agreement, not the tax treaty, is what stops double Social Security tax.
• Keep your SSA account alive. Make sure you can still sign in to my Social Security from London. You'll want it at retirement.
• Enroll in STEP so the US Embassy in London can reach you in an emergency.

Have a question about your NI number or State Pension forecast? Ask other Americans in our community group for Americans in the UK.

USD conversions use the Federal Reserve H.10 rate of October 30, 2026 (USD 1.3398 per GBP).

Sources

1. Apply for a National Insurance number: who can apply, GOV.UK
2. Apply for a National Insurance number: how to apply, GOV.UK
3. The new State Pension: eligibility, GOV.UK
4. The new State Pension: what you'll get, GOV.UK
5. Voluntary National Insurance contributions abroad from 6 April 2026, HMRC policy paper
6. Agreement between the US and the UK, Social Security Administration
7. Voluntary National Insurance: rates, GOV.UK

Keep reading

• UK taxes for Americans: how they fit with your US return
• UK pensions and US tax
• Social Security abroad: payments and restrictions
• Tax treaties and totalization agreements