How to Register for Self Assessment

If you need to complete a Self Assessment tax return, you must first register with HMRC. When you register, you'll receive a 10-digit Unique Taxpayer Reference (UTR) number which you'll use to file your returns. The registration process depends on your circumstances, and there are specific deadlines you need to meet to avoid penalties.

Who needs to register for Self Assessment

You must register for Self Assessment if, in the last tax year (6 April to 5 April), any of the following applied:

• You were self-employed as a sole trader and earned more than £1,000 (before taking off anything you can claim tax relief on)
• You were a partner in a business partnership
• You had to pay Capital Gains Tax when you sold or disposed of something that increased in value
• You had to pay the High Income Child Benefit Charge and do not pay it through PAYE
• You are an off-payroll worker who is repaying a student or postgraduate loan

You may also need to register if you have untaxed income such as:

• Money from renting out a property
• Tips and commission
• Income from savings, investments and dividends
• Foreign income

You can also choose to fill in a tax return to claim certain Income Tax reliefs, prove you're self-employed (for example to claim Tax-Free Childcare or Maternity Allowance), or pay voluntary National Insurance contributions.

Registration deadlines

You must tell HMRC by 5 October if you need to complete a tax return for the previous year and you have either:

• Not sent a tax return before
• Registered before but did not need to send a tax return for the tax year 2023 to 2024

You can tell HMRC by registering for Self Assessment. You could be fined if you do not tell HMRC by 5 October.

How to register if you're self-employed

If you're self-employed, you'll need to follow a specific registration process. This is different from registering for other reasons such as rental income or Capital Gains Tax.

How to register if you're not self-employed

If you need to register for Self Assessment but you're not self-employed, you must complete form SA1. You would use this form if you, for example:

• Receive income from land and property in the UK
• Have taxable foreign income
• Need to pay the High Income Child Benefit Charge and have not chosen to pay it through PAYE
• Receive yearly income from a trust or settlement
• Get untaxed income that cannot be collected through your PAYE tax code
• Have Capital Gains Tax to pay

What information you'll need

Before you start, gather all your information together. You'll fill in the form online and you cannot save your progress.

You'll need to provide your:

• Full name
• Postal address (this can be outside the UK)
• Date of birth
• Daytime telephone number
• UK National Insurance number, if you have one

You'll also need to explain why you need to register for Self Assessment and the date this started.

Submitting form SA1

You can either fill in the form online or print and post it.

To fill it in online, you'll need to either sign in to use the service (you can create sign-in details if you don't have them), or use your email address to get a confirmation code to sign in.

Alternatively, you can download form SA1, print it, and post it to HMRC using the postal address shown on the form.

If you've previously registered

If you did not send a tax return last year, you should check how to register as you may need to reactivate your Self Assessment account.

Checking how to register will make sure you submit your return in the right way and mean your return is processed more quickly and any refunds or correspondence from HMRC are not delayed.

Your tax return may be delayed if you file it without reactivating an existing account.

Understanding your Unique Taxpayer Reference (UTR)

A Unique Taxpayer Reference is a 10-digit number. It might just be called 'tax reference'. You get a UTR when you register for Self Assessment or set up a limited company.

When you'll receive your UTR

You'll usually get your UTR by post around 15 days after you register. It takes longer if you live overseas.

If you registered online, you may be able to get your UTR sooner using the HMRC app or your personal tax account.

HMRC will usually contact you within 21 days of receiving your form but may take longer during busy periods. If HMRC has not contacted you after 3 weeks, you can check when you can expect a reply.

Where to find your UTR later

If you're an individual or sole trader, you can find your UTR:

• In your Personal Tax Account
• In the HMRC app
• On previous tax returns and other documents from HMRC (for example, notices to file a return or payment reminders)

If you cannot find your UTR on any documents or online, contact HMRC.

If you have a limited company, you can request your Corporation Tax UTR online. HMRC will send it to the business address registered with Companies House.

After you register

Once you've registered and received your UTR, you should start preparing for your tax obligations:

• Keep records such as bank statements and receipts so you can fill in your tax return correctly
• Estimate how much tax you might need to pay
• Consider setting up monthly or weekly payments to help you budget for your bill
• Send your tax return any time after 5 April – doing it earlier means you'll know what you owe

You'll need to pay your tax bill by 31 January.

If you don't think you can pay on time, you can set up a payment plan once you know what you owe.

Sources

• Find your UTR number
• Register for Self Assessment if you are not self-employed
• Self Assessment tax returns

This article provides general guidance based on current HMRC rules. For advice specific to your situation, speak to your accountant.