Check Your National Insurance Number Online: HMRC App or Tax Account

To check your National Insurance number online, sign in to your Personal Tax Account on GOV.UK or open the HMRC app on your phone. The number appears on screen within a couple of taps, and you can download a confirmation letter as a PDF from the same place. It takes about five minutes once you’re signed in, and the number itself never changes, so save it somewhere secure once you have it.¹

Check It Through Your Personal Tax Account

Go to the Personal Tax Account page on GOV.UK and sign in. If you already have Government Gateway credentials, use those. GOV.UK One Login is gradually replacing Government Gateway across government services, so you may be directed to sign in that way instead.¹²

Setting up a new account means proving your identity first. You’ll normally need photo ID: a UK passport, a UK photocard driving licence, a non-UK passport with a biometric chip, or a UK biometric residence permit. Some documents, including biometric residence permits, can still be used for up to 18 months after their expiry date.³

Once you’re in, look for the option to find your National Insurance number. It appears on screen, and you can download a confirmation letter as a PDF to save or print for an employer.¹

Use the HMRC App on Your Phone

The official HMRC app gives you the same access from a mobile device. Download it from your app store and sign in with the credentials you use for HMRC online services. After the first sign-in, you can switch to a six-digit PIN, fingerprint, or facial recognition for faster access.⁴

Inside the app, you can view your National Insurance number and save it to your phone’s digital wallet. That’s useful if you’re starting a new job and need the number on the spot. The app also handles tasks like updating your address and checking your tax code, so it’s worth keeping installed.⁴

If You Can’t Sign In Online

Before wrestling with sign-in problems, check whether you already have the number on paper. It’s printed on several documents most people have at home:

Payslips from most employers.
Your P60, the annual tax summary from your employer.
Your P45, issued when you leave a job.
Letters from HMRC about your tax code, tax credits, or benefits.
Benefit statements from the Department for Work and Pensions, such as Universal Credit or Jobseeker’s Allowance letters.

An old plastic National Insurance card still shows a valid number. HMRC stopped issuing the cards in 2011, and the number on them remains correct regardless of age.⁵

If you have no documents and can’t get online, contact HMRC and ask for a confirmation letter by post. HMRC will not give the number out over the phone or through webchat. The letter takes up to 10 working days to arrive in the UK, or up to 21 working days abroad.⁵

The National Insurance enquiries helpline is 0300 200 3500, open Monday to Friday from 8am to 6pm and closed on bank holidays. If you cannot hear or speak on the phone, use Relay UK by dialling 18001 then 0300 200 3500. Have your personal details ready, because HMRC will verify your identity before arranging the letter.⁶

Keep Your Address Current With HMRC

Your National Insurance number never changes, but the details attached to it can go out of date. If you’ve moved house or changed your name, tell HMRC so any confirmation letters actually reach you. You can update your name or address by signing in at GOV.UK or through the HMRC app. If you submit a Self Assessment tax return, your details update automatically when you report the change on it.⁷

This matters most for anyone relying on a posted confirmation letter. HMRC sends it to whatever address they hold on file, and they won’t redirect it over the phone.

Watch Out for Scams

Scammers regularly impersonate HMRC through phone calls, texts, and emails. A common approach is a message claiming there’s a problem with your National Insurance number, or offering a tax refund in exchange for your personal details. HMRC will not ask for personal or financial information by text, and will not ask you to share your National Insurance number through unsolicited contact.⁸

Forward suspicious texts to 60599 (network charges apply) or email them to phishing@hmrc.gov.uk, then delete them. The same email address works for suspicious emails. Someone with only your National Insurance number cannot open bank accounts or take out credit with it alone, but combined with other stolen information it can feed identity fraud, so treat it as sensitive.⁸

1
GOV.UK. Personal Tax Account: Sign In or Set Up
2
GOV.UK. Using Your GOV.UK One Login
3
GOV.UK One Login. How Users Can Prove Their Identity
4
GOV.UK. Download the HMRC App
5
GOV.UK. Find Your National Insurance Number
6
GOV.UK. National Insurance: Enquiries
7
GOV.UK. Tell HMRC About a Change to Your Personal Details
8
GOV.UK. Check if a Text Message You’ve Received From HMRC Is Genuine