Do You Need to File a Self-Assessment Tax Return?

From self-employment to rental income, there are many reasons you may need to file a Self-Assessment return . Know the triggers and register with HMRC by 5 October if this is your first time.

There are a number of reasons why you might need to complete a self-assessment return. This includes if you are self-employed, a company director, have an annual income over £150,000 and / or have income from savings, investment or property.

When You Must File a Self-Assessment Tax Return

You must file a self-assessment tax return if any of the following apply to you during the tax year:

1. You were self-employed as a sole trader and earned more than £1,000 (before expenses).
2. You were a partner in a business partnership.
3. Your total taxable income exceeded £150,000 in the 2025–26 tax year. However, even if your income is under £150,000, other factors (such as rental income or capital gains) may still require you to file a self-assessment return.
4. You had to pay Capital Gains Tax on the sale or disposal of assets.
5. You were liable for the High Income Child Benefit Charge.
6. You had other sources of untaxed income, such as:
   • Rental income from property
   • Tips or commission
   • Savings and investment income (including dividends)
   • Foreign income

Registering for Self-Assessment for the First Time

If you need to file a self-assessment return for the first time, you must inform HMRC by 5 October following the end of the tax year. For the 2025–26 tax year (which ends on 5 April 2026), the deadline to register is 5 October 2026.

HMRC has an online tool that can help you check if you are required to submit a self-assessment return.