Updated October 2026: checked against GOV.UK on 17 October 2026.
The SA1 is HMRC's form for registering for Self Assessment if you are not self-employed, such as when you have rental, foreign or investment income to declare. If you live in the UK, you register online; if you don't, you register by post using the paper SA1. The deadline is 5 October after the end of the tax year you need to report (5 October 2027 for 2026/27). If you're starting a business as a sole trader, or joining a partnership, you register through a different route.
SA1 at a glance
- What it is: a registration form, not a tax return. It gets you a Self Assessment record and, if you're new, a 10-digit Unique Taxpayer Reference (UTR).
- Who uses it: individuals who need a tax return for reasons other than self-employment, such as landlords, people with foreign income, investors with untaxed income, and some company directors.
- Who doesn't: sole traders and freelancers (self-employment registration, formerly CWF1) and partners (SA400, SA401, SA402).
- Deadline: 5 October after the tax year ends. For 2025/26 that was 5 October 2026; for 2026/27 it's 5 October 2027.
- UTR: in your personal tax account within 72 hours if you register online. By post, it usually takes 15 working days (21 if you're abroad).
- Online or paper: fill in SA1 online, then submit it, or print and post it if you can't send it online.
How to register for Self Assessment (SA1) online
Most people who aren't self-employed can register online in a few minutes. If you're registering for the first time, follow these steps:
- Check you need a return with HMRC's Check if you need to send a Self Assessment tax return tool.
- Start GOV.UK's Check how to register for Self Assessment service and choose for another reason (not self-employed or a partner), then registering for the first time.
- Sign in with your HMRC sign-in details, or create them. You may be asked to prove your identity with photo ID such as a passport or driving licence.
- Answer the questions and submit, including why you need a return, such as rental, foreign or investment income.
- Find your UTR in your personal tax account. HMRC says it appears within 72 hours of registering online.
Register by 5 October after the end of the tax year (5 October 2027 for 2026/27). You can't register online if you don't live in the UK: fill in form SA1 and post it to HMRC instead. If you've registered before but didn't send a return last year, sign in and reactivate your Self Assessment with your existing UTR rather than registering again.
What does SA1 stand for?
"SA1" is simply HMRC's form number: SA for Self Assessment, 1 for the first form in the series. Its full title is "Register for Self Assessment and get a tax return" if you are not self-employed. It isn't a tax return itself. The return is the SA100, filed after the end of the tax year.
Who should use the SA1 form?
Use SA1 if you need Self Assessment for a reason other than starting a self-employed trade or joining a partnership. Typical cases:
- Landlords. You must tell HMRC if your rental income is more than the £1,000 property allowance. You must file a Self Assessment return if it's more than £2,500 after allowable expenses or £10,000 before expenses. Between £1,000 and £2,500 you can contact HMRC instead of registering.
- Foreign income or gains that haven't been taxed in the UK, including for new arrivals using the 4-year FIG regime, which has to be claimed on a return.
- Savings, dividends or investment income that PAYE can't collect.
- Capital gains that need reporting through a return, and some non-residents with UK income.
- Company directors with untaxed income (dividends, rent from the company and so on). Being a director doesn't, on its own, mean you need a return.
- High Income Child Benefit Charge, only if you can't, or choose not to, pay it through PAYE (see below).
Before registering, use HMRC's "Check if you need to send a Self Assessment tax return" tool. Not every untaxed receipt creates a filing obligation.
SA1 vs CWF1 vs SA400/SA401/SA402: which form do you need?
| Your situation | Registration route | Notes |
|---|---|---|
| Not self-employed, need a tax return (rental, foreign, investment income etc.) | SA1 | Online form; print and post if needed |
| Starting as a sole trader or freelancer | Self-employment registration (formerly form CWF1) | Registers you for Self Assessment and National Insurance together |
| Nominated partner registering a new partnership | SA400 | Registers the partnership |
| Individual joining a partnership | SA401 | One per partner |
| Partner that isn't an individual (such as a company or trust) | SA402 | |
| You already have a UTR but were taken out of Self Assessment | Reactivate your existing record | Don't apply for a second UTR |
| Agent registering a client who isn't self-employed | SA1 via agent services | See HMRC's agent registration guidance |
SA1 online, PDF or paper?
People search for an "SA1 form PDF", but HMRC no longer offers a downloadable blank form. The current process is:
- Fill in SA1 online on GOV.UK. You can save your progress and come back later to finish registering.
- Submit it online, or, if you can't send it online, print the completed form and post it to the address shown on it.
You'll need:
- your full name;
- your postal address;
- your date of birth;
- a daytime telephone number;
- your UK National Insurance number, if you have one.
No National Insurance number? HMRC normally needs a valid NINO to set up the record. There are exceptions for some people who won't have one, such as certain foreign nationals and non-residents. If you're eligible for a NINO, apply for one first, then register.
What is the SA1 deadline?
