Sign in or create sign-in details, prove your identity if asked, and save your progress. Your UTR appears in your personal tax account within 72 hours.
Form SA1 by post
For people who are not self-employed and cannot register online, including anyone who does not live in the UK.
Reactivate an old record
Registered before but no return last year? You may need to reactivate your Self Assessment account rather than register again.
How to register with form SA1
1
Check you need a tax return
Check whether you need to send a Self Assessment return before you register.
2
Gather your details
You need your personal details and the reason you need to complete a tax return, for example Capital Gains Tax to pay or income from a trust.
3
Fill in, print and post SA1
Complete form SA1, print it, and post it to HMRC using the postal address shown on the form.
4
Wait for your UTR, then file
HMRC sends your Unique Taxpayer Reference by post. Registered by 5 October 2026? Your return is due by 11:59pm on 31 January 2027.
What SA1 asks for
GOV.UK lists two things you need to register by post.
Your personal details
Your personal details. Once you are registered, HMRC gives you a Unique Taxpayer Reference (UTR).
Why you need to complete a tax return
The reason you are registering, for example because you need to pay Capital Gains Tax or you receive income from a trust. GOV.UK's route also gives income from a pension or a property as examples.
Timing traps GOV.UK warns about
Registering after 5 October 2026: you could get a penalty.
Registering late also moves your filing deadline: HMRC sends a letter or email with a deadline 3 months from its date.
A late registration does not move the payment date: the tax you owe is still due by 31 January 2027.
After you register
Send your Self Assessment return by the deadline and pay your bill by 11:59pm on 31 January 2027. If your UTR has not arrived within 15 working days (21 if abroad), GOV.UK has a tool to check when to expect a reply from HMRC.
Frequently asked questions
What is form SA1?
SA1 is HMRC's postal form to register for Self Assessment if you are not self-employed, for example because you have income from a pension or property, need to pay Capital Gains Tax, or receive income from a trust. GOV.UK points to it when you cannot register online.
What is the deadline to register with SA1?
You must register by 5 October 2026 if you need to send a return for the 2025 to 2026 tax year and have not sent a tax return before. If you tell HMRC after 5 October 2026, you could get a penalty.
Where do I send form SA1?
Print it and post it to HMRC using the postal address shown on the form.
Can I register online instead of using SA1?
Usually, yes. GOV.UK's online registration lets you create sign-in details if you do not have them and save your progress. You cannot register online if you do not live in the UK, which is when the postal SA1 is needed.
How long does it take to get a UTR after sending SA1?
If you register by post, you will usually get your Unique Taxpayer Reference by post in 15 working days (21 days if you are abroad), and it may take longer in busy periods. Online registrations show the UTR in your personal tax account within 72 hours.
I registered before. Do I need SA1 again?
If you have registered before but did not send a tax return last year, GOV.UK says you may need to reactivate your Self Assessment account, and the registration service tells you how.
Is SA1 for the self-employed?
No. SA1 is on GOV.UK's route to register if you are not self-employed. If you are self-employed, choose the self-employed option in GOV.UK's registration service.
