The UK tax year runs from 6 April to 5 April of the following year. For example, the 2024–2025 tax year began on 6 April 2024 and ends on 5 April 2025. After the tax year ends, taxpayers have several months to prepare, file their return, and pay any tax owed.

Every year, millions of self-employed individuals, landlords, and taxpayers with untaxed income must submit a Self Assessment tax return to HMRC. Understanding the deadlines — and how they apply to your situation — helps you avoid penalties, stay compliant, and manage your finances smoothly.

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Key Deadlines to Remember

Self Assessment follows a fixed annual cycle, and HMRC expects all returns and payments to be submitted on time.

Here are the standard deadlines:

• 5 October following the year you started self employment – Deadline to register for Self Assessment if you're newly self-employed or earning untaxed income

• 31 October after the end of tax year – Deadline to submit a paper tax return

• 30 December after the end of tax year – Deadline to file online if you want tax collected through your PAYE tax code

• 31 January after the end of tax year– Deadline to:

  • Submit your online tax return

  • Pay any tax owed for the previous tax year

  • Make your first payment on account (if applicable)

🔍 Example for the 2024–2025 tax year:

• Tax year ends: 5 April 2025

• Paper filing deadline: 31 October 2025

• Online filing deadline: 31 January 2026

• Tax payment due: 31 January 2026

 

Who Needs to File?

You may need to file a Self Assessment tax return if you:

• Are self-employed or a sole trader

• Earn more than £1,000/year from freelancing, side hustle, or self employment

• Receive rental income from property

• Receive dividends, crypto earnings, or interest from overseas

• Are a company director and pay yourself through dividends

• Claimed Child Benefit and your income exceeds £60,000

• Need to pay Capital Gains Tax or have income over £150,000

 

What Happens If You Miss a Deadline?

Missing a deadline can lead to:

• Immediate £100 late filing penalty

• Additional charges after 3, 6, and 12 months

• Interest on unpaid tax, currently set at 7.75%

 

Tips to Stay Ahead

• Keep digital records and update them regularly

• Set calendar reminders for deadlines

• Use software or apps to track earnings and expenses

• Submit early to avoid the January rush

• Seek advice for complex income like crypto, rental, or foreign earnings

 

Looking Ahead: Making Tax Digital (MTD)

Starting from April 2026, self-employed individuals and landlords earning over £50,000/year will be required to comply with MTD for Income Tax, which means:

• Keeping digital records

• Submitting quarterly updates

• Using HMRC-approved accounting software

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If you are interested in free up time to be used in developing your business, allow us to take the burden of preparing and submitting your tax return for you. Get in touch for a free consultation