You must tell HMRC by 5 October following the end of the tax year in which you first need to file:
| Tax year | Tax year ended | Register by | Paper return by | Online return and payment by |
|---|---|---|---|---|
| 2025/26 | 5 April 2026 | 5 October 2026 | 31 October 2026 | 31 January 2027 |
| 2026/27 | 5 April 2027 | 5 October 2027 | 31 October 2027 | 31 January 2028 |
The same deadline applies if you registered before but didn't need to send a return for the previous year.
Missed 5 October 2026?
Register now. Don't wait until January. HMRC can charge a failure-to-notify penalty if late registration means tax is paid late. Registering promptly, then filing online and paying by 31 January 2027, keeps your exposure as low as possible. For returns that are late in their own right, GOV.UK lists:
- an initial £100 penalty;
- after 3 months, £10 a day up to £900;
- after 6 months, a further 5% of the tax due or £300, whichever is greater (repeated at 12 months).
When will I get my UTR?
If you registered online, your UTR will be in your personal tax account within 72 hours. If you don't already have a personal tax account, you'll get one as part of registering. If you registered by post, HMRC says you'll usually get your UTR by post in 15 working days (21 if you're abroad), but it can take longer during busy periods. If you've heard nothing after about three weeks, use HMRC's "check when you can expect a reply" tool before chasing.
Your UTR is the 10-digit number you'll use to file your return, to pay (UTR + K: see our guide to paying HMRC) and as your UK Tax Identification Number on overseas and bank forms (see What is your UK TIN?).
High Income Child Benefit Charge: you may not need SA1
The HICBC applies where you or your partner have adjusted net income over £60,000 (from 2024/25). It claws back 1% of Child Benefit for every £200 over £60,000, so all of it is repaid at £80,000. Employees who don't need a return for any other reason can now pay the charge through PAYE instead of registering for Self Assessment. Check HMRC's HICBC guidance before using SA1 just for this.
Landlords: Making Tax Digital is coming
If you're registering because of rental income, plan ahead for Making Tax Digital for Income Tax, which applies to sole traders and landlords according to their qualifying income (gross self-employment plus property income):
| Qualifying income in… | Threshold | MTD for Income Tax from |
|---|---|---|
| 2024/25 | over £50,000 | 6 April 2026 |
| 2025/26 | over £30,000 | 6 April 2027 |
| 2026/27 | over £20,000 | 6 April 2028 |
After you register
- Keep your UTR safe and set up your Government Gateway / HMRC online account to file online.
- File your return by 31 January (online) and pay any tax due. You may also have to make payments on account for the following year.
- If your circumstances change and you no longer need a return, tell HMRC. See how to notify HMRC that you no longer need to file.
FAQ
What is an SA1 form?
The HMRC form used to register for Self Assessment if you're not self-employed. It creates your Self Assessment record and issues a UTR if you don't already have one.
What is the SA1 full form?
SA stands for Self Assessment. The form's full name is "Register for Self Assessment and get a tax return" (if you're not self-employed).
Can I download an SA1 form as a PDF?
Not as a blank form. HMRC's SA1 is filled in online. If you can't submit it online, you print the completed form and post it to HMRC.
Is the SA1 the same as a tax return?
No. SA1 is the registration. The tax return (SA100) is filed after the tax year ends, by 31 October on paper or 31 January online.
Do I need SA1 if I'm a company director?
Not automatically. You need it only if you have income that must be reported through Self Assessment, such as dividends or other untaxed income, and you aren't already registered.
I'm self-employed. Should I use SA1?
No. Register as self-employed instead (formerly form CWF1), which also sets up your National Insurance. SA1 is for people who aren't self-employed.
I already have a UTR from years ago. Do I need SA1 again?
No. Reactivate your existing Self Assessment record rather than applying for a second UTR.
Can I register with SA1 if I live abroad?
Yes, but only by post. You can't register online if you don't live in the UK, so fill in the paper SA1 with your overseas address and post it to HMRC. Allow longer for your UTR to arrive by post. Non-residents with UK rental income should also read our guide to UK taxation of non-residents.
What happens if I register after 5 October?
You may face a failure-to-notify penalty if tax ends up paid late. Register as soon as possible, then file and pay by 31 January to keep any penalty to a minimum.
Related guides
- Paying HMRC: Shipley vs Cumbernauld bank details and references
- What is your UK TIN (UTR) if you are a UK tax resident?
- How to tell HMRC you no longer need to file a Self Assessment return
- I make no money: do I still need to file a tax return?
- Crypto-assets in the UK: when is a tax return due?
- 60-day Capital Gains Tax reporting on UK property
- The UK's Foreign Income and Gains (FIG) regime: ultimate guide
- Missed the tax deadline?
- Add once published: Self Assessment deadline 31 January 2027 (planned post N4)
General information only, not advice for your circumstances. Checked against GOV.UK on 17 October 2026.
