Who Needs to File a Self-Assessment Tax Return in the UK

Filing a self-assessment tax return can feel confusing if you are unsure whether HMRC requires you to do so. The self-assessment system exists to make sure everyone pays the right amount of tax on income that is not taxed at source. This includes income from self-employment, property, investments, and overseas sources. Understanding who must file a return helps avoid penalties and ensures compliance with UK tax laws.

What Is Self-Assessment and Why Does It Matter?

Self-assessment is a system introduced by HM Revenue & Customs (HMRC) to collect income tax, National Insurance contributions, and capital gains tax (CGT) from individuals whose income is not fully taxed through PAYE (Pay As You Earn). It targets people with income sources that HMRC cannot automatically track or tax.

The system requires individuals to report their income, claim any reliefs or allowances, and calculate the tax they owe. Filing a return on time helps avoid fines and interest charges. It also allows taxpayers to claim refunds if they have paid too much tax.

Who Must File a Self-Assessment Tax Return?

HMRC sets specific criteria for who must complete a self-assessment tax return. Below are the main groups required to file:

Self-Employed Individuals Earning More Than £1,000

If you run your own business or work as a freelancer and earn more than £1,000 in a tax year, you must file a return. This includes sole traders and those with side businesses.

For example, a graphic designer earning £1,200 from freelance projects alongside a salaried job must complete a self-assessment.

Partners in a Business Partnership

If you share ownership of a business partnership, each partner must file a tax return to report their share of profits.

Landlords Receiving Rental Income

Anyone earning income from letting property must declare this through self-assessment. This applies even if the property is rented out occasionally or through platforms like Airbnb.

For instance, a homeowner renting out a spare room or a buy-to-let landlord must file a return.

Individuals Claiming Income Tax or Capital Gains Tax Reliefs

If you want to claim certain tax reliefs, such as expenses related to your work or capital gains tax exemptions, you need to file a return.

People Receiving Income from Tips, Commission, Savings, Investments, or Dividends

Income not taxed at source, such as tips, commissions, interest from savings, dividends from shares, or other investments, must be reported.

For example, a waiter receiving tips or someone earning dividends from shares must include this income in their return.

Those with Income from Overseas Sources

If you receive income from outside the UK, such as foreign investments or rental income from overseas property, you must report it.

Individuals Receiving Child Benefit with Income Over £60,000

If you or your partner receive child benefit and your income exceeds £60,000, you must file a return to pay the High Income Child Benefit Charge.

Non-Residents with UK Taxable Income

Non-UK residents who have taxable income in the UK, including non-resident landlords, must file a self-assessment.

When Should You File Your Self-Assessment Tax Return?

The tax year runs from 6 April to 5 April the following year. You must file your return by 31 October if submitting a paper return, or by 31 January if filing online. Missing these deadlines can lead to penalties.

For example, for the tax year ending 5 April 2025, the online filing deadline is 31 January 2026.

How to Register for Self-Assessment

If you have never filed a return before, you must register with HMRC. This can be done online and should be completed well before the filing deadline to receive your Unique Taxpayer Reference (UTR) and set up your account.

What Happens If You Don’t Need to File?

If you do not meet any of the criteria above, you usually do not need to file a self-assessment tax return. HMRC will collect your tax through PAYE if you are an employee with no other income sources.

However, it is important to check your circumstances each year, as changes in income or relief claims may require you to file.

Practical Examples of Who Must File

• A self-employed plumber earning £15,500 a year must file a return.

  
  

• A landlord renting out a flat for £8,000 annually needs to declare this income.

  
  

• An employee receiving dividends from shares worth £600 must report this if it exceeds the dividend allowance.

  
  

• A non-resident UK property owner earning rental income must complete a return.

  
  

What Information Do You Need to Complete Your Return?

To file your self-assessment, gather:

• Details of all income sources (self-employment, employment, property, investments)

  
  

• Records of expenses and allowable deductions

  
  

• Information on any capital gains from asset sales

  
  

• Details of any tax reliefs or allowances you want to claim

  
  

Final Thoughts on Filing Self-Assessment Returns

Knowing whether you need to file a self-assessment tax return helps you stay on the right side of HMRC and avoid penalties. If you fall into any of the categories listed, register early and keep accurate records throughout the year. Filing on time ensures you pay the correct tax and can claim any reliefs you are entitled to.

If you are unsure about your situation, consider consulting a tax professional or using HMRC’s online tools for guidance. Taking action early saves stress and potential fines later.

Contact S K Punia Accountants LLP, who will be able to assist you with preparation and filing of self assessment.