The short answer
Your UTR (Unique Taxpayer Reference) is a 10-digit number, sometimes just called your "tax reference". gov.uk says it usually arrives by post around 15 days after you register, and takes longer if you live overseas. A late UTR doesn't always move your deadline: if you registered after 5 October 2026, your return date moves but you must still pay by 31 January 2027.
Check your dates
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What moves if your UTR is late
| You registered | HMRC's letter or email is dated | Return due | Payment due |
|---|---|---|---|
| By 5 October 2026 | By 31 October 2026 | 31 January 2027 | 31 January 2027 |
| By 5 October 2026 | After 31 October 2026 | 3 months from the letter | 3 months from the letter* |
| After 5 October 2026 | After 31 October 2026 | 3 months from the letter | 31 January 2027 |
*From the Taxes Management Act 1970, section 59B(3). gov.uk's deadlines page doesn't spell this case out, so confirm the date with HMRC before relying on it. The return rows are from section 8, for online returns. Registered after 5 October with a letter dated before 1 November? Section 8's 3-month rule doesn't apply, though gov.uk's page says only "3 months from the date on the letter", so go by what your letter says.
Three months counts from the letter's date, not the day it reaches you. If your bill isn't all paid by 31 January and you registered late, you may also get a failure to notify penalty, based on what's left to pay.
Look for it online first
gov.uk lists these places to find an individual's UTR. It doesn't say how soon a new one appears there, so it may not beat the post.
- The HMRC app
- Your personal tax account
- Earlier returns and HMRC documents, such as notices to file or payment reminders, if you've registered before. You may need to reactivate your account.
Check HMRC's reply times
HMRC's reply times tool covers Self Assessment and UTRs and is updated weekly. Use it rather than relying on the 15 days.
How to chase it
If that date has passed, contact Self Assessment general enquiries:
- Phone: 0300 200 3310, Monday to Friday, 8am to 6pm, closed bank holidays (+44 161 931 9070 from abroad).
- Online: HMRC's digital assistant helps with registering, and can pass you to a webchat adviser if one is available.
Have your registration date to hand. Note who you spoke to and when, and keep any confirmation of the date you registered. If a penalty does arrive, that's what you'd point to in an appeal, though we can't say whether one would succeed.
Can you pay before the UTR arrives?
We couldn't confirm that you can. gov.uk's payment reference is your UTR followed by the letter K, on every payment method we read, and we found no gov.uk route for paying without one. gov.uk warns that a wrong reference can delay your payment or put it against another bill, so don't guess one.
If 31 January is getting close and you have no UTR:
- Ask HMRC how to pay when you chase, and say you need to pay by 31 January.
- Set the money aside now, so you can pay the day the number comes. The calculator estimates the bill.
- Can't pay it all? See what to do if you can't pay.
Use the wait
You can't file online without the UTR, but you can get everything else ready: your sales, fees and costs for 6 April 2025 to 5 April 2026. A spreadsheet you set up yourself works fine. If you'd rather not build one, our bookkeeping spreadsheet for online sellers (£12.99, Excel or Google Sheets) totals your tax year. It's made by the same people as this site and is optional.
Common questions
How long does a UTR take to arrive?
gov.uk says you'll usually get your UTR by post around 15 days after you register, and longer if you live overseas. HMRC's reply times tool covers Self Assessment and UTRs and is updated weekly.
What should I do if my UTR hasn't arrived?
Check the HMRC app and your personal tax account, which gov.uk lists as places to find it. Check HMRC's reply times tool. If that date has passed, contact Self Assessment general enquiries on 0300 200 3310, Monday to Friday, 8am to 6pm, or use HMRC's digital assistant.
Can I file my tax return without a UTR?
Not online through HMRC's service. gov.uk says you'll need your UTR to file. If you registered after 5 October 2026, HMRC's letter or email gives you a different return date, 3 months from the date on it.
Can I pay Self Assessment without a UTR?
gov.uk's payment reference is your UTR followed by the letter K, and we found no gov.uk route for paying without one. Don't guess a reference, because gov.uk warns a wrong one can delay your payment. Ask HMRC how to pay, and set the money aside.
Does the 31 January payment deadline move if my UTR is late?
If you registered after 5 October 2026, no: gov.uk says you must still pay by 31 January 2027. If you registered by 5 October and HMRC's notice is given after 31 October, the Taxes Management Act gives you 3 months from the notice to pay. Confirm that with HMRC before relying on it.
Where can I find a UTR I've lost?
gov.uk lists your personal tax account, the HMRC app, and earlier returns and HMRC documents such as notices to file or payment reminders. It's a 10-digit number and may just be called your tax reference. If you can't find it, contact HMRC.