How to Register for Self Assessment

If you receive income that is not fully taxed through PAYE, you may need to register for Self Assessment with HMRC. Registering within the required deadline is important to avoid potential penalties.

For the 2025/26 tax year, which ran from 6 April 2025 to 5 April 2026, you generally need to tell HMRC by 5 October 2026 if you need to file a Self Assessment tax return and have not filed one before.

This blog explains who needs to register, what information you need, how to register online, what happens after registration and the key deadlines to remember.

What Is Self Assessment?

Self Assessment is a system HM Revenue and Customs (HMRC) uses to collect Income Tax. If you are required to complete a Self Assessment tax return, you must report your income and certain gains, claim relevant reliefs and allowances, and work out the tax you owe.

You use a Self Assessment tax return to report income and other taxable amounts, such as:

• Self-employment income
• Rental income
• Dividends
• Savings interest
• Foreign income
• Capital gains
• Certain pension income
• Other untaxed income

HMRC uses the information in your tax return to work out how much tax you owe. 

Not everyone who receives additional income needs to register. The requirement depends on your circumstances and the type and amount of income you receive.

Who Needs to Register for Self Assessment?

You may need to register for Self Assessment if you:

• Are a sole trader whose gross trading income exceeds £1,000 in a tax year
• Are a partner in a business partnership
• Have taxable rental income
• Have certain untaxed foreign income
• Have Capital Gains Tax to pay
• Need to pay the High Income Child Benefit Charge and do not pay it through PAYE
• Receive certain untaxed savings or dividend income
• Have other income that cannot be collected through your PAYE tax code

For example, if you start freelancing alongside your employment and your gross trading income exceeds £1,000 during a tax year, you may need to register for Self Assessment.

When Do You Need to Register for Self Assessment?

The general registration deadline is 5 October following the end of the tax year in which you first had income that needs to be reported.

For example:

If you need to register for the 2025/26 tax year, the deadline is 5 October 2026.

Registering after the applicable deadline may result in a penalty. It is therefore important to register once you establish that you need to file a Self Assessment tax return.

How to Register for Self Assessment Online

Registering for Self Assessment online is usually straightforward. However, the steps you need to follow depend on why you need to submit a tax return. Before registering, check whether you need to complete a Self Assessment tax return.

Step 1: Check Whether You Need to Register

Before starting your registration, check whether you need to file a Self Assessment tax return with HMRC.

You may need to register if you are self-employed, receive rental income, have certain untaxed income or need to report other income that is not fully taxed through PAYE.

Step 2: Sign In to Your HMRC Online Account

You need a Government Gateway account to access most HMRC online services.

Your Government Gateway account allows you to access your HMRC tax services, manage your Self Assessment account and submit your tax return online.

Step 3: Choose the Correct Registration Type

The registration process depends on your circumstances.

Registering as a Sole Trader

If your total trading income is more than £1,000 in a tax year, you need to register, although different rules can apply in some circumstances.

You will need to provide details about yourself and your business, including when you started working for yourself and the type of work you do.

Registering for Other Reasons

You may need to register for Self Assessment even if you do not run a business.

For example, registration may be required if you have certain:

• Rental income
• Foreign income
• Investment income
• Capital Gains Tax obligations
• High Income Child Benefit Charge obligations
• Other income that needs to be reported to HMRC

In these circumstances, HMRC’s registration service will guide you to the appropriate registration route. 

Step 4: Complete the Registration Form

Once you have selected the appropriate registration route, provide the required information.

Depending on your circumstances, this may include:

• Full name and date of birth
• National Insurance number
• Home address
• Contact details
• Business details, if you are self-employed
• Date you started trading
• Type of work or business activity
• Reason for completing a Self Assessment tax return
• Date the relevant income started

Ensure that all information is accurate and up to date. Review your details carefully before submitting the registration.

Step 5: Submit Your Registration

After completing the registration form, review the information provided and submit it to HMRC.

Keep a record of your registration and any confirmation you receive.

If you register as self-employed, HMRC will set up your Self Assessment record and send you a Unique Taxpayer Reference (UTR). You will need this number when dealing with your Self Assessment tax return.

If you need to register for Self Assessment, you should use HMRC’s online registration service through your Personal Tax Account. In some cases, different registration routes or forms may apply.

What Information Do You Need to Register?

