How to Register for Self Assessment with HMRC

If you earn income outside of PAYE – whether through self-employment, property rentals, freelance work, or investments – you may be required to file a Self Assessment tax return. But before you can file, you must first register with HMRC (His Majesty’s Revenue and Customs). This guide walks you through the full registration process, deadlines, and what to expect afterward.

What is Self Assessment?

Self Assessment is the system used by HMRC to collect Income Tax from individuals and businesses whose earnings are not automatically taxed. This includes sole traders, landlords, and anyone with untaxed income.

For a general overview, visit Wikipedia’s page on Self-assessment (tax).

Who Needs to Register for Self Assessment?

You must register for Self Assessment if any of the following applies:

• You’re self-employed or a sole trader and earned more than £1,000 in a tax year
• You’re a partner in a business partnership
• You earn income from property rental
• You earn foreign income
• You receive dividends or other investment income
• You have capital gains
• You receive income from tips and commissions

You’re a director of a limited company (with untaxed income)

Even if you're not sure, it's better to check your eligibility than risk a penalty for not registering. You can always seek help at Self Assessment Tax Return for expert advice and services.

When to Register

• The deadline to register for Self Assessment is:
• 5 October following the end of the tax year in which you earned untaxed income.

For example:

If you started self-employment in July 2024 (during the 2024/25 tax year), you must register by 5 October 2025.

Failing to register by this date could result in penalties and interest charges, even if you file later.

How to Register for Self Assessment with HMRC

The registration process depends on your circumstances. Here’s a step-by-step guide:

1. Create a Government Gateway Account

Before you can access HMRC services, you need a Government Gateway user ID and password. You’ll use this to manage your tax account online.

To create one:

• Go to www.gov.uk
• Click “Register” under HMRC services
• Provide your name, email address, and a password
• Verify your identity as required

2. Register for the Correct Service

You must now register for Self Assessment using the right form based on your role:

If You’re Self-Employed

Complete the CWF1 form:

• Log into your Government Gateway
• Choose “Register for Self Assessment and Class 2 National Insurance”
• Provide details about your business, such as the trading name, start date, and nature of the business

If You’re Not Self-Employed but Need to File

Use the SA1 form if you:

• Receive untaxed income
• Are a company director

Have income from savings or investments

• Earn rental income
• You can register online or by post.
• If You’re in a Business Partnership

Use the SA401 form (for individual partners) and SA400 (to register the partnership itself).

3. Wait for Your UTR Number

After registration, HMRC will issue your Unique Taxpayer Reference (UTR) number. This 10-digit code is essential for filing tax returns.

• You’ll receive it by post within:
• 10 working days (UK residents)
• 21 working days (if you're abroad)

Keep this number secure – you'll need it each year when you file your return.

4. Activate Your Online Account

Shortly after receiving your UTR, HMRC will send an activation code for your online tax account. This code lets you access the Self Assessment portal.

Use this code within 28 days (or request a new one)

Once activated, you can view your tax obligations, file returns, and make payments online

What Happens After You Register?

Once you're registered:

• You must file your tax return each year (by 31 January following the end of the tax year)
• You’ll be responsible for paying any Income Tax, Class 2 and 4 National Insurance, and possibly Capital Gains Tax
• You may also need to make payments on account, depending on your tax bill
• If you're unsure how to proceed or want to avoid errors, it’s wise to work with a tax professional. The experts at Self Assessment Tax Return can help you file accurately and on time.

| Action | Deadline |

| ---------------------------- | ---------- |

| Register for Self Assessment | 5 October |

| File paper tax return | 31 October |

| File online tax return | 31 January |

| Pay your tax bill | 31 January |

| Payments on account (1st) | 31 January |

| Payments on account (2nd) | 31 July |

Common Registration Mistakes to Avoid

• Waiting too long to register
• Using the wrong registration form
• Losing your UTR or not activating your account
• Assuming you're automatically registered if previously employed
• Not updating HMRC when your income changes

Need Help?

Registering for Self Assessment can be straightforward, but mistakes can be costly. If you want expert support or don’t have time to manage it all yourself, the team at Self Assessment Tax Return can handle registration, filing, and compliance for you.

Final Thoughts

Registering for Self Assessment with HMRC is a necessary first step to staying compliant if you earn untaxed income. By understanding the deadlines and following the proper process, you can avoid penalties and keep your finances in order. Don’t wait until it’s too late—start your registration today and get ahead of your tax responsibilities.