Filing a self-assessment return is a crucial responsibility for many taxpayers in the UK, and understanding when you need to complete one can save you from penalties and stress. Whether you are self-employed, receive rental income, or have other sources of income, knowing the triggers to file a self-assessment tax return is essential. If this is your first time, remember to register with HMRC by 5 October following the end of the tax year to comply with regulations. This guide will help clarify who must send in a tax return and provide tips to make the process smoother.
Who Must Send in a Tax Return: Key Triggers and Conditions
There are a number of reasons why you might need to complete a self-assessment tax return, and these triggers vary based on your financial activities throughout the year. Here are the most common scenarios requiring the submission of a self-assessment:
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Self-Employment: If you were self-employed as a sole trader and earned more than £1,000 (before expenses) during the tax year, you must file a tax return. This applies even if you receive other types of income or no PAYE salary.
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Business Partnerships: Being a partner in a business partnership also requires submitting a self-assessment tax return regardless of the level of income.
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High Income Threshold: If your total taxable income exceeded £150,000 in the 2025–26 tax year, you must file a self-assessment. This includes all earnings combined from employment, self-employment, investments, and property.
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Rental Income and Capital Gains: Even if your income is under the £150,000 threshold, having income from property rentals or capital gains tax liabilities means you need to complete a return.
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Other Untaxed Income: Income such as tips, commission, dividends, foreign income, or savings interest not taxed at source also triggers the requirement to send in a tax return.
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Company Directors: Company directors usually must file a tax return except for those directors of non-profit organisations.
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High Income Child Benefit Charge: If you or your partner earned over £50,000 and received child benefit, you might be liable for this charge and need to declare it via self-assessment.
Register with HMRC by 5 October If You’re Filing for the First Time
If you’ve never filed a self-assessment tax return before and find that you meet any of the above conditions, it’s important to register with HMRC by the deadline to avoid penalties. For the 2025–26 tax year, which runs until 5 April 2026, the deadline to register online is 5 October 2026.
Registration is simple and can be done online through the official government portal. Once registered, HMRC will provide you with a Unique Taxpayer Reference (UTR) number allowing you to file your return by the submission deadline.
How Simply Accounts Accountant Chester Can Help
Understanding who must send in a tax return and the complexities of self-assessment can be challenging, particularly if you have multiple income sources or are newly self-employed. A professional accountancy firm like Simply Accounts Accountant Chester can provide invaluable assistance.
From guidance on whether you need to file, help with registering, to managing your tax returns accurately and on time, their expertise ensures you remain compliant and optimise your tax position. They can also assist with:
- Advising on allowable expenses and deductions.
- Navigating capital gains and rental income reporting.
- Meeting filing deadlines and avoiding penalties.
This can save you time and stress while maximising your financial efficiency.
Use HMRC’s Online Tool to Check Your Requirement
If you’re unsure whether you must send in a tax return, HMRC provides an excellent online tool to help you decide. By answering a few straightforward questions, you can quickly establish your filing obligations for the tax year.
Visit: www.gov.uk/check-if-you-need-tax-return/ to access the tool and determine if you should register.
Filing a self-assessment return is a legal requirement for many people with varying income types, from self-employment to rental income and beyond. Knowing the triggers for filing and acting promptly—especially for first-time filers who must register by 5 October after the tax year ends—is essential to avoid unnecessary fines.
Whether your taxable income exceeds £150,000, you have income from savings, investments, or property, or you are a company director, understanding who must send in a tax return empowers you to stay compliant. If you're unsure, utilise HMRC’s online tool or seek advice from professionals like Simply Accounts, Accountant Chester, Accountant Birchwood, Accountant Netherton, Accountant Orrell Park, Accountant Everton, to navigate the process easily.
Taking the time to understand your obligations now will make managing your taxes much simpler and more efficient, allowing you to focus on growing your business or investment income with peace of mind.