October 9, 2026

Starting a business as a sole trader can be a simple way to work for yourself in the UK. However, if you meet the conditions for Self Assessment, you must register with HM Revenue and Customs (HMRC) and report your income through a tax return. This guide explains how to register for self-assessment as a sole trader, the registration deadline, who needs to register, and what you need to do after registering. What Is Self-Assessment and Why Is It Important? Self Assessment is HMRC’s system for reporting income and calculating the tax you owe. If you are a sole trader in the UK, you usually need to register for Self Assessment if your trading income is more than £1,000 in a tax year. However, other circumstances may also require you to register. Completing your tax return involves reporting your income and allowable expenses to calculate your taxable profit and any tax due. Register when required so you can ensure compliance with HMRC obligations and avoid potential penalties for late registration. Use our Self-Employed Tax Calculator UK to estimate your tax based on your self-employed income and relevant expenses Do I Need to Register for Self Assessment if I’m a Sole Trader? Before discussing how to register for self-assessment as a sole trader, it is crucial to know if you need to register for it. If you are a sole trader, you need to report your income and pay any tax and National Insurance (NI) due. If your gross trading income is more than £1,000 in a tax year, you generally need to register for Self Assessment. This £1,000 test is based on your gross trading income, before deducting business expenses. However, if your trading income is £1,000 or less, you may still need to register for other reasons. For instance, you need to register if you need to show you are self-employed, want to pay voluntary National Insurance contributions (NICs) or need to register for the Construction Industry Scheme (CIS). Additionally, if you need to file a tax return for the 2025/26 tax year and are registering for the first time, you typically need to tell HMRC by 5 October 2026. What Is the Deadline to Register for Self-Assessment as a Sole Trader Another important thing to know before understanding how to register for self-assessment as a sole trader is the deadline to register for self-assessment. Note that the registration deadline depends on the tax year in which you became liable to file a Self Assessment tax return. The UK tax year runs from 6 April to 5 April. If you need to file a Self Assessment tax return for the previous tax year and are registering for the first time, you generally need to tell HMRC by 5 October following the end of that tax year. Example for 2025/26 If you started trading during the 2025/26 tax year (ran from 6 April 2025 to 5 April 2026) and you need to file a Self Assessment tax return, you need to register by 5 October 2026. Your online tax return and any tax owed for 2025/26 are due by 31 January 2027. Remember, you do not have to wait until the deadline to register. You can register earlier, as it gives you more time to receive your UTR and prepare your tax return. How to Register for Self-Assessment as a Sole Trader in the UK HMRC has also introduced an improved Self Assessment registration service to make registration more simple. Here is how you can register for self-assessment: 1. Check Whether You Need to Register Before registering, check if you need to submit a Self Assessment tax return. If you are a sole trader and your gross trading income exceeds £1,000 in a tax year, you need to register. Other circumstances may also mean you need to file a tax return. 2. Have Your National Insurance Number Ready You need a NI number when registering for Self Assessment as a sole trader. If you do not have one, check HMRC’s guidance on applying for one. 3. Register Through HMRC Use the online Self Assessment registration service of HMRC to register as a sole trader. It may ask questions about your circumstances and then guide you through the process. You may need information such as your NI number and the date you started working for yourself. However, the information required can vary depending on your circumstances. 4. Receive Your Unique Taxpayer Reference After registering, HMRC provides your Unique Taxpayer Reference (UTR) to identify you for Self Assessment. 5. Access HMRC Online Services You may need access to HMRC’s online services to manage your Self Assessment obligations and file your tax return. Also, if you are new to HMRC’s online services, follow the setup and sign-in instructions provided during the registration process. What Happens After Registering for Self Assessment? Now that you know how to register for self-assessment as a sole trader, let’s understand what happens after registration. After registering for Self Assessment, HMRC may provide you with a UTR. This UTR identifies you for tax purposes. Your UTR may be available through your online account shortly after registration. Also, it can be sent by post, which can take around 15 days. Then, you need to file a Self Assessment tax return by the relevant deadline if you are required. If your circumstances change and you no longer need to file, you should tell HMRC as well. Do Sole Traders Need to Use Making Tax Digital in 2026/27? Making Tax Digital for Income Tax (MTD for Income Tax) is introduced in stages. From 6 April 2026, sole traders and landlords with qualifying income of more than £50,000 need to follow the MTD rules. If MTD for Income Tax applies to you, you will need compatible software to create, store and correct digital records and send quarterly updates to HMRC. Thus, you will still need to submit an annual tax return and pay any tax due by the relevant deadline Note: The