How to Register for Self Assessment: HMRC Online Guide

Registering for Self Assessment is the first step to reporting your income to HMRC as a self-employed person, landlord, or anyone with untaxed income. The registration process is done online and typically takes around 15 minutes — but your Unique Taxpayer Reference (UTR) arrives by post, so you need to allow time before your filing deadline.

This guide walks through the full registration process, from checking whether you need to register to setting up your HMRC online account.

Who Needs to Register for Self Assessment?

You need to register for Self Assessment if any of the following apply to your tax situation:

You're self-employed with trading income over £1,000 per tax year (the trading allowance, unchanged for 2025/26)
You earn rental income over £1,000 per tax year (the property allowance, unchanged for 2025/26)
You have untaxed income (savings interest above your allowance, dividends, foreign income)
You're a company director with untaxed income, such as dividends — being a director on its own doesn't require a return
You received capital gains above the annual exempt amount (£3,000 in 2025/26)
You need to pay the High Income Child Benefit Charge (income over £60,000 in 2025/26) and don't pay it through PAYE

Note: Earning over £100,000 no longer triggers Self Assessment by itself. HMRC removed the income-only criterion for PAYE taxpayers from the 2024/25 tax year onwards — if all your income is taxed through PAYE and none of the points above apply, you generally don't need a return.

If you're unsure, use HMRC's free Check if you need to send a Self Assessment tax return tool. It takes about 5 minutes and covers all income types.

For more detail on whether self-employment triggers registration, see our guide on whether you need to register as self-employed.

Self Assessment Registration Deadlines

You need to register by 5 October following the end of the tax year in which you first need to file.

When your income started	Tax year	Registration deadline
Between 6 April 2024 and 5 April 2025	2024/25	5 October 2025
Between 6 April 2025 and 5 April 2026	2025/26	5 October 2026
Between 6 April 2026 and 5 April 2027	2026/27	5 October 2027

Example: Sarah starts freelancing in September 2025. Her first tax year with self-employment income is 2025/26. She needs to register for Self Assessment by 5 October 2026.

If you miss the deadline, HMRC may charge a penalty — even if you don't owe any tax. Registering late is better than not registering at all.

What You Need to Register for Self Assessment

Have the following ready before you start the online registration:

National Insurance number — on your payslip, P60, or HMRC letters
Personal details — full name, date of birth, current address
Business details (if self-employed):
- The date you started trading
- Your business name (or your own name if you trade as yourself)
- Your business address
- The nature of your business (e.g., "plumbing", "graphic design", "consultancy")
Email address and phone number — HMRC uses these for account security

How to Register for Self Assessment Online

To register for Self Assessment online, follow these four steps:

Create a Government Gateway account at GOV.UK
Complete the Self Assessment registration form for your situation
Receive your UTR by post, usually around 15 days later
Set up your HMRC online account to file returns

Each step is covered in detail below.

Step 1: Create a Government Gateway Account

Government Gateway is the login system for HMRC online services. If you don't already have one, you'll need to create it.

Go to HMRC online services
Select "Create sign in details" — you can create either a Government Gateway or GOV.UK One Login account
Enter your email address and create a password
If using Government Gateway, you'll receive a User ID (up to 12 characters) — save this somewhere safe
Complete any identity verification steps (you may need photo ID)

If you already have a Government Gateway or GOV.UK One Login account from another government service, you can use the same one for Self Assessment.

Tip: Write down your User ID and password. You'll need these every time you log in to manage your tax affairs or file a return.

Step 2: Register for Self Assessment

The registration route depends on your situation:

If you're self-employed (sole trader):

Go to Register for Self Assessment on GOV.UK
Sign in with your Government Gateway credentials
Select that you're registering as self-employed
Enter your personal details and National Insurance number
Provide your business details (name, address, start date, type of work)
Submit your registration

If you're a landlord or have other untaxed income (not self-employed):

Go to Register for Self Assessment on GOV.UK
Sign in with your Government Gateway credentials
Select the relevant reason for registering (rental income, untaxed income, etc.)
Enter your personal details
Submit your registration

If you're in a partnership: The nominated partner registers the partnership separately, and each partner also registers individually for Self Assessment.

Step 3: Receive Your UTR

After registering, HMRC sends your Unique Taxpayer Reference (UTR) by post. This is a 10-digit number that identifies you for Self Assessment purposes.

Expected delivery: Around 15 days (UK addresses)
Overseas addresses: Takes longer — allow extra time

You need your UTR to file your tax return, so register well ahead of any deadlines.

