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
• You earn rental income over £1,000 per tax year
• You have untaxed income (savings interest above your allowance, dividends, foreign income)
• You're a company director (unless for a non-profit with no pay or benefits)
• You received capital gains above the annual exempt amount
• You earn over £150,000 from any source (2025/26)
• You need to pay the High Income Child Benefit Charge (income over £60,000 in 2025/26)

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

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

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.

1. Go to HMRC online services
2. Select "Create sign in details"
3. Enter your email address and create a password
4. You'll receive a User ID (up to 12 characters) — save this somewhere safe
5. Complete any identity verification steps

If you already have a Government Gateway 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):

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

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

1. Go to Register for Self Assessment on GOV.UK
2. Sign in with your Government Gateway credentials
3. Select the relevant reason for registering (rental income, untaxed income, etc.)
4. Enter your personal details
5. 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: Within 10 working days (UK addresses)
• Overseas addresses: May take up to 21 working days

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:

1. Log in at HMRC online services with your Government Gateway credentials
2. You may need to enter your UTR to link it to your online account
3. 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
• Register for Making Tax Digital (from April 2026 for qualifying income over £50,000)
• 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

Self Assessment Registration and Making Tax Digital

From 6 April 2026, self-employed people and landlords with qualifying income over £50,000 need to use Making Tax Digital (MTD) for Income Tax. 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:

1. Register for Self Assessment (this guide)
2. File at least one Self Assessment return
3. Then sign up for MTD through your HMRC online account

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

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	Within 10 working days of registering
First tax return becomes available online	After 6 April 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.

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 within 10 working days, so the full process from registration to being ready to file takes 2-3 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.

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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