Understanding your tax obligations is critical to staying compliant and avoiding unexpected penalties. If you're wondering who needs to do a self-assessment tax return in the UK, you're not alone. Every year, thousands of taxpayers miss deadlines simply because they’re unsure whether the requirement applies to them.

This in-depth guide explains what a self-assessment is, who it applies to, and how to file correctly—helping you stay HMRC-compliant while avoiding common tax traps.

What is a Self-Assessment Tax Return?

A Self-Assessment tax return is a system used by HM Revenue and Customs (HMRC) to collect Income Tax from individuals and entities whose tax is not automatically deducted from their wages or pensions.

Instead of your employer or pension provider handling your tax through PAYE (Pay As You Earn), you must calculate and report your income yourself, hence the term "self-assessment."

You must register with HMRC and submit your income details, claim allowances, and pay any outstanding tax due.

Why It’s Crucial to Know If You Need to File

Not everyone in the UK needs to file a tax return. But failure to submit one when required can lead to late filing penalties, interest on unpaid taxes, and even legal action. This is why it’s important to understand the eligibility rules and seek professional advice if you’re unsure.

Who Needs to Do a Self-Assessment Tax Return?

Here’s a detailed list of individuals and entities required to file a self-assessment tax return in the UK:

1. Self-Employed Individuals and Sole Traders

If you run your own business or work as a freelancer, contractor, or gig worker, and your income exceeds £1,000 in a tax year (before expenses), you must file a return.

Tip: Even if your business made a loss, it is often still worth filing to claim back allowable expenses or carry forward the loss.

2. Partners in a Business Partnership

All partners in a partnership must submit a Self-Assessment tax return, and the partnership itself must also file a partnership tax return.

3. Company Directors with Untaxed Income

If you’re a director of a limited company and receive untaxed income (e.g., dividends or rental income), HMRC usually expects you to file a return, unless your income is covered under PAYE and you have no other income to report.

4. Landlords and Property Owners

You must file a return if you:

  • Earn more than £1,000 annually from rental income

  • Rent out a room in your house (above the £7,500 Rent-a-Room limit)

  • Own multiple rental properties, including buy-to-lets

  • Are a non-resident landlord earning income in the UK

5. High-Income Employees (Over £100,000)

If your total income exceeds £100,000, you're required to submit a return—even if you're fully taxed at source via PAYE.

6. Individuals with Income from Abroad

If you:

  • Earn foreign income (e.g., overseas investments or employment)

  • Receive income from foreign property

  • Need to claim foreign tax reliefs

… then you must declare it through a self-assessment return.

7. Investors with Capital Gains

Selling assets like shares, property, or crypto may lead to Capital Gains Tax (CGT) obligations. If your gains exceed the annual CGT allowance, you must report and pay CGT through self-assessment.

8. Those Claiming Certain Tax Reliefs

You may need to file a tax return if you want to claim:

  • Marriage allowance

  • Gift Aid on large donations

  • Private pension contributions

  • Business expenses if you're a higher-rate taxpayer

9. People Receiving Untaxed Income

This includes:

  • Commission or bonuses not taxed at source

  • Freelance income on top of PAYE salary

  • Side hustles like online selling, affiliate marketing, or tutoring

  • Tips or casual earnings

10. Trustees and Executors of Estates

If you’re acting as a trustee or personal representative for someone’s estate, you may need to submit a return to report any income or capital gains made on behalf of the trust or estate.

11. Non-Resident Individuals with UK Income

Even if you live abroad, if you have UK-based income, such as from property or investments, you may need to file a self-assessment tax return for non-residents.

Who Doesn’t Usually Need to File?

You generally don’t need to file a self-assessment return if:

  • All your income is taxed under PAYE and you have no other earnings

  • Your only income is from a UK pension

  • You earn below £1,000 from side hustles or property (trading allowance)

However, if HMRC sends you a notice to file, you must file even if you believe you don’t meet the criteria.

Important Deadlines to Remember

  • Register for self-assessment: By 5 October following the end of the tax year

  • Paper tax return deadline: 31 October

  • Online tax return deadline: 31 January

  • Tax payment deadline: 31 January (and 31 July if you make payments on account)

Example: For the tax year 6 April 2024 to 5 April 2025, your online return is due by 31 January 2026.

What Happens If You Don't File?

Failing to submit a tax return when required can result in:

  • £100 initial penalty if you're just one day late

  • Daily penalties of £10 up to 90 days

  • Interest and surcharges on unpaid tax

  • Investigations and legal action in severe cases

How Quick Tax Returns Can Help

At QuickTaxReturns.co.uk, we simplify the self-assessment process for you. Whether you’re a landlord, contractor, or someone unsure of your filing obligations, our tax professionals:

  • Evaluate if you're required to file

  • Help you register with HMRC

  • Accurately calculate your tax liability

  • Submit your return error-free and on time

Avoid stress and penalties—get expert help at affordable rates.

Frequently Asked Questions (FAQs)

Q1: Can I file a tax return even if I don’t need to?

Yes, especially if you want to claim tax relief or declare small losses (e.g., as a freelancer or investor). This can help reduce future tax liabilities.

Q2: I’m employed and do some freelance work. Do I need to file?

If your freelance earnings exceed £1,000, you must file a tax return. If under, you may still need to file depending on total income and expenses.

Q3: I didn’t get a letter from HMRC—do I still need to file?

Yes, if you meet any of the criteria listed above. It is your legal responsibility to register and file even without a reminder from HMRC.Final Thoughts

Determining who needs to do a self-assessment tax return isn’t always straightforward. As the tax system evolves, more people find themselves unexpectedly required to file. Whether you're self-employed, renting out property, or receiving foreign income, the best approach is to stay informed and act early.

If you're unsure of your obligations or just want to ensure peace of mind, let the professionals at Quick Tax Returns handle it for you.

Don’t wait for a fine—know your status, file correctly, and stay compliant.

Need Help with Your Self-Assessment?
Call us or visit QuickTaxReturns.co.uk to get started with a no-obligation consultation today.