If you've registered before: If you previously had a UTR but stopped filing, your old UTR may still be active. Check any previous HMRC correspondence or call HMRC to confirm before re-registering.

Step 4: Set Up Your Online Account

Once you have your UTR, you can access your full Self Assessment account online:

Log in at HMRC online services with your Government Gateway credentials
You may need to enter your UTR to link it to your online account
You may receive a separate Activation Code by post — enter this when prompted to complete the setup

After activation, you can:

File your tax return online
View your tax calculation and payments due
Make payments or set up Direct Debit
Manage your personal details

What Is a UTR and Why Does It Matter?

A Unique Taxpayer Reference (UTR) is your personal identifier for Self Assessment. It's a 10-digit number that stays with you for life — even if you stop filing returns and come back to Self Assessment years later.

You'll need your UTR to:

File your Self Assessment tax return
Communicate with HMRC about your tax
Sign up for Making Tax Digital for Income Tax (mandatory from April 2026 for qualifying income over £50,000; from April 2027 for income over £30,000)
Provide to clients or contractors who request it (common in the construction industry under CIS)

Where to find your UTR:

The registration letter HMRC sends after you register
Previous tax returns or HMRC correspondence
Your HMRC online account (once set up)
The HMRC app

For more on how the number works and what to do if you lose it, see our guide on what a UTR number is.

Self Assessment Registration and Making Tax Digital

Since 6 April 2026, Making Tax Digital (MTD) for Income Tax is mandatory for self-employed people and landlords with qualifying income over £50,000 in the 2024/25 tax year. From April 2027, this extends to those with income over £30,000, and from April 2028 to income over £20,000. MTD sign-up is separate from Self Assessment registration, but you need to be registered for Self Assessment first.

If your income exceeds the MTD threshold:

Register for Self Assessment (this guide)
Sign up for MTD through your HMRC online account
Use compatible software to keep digital records and send quarterly updates

See our Making Tax Digital guide for the full MTD sign-up process and software requirements.

What Happens After Self Assessment Registration

Once registered, HMRC expects you to file a tax return every year until you tell them otherwise. Here's what to expect:

What	When
UTR arrives by post	Around 15 days after registering
First tax return becomes available online	After 6 April following the end of the tax year
Paper filing deadline	31 October following the end of the tax year
Online filing deadline	31 January following the end of the tax year
Payment deadline	31 January following the end of the tax year

Example: James registers in November 2025 for the 2025/26 tax year. His tax return for 2025/26 becomes available from 6 April 2026, and he needs to file online and pay by 31 January 2027.

When you're ready to submit, our guide on filing your first tax return walks through the process step by step.

If you no longer need to file (for example, you stopped self-employment and have no other untaxed income), you can ask HMRC to remove you from Self Assessment. You can do this online or by phone. It's important to formally notify HMRC rather than simply stopping filing, as missing returns may result in penalties.

Frequently Asked Questions

How long does it take to register for Self Assessment?

The online form takes around 15 minutes to complete. However, your UTR arrives by post around 15 days after you register, so the full process from registration to being ready to file takes around three weeks. Register well before you need to submit your return.

Can I file a Self Assessment tax return without a UTR?

No. You need your UTR to file a Self Assessment return, whether online or on paper. If you're close to a deadline and haven't received your UTR, contact HMRC to check the status of your registration.

Do I need to register again each year?

No. Once registered, your Self Assessment record stays active until you tell HMRC you no longer need to file. You use the same UTR and Government Gateway login each year.

Is Self Assessment registration the same as registering a business?

Registering for Self Assessment tells HMRC you have income to report. It's separate from registering a company with Companies House, registering for VAT, or getting business insurance. As a sole trader, you don't need to register a company — Self Assessment registration is sufficient.

What if I registered before but stopped filing?

Your UTR may still be active. Log in to your HMRC online account or call HMRC to check. If your record is dormant, HMRC can reactivate it without issuing a new UTR.

Can I register for Self Assessment by phone or post?

Online registration is the standard method. If you're unable to register online (for accessibility reasons, for instance), you can call HMRC's Self Assessment helpline on 0300 200 3310 for assistance.

This guide is for informational purposes only and does not constitute tax, legal, or financial advice. Tax rules change frequently. Always verify current requirements on GOV.UK or consult a qualified accountant for your specific situation.

Official Sources

Register for Self Assessment - GOV.UK
Check if you need to send a Self Assessment tax return - GOV.UK
HMRC online services: sign in or set up an account - GOV.UK
Working for yourself - GOV.UK
Self Assessment tax returns - GOV.UK