Preparing the required information in advance can help you complete the registration accurately. 

If You Are Self-Employed

You will generally need:

• Full name
• Previous name, if applicable
• Date of birth
• National Insurance number
• Home address
• Telephone number
• Email address
• Business name, if applicable
• Business address, if different from your home address 
• Date you started working for yourself
• Description of your business or work
• Reason for registering

HMRC requires a National Insurance number when registering as a sole trader.

If You Are Not Self-Employed

If you need to register for another reason, such as rental income or certain untaxed income, HMRC may ask for:

• Full name
• Date of birth
• National Insurance number, if you have one
• Address
• Contact details
• Reason for registering
• Date the relevant income started

Individual customers who need to register for Self Assessment can now use HMRC’s online registration service through their Personal Tax Account. Form SA1 may still be used by agents to register clients who are not self-employed.

How to Register for Self Assessment If You Are Self-Employed

If you are starting work as a freelancer, contractor or sole trader, you need to register as a sole trader with HMRC.

The registration process involves:

1. Checking whether you need to register.
2. Gathering your National Insurance number and personal details.
3. Creating or signing in to your Government Gateway account.
4. Registering as a sole trader through HMRC.
5. Providing your business and start-date information.
6. Submitting your registration.
7. Receiving and keeping your UTR.
8. Keeping accurate income and expense records.
9. Completing your Self Assessment tax return by the relevant deadline.

You can start trading as a sole trader before registering, but you must register for Self Assessment if your gross trading income exceeds £1,000 in a tax year.

How to Register for Self Assessment as a Company Director

Being a director of a limited company does not automatically mean that you must register for Self Assessment.

If your income consists only of a director's salary taxed through PAYE and there is no other income that needs to be reported, you may not need to file a Self Assessment tax return.

However, you may need to register if you receive income that needs to be reported separately, such as certain dividends, benefits or other untaxed income.

Your personal UTR is different from your company's UTR. Make sure you use the correct reference when dealing with HMRC.

Can You Register for Self Assessment by Post?

Yes. Some people may need to use the postal registration process where their circumstances are not covered by the standard online registration route.

For individuals who are not self-employed but need to register for Self Assessment, HMRC’s online registration service through your Personal Tax Account is the main route.

Most individual customers can register for Self Assessment online through HMRC’s Personal Tax Account.

Conclusion

Registering for Self Assessment is an important step if you have income that needs to be reported to HMRC. The registration process involves checking whether you need to file a tax return, selecting the appropriate registration route, providing your details and receiving your UTR.

For the 2025/26 tax year, the registration deadline is 5 October 2026, while the online tax return and payment deadline is 31 January 2027.

Keeping accurate records and meeting the relevant registration and filing deadlines can help you manage your Self Assessment responsibilities and avoid potential penalties.

Need help with Self Assessment?

Speedia provides Self Assessment tax return, bookkeeping and year-end accounts support for UK individuals and sole traders. 

Frequently Asked Questions

1. When should I register for Self Assessment with HMRC?

You should usually register by 5 October after the end of the tax year in which you first need to file a tax return.

2. How do I register for Self Assessment and get a UTR?

Register through HMRC online by providing your details. HMRC will then set up your account and issue a 10-digit UTR number.

3. Can I register for Self Assessment through my Personal Tax Account? 

Yes. Most individual customers can register for Self Assessment through HMRC’s online service in their Personal Tax Account. You can sign in using your Government Gateway details or GOV.UK One Login, depending on your account.

4. How do I register myself as self-employed with HMRC?

You can register online with HMRC as a sole trader by providing your personal details, National Insurance number and business information.

5. How do I register for Self Assessment for the first time?

First, check whether you need to file a Self Assessment tax return. If you do, register through HMRC’s online service using your Personal Tax Account. You can create or access your account using Government Gateway or GOV.UK One Login, depending on your HMRC sign-in details.

6. What form do I need to register for Self Assessment?

You do not usually need to choose a form yourself. Use HMRC’s online registration service, which will guide you through the correct process based on your circumstances. If you are self-employed, you can register through the same service.

7. How long does it take to register for Self Assessment?

HMRC’s new online registration service issues your Unique Taxpayer Reference (UTR) in your online account within 72 hours after you complete your registration. This is faster than the previous process, where a UTR could take up to 15 days to arrive by post.