UTR and National Insurance Number Explained
Two numbers you'll hear about constantly when you're self-employed: your UTR and your National Insurance number. Here's what they are and why they matter.
What is a UTR?
UTR stands for Unique Taxpayer Reference. It's a 10-digit number that HMRC uses to identify you for Self Assessment purposes.
Example UTR format:
1234567890
When do you get one?
You'll receive a UTR when you:
- Register for Self Assessment, OR
- Set up a limited company
HMRC sends it by post, usually within 10 working days of registration. You can also find it on previous tax returns or in your HMRC online account.
Why is it important?
- You need it to file your Self Assessment return
- You need it to log into the HMRC online portal
- Accountants will ask for it
- Some clients/agencies may request it
Keep it safe
Your UTR is sensitive information. Don't share it publicly. Treat it like a bank account number.
What is a National Insurance Number?
Your National Insurance (NI) number is a unique identifier used across the UK benefits and tax system. Everyone who works in the UK has one.
Example NI format:
QQ 12 34 56 C
It's made up of:
- Two letters
- Six numbers
- One letter (A, B, C, or D)
When do you get one?
Most people get their NI number automatically when they turn 16 (if they have a parent claiming Child Benefit). Otherwise, you apply for one when you start working.
Why is it important for self-employment?
- It tracks your National Insurance contributions
- Contributions build up your State Pension entitlement
- You need it for your Self Assessment return
- HMRC links it to your tax records
UTR vs NI Number: Quick Comparison
| UTR | NI Number | |
|---|---|---|
| Format | 10 digits | 2 letters + 6 digits + 1 letter |
| Purpose | Self Assessment tax | All tax and benefits |
| When issued | When you register for SA | Age 16 or when you start work |
| Who has one | Self-employed, company directors | Everyone who works in UK |
How to Find Your UTR
- Previous tax returns – It's on the front page
- HMRC letters – Most correspondence includes it
- HMRC online account – Log in and check your details
- Call HMRC – They can tell you over the phone (after security questions)
How to Find Your NI Number
- Payslips – Usually shown on employee payslips
- P60 – End of year certificate from employer
- HMRC app – The official app shows it
- NI letter – The original letter sent when you were 16
- Request a reminder – Via gov.uk if lost
What If You Don't Have a UTR?
If you're newly self-employed, you need to:
- Register for Self Assessment on gov.uk
- Wait for your UTR to arrive (up to 10 working days)
- Then set up your Government Gateway account
Don't leave this until the last minute. Register as soon as you start self-employment.
Common Questions
Can I have more than one UTR?
Yes, in some cases. A sole trader UTR is different from a company UTR. Make sure you use the right one.
Is my UTR the same as my company number?
No. Company number is issued by Companies House. UTR is from HMRC. They're separate.
Can someone steal my identity with these numbers?
They're sensitive but not enough on their own. However, treat them carefully – don't post them publicly.
This article is for general information only. It's not financial or tax advice. Always check HMRC guidance and speak to a professional if you're unsure.