When Do I Need to Submit My Tax Return?

Meeting your Self Assessment tax return deadline is a critical responsibility for anyone with untaxed income in the UK. If you haven’t yet submitted your Self Assessment tax return for the 2024/25 tax year, the online filing deadline is 31 January 2026.

The deadline for paper returns passed on 31 October 2025, so your only option now is to file online and pay your tax on time to avoid penalties.

Key Tax Deadlines at a Glance:

• 31 October 2025: Paper return submission deadline (already passed)
• 30 December 2025: Deadline to submit online if paying via PAYE (already passed)
• 31 January 2026: Final deadline to submit online return and pay tax
• 31 July 2026: Second payment on account deadline for the 2025/26 tax year

If you’re reading this in early January, you still have time, but not much. Whether you’re self-employed, a landlord, or have untaxed income, filing your return now is essential to avoid fines and interest.

What Is a Self Assessment Tax Return and Why Does It Matter?

Self Assessment is the system used by HM Revenue and Customs (HMRC) to collect Income Tax from individuals and businesses that earn income outside of regular employment. While most employees have their tax deducted at source through PAYE, individuals with additional or untaxed income must report it via Self Assessment.

This system ensures that everyone pays the correct amount of tax on their overall income, including earnings from self-employment, property, investments, or overseas income.

“Filing a Self Assessment tax return isn’t just about compliance; it’s about understanding and taking control of your finances.”
– Ben, Tax Specialist & Contributor at London Business Insider

Failing to complete a return on time, even when no tax is owed, can lead to penalties. Therefore, it’s not just important, it’s essential.

Who Needs to Submit a Tax Return in the UK?

Not everyone is required to file a Self Assessment tax return. In fact, most employees with straightforward income have their tax handled through PAYE.

However, the following individuals are typically required to file:

• Those who are self-employed and earned more than £1,000 during the tax year
• Individuals with property rental income over £1,000
• Anyone who received untaxed income from savings, dividends, or investments
• People liable to pay Capital Gains Tax
• Those earning over £50,000 who are subject to the High Income Child Benefit Charge
• Partners in a business partnership
• Individuals with foreign income or earnings from abroad
• Anyone who receives a formal notice to file from HMRC

Even if you don’t meet these criteria, you may choose to file a tax return voluntarily, such as when claiming Income Tax relief or proving self-employment for maternity allowance or mortgage purposes.

Unsure whether you need to file? HMRC provides a tool to help assess your filing obligations, which can be especially helpful for first-time filers.

When Does the UK Tax Year Start and End?

The UK tax year follows a fixed period: it starts on 6 April and ends on 5 April of the following year. For instance, the 2024/25 tax year runs from 6 April 2024 to 5 April 2025.

Understanding these dates is crucial because your income and allowable expenses must fall within this timeframe for them to be considered in your tax return. Accurate record-keeping and awareness of these dates are vital for avoiding delays, penalties, or discrepancies in your return.

By When Should You Register for Self Assessment?

If you’ve never submitted a Self Assessment tax return before, or haven’t done so for a previous year, you’ll need to register with HMRC by 5 October 2025 for the 2024/25 tax year.

Registration ensures that HMRC sends you the necessary details and access to your online tax account. You’ll receive your Unique Taxpayer Reference (UTR) and an activation code to use the online service. Failing to register on time could result in late filing penalties, especially if HMRC later determines you should have filed.

What Are the Key Tax Return Deadlines for Self Assessment?

Filing deadlines vary depending on how you submit your return and how you wish to pay. Here’s a summary of the critical dates:

Key Tax Return Deadlines (2024/25 Tax Year):

These dates applied to income earned from 6 April 2024 to 5 April 2025. As of January 2026, the 31 January deadline is fast approaching, so now is the time to finalise and submit your online return if you haven’t already.

When Is the Tax Payment Due and What Are “Payments on Account”?

Alongside submitting your return, you must pay any tax you owe by 31 January 2026. This includes your balancing payment for the 2024/25 tax year and potentially your first payment on account for the 2025/26 tax year if your bill is over £1,000.

What are Payments on Account?

Payments on account are advance payments towards your next tax bill. You’re usually required to make two payments:

• First payment: 31 January 2026
• Second payment: 31 July 2026

These are calculated as 50% of your previous year’s tax bill.

Example of Payments on Account

If your income reduces the following year, you can request to reduce your payments on account. Planning your payments in advance can ease financial pressure and avoid interest charges for underpayment.

What Are the Penalties for Missing Tax Return Deadlines?

Penalties for late filing or payment can escalate quickly. Here’s how it breaks down:

• 1 day late: £100 fixed penalty
• 3 months late: £10 per day for up to 90 days (up to £900)
• 6 months late: 5% of tax due or £300 (whichever is higher)
• 12 months late: Another 5% of tax due or £300 (again, whichever is higher)

For late payments, HMRC charges:

• 5% of unpaid tax after 30 days
• Another 5% after 6 months, and again after 12 months

Real-time example:

James, a freelance photographer, forgot to file his 2023/24 return and only submitted it in May 2025. He was 4 months late and received a £100 fine, plus £300 in daily penalties. He also paid 5% of his tax bill as a late payment fine.

Can You Submit Your Tax Return Early, and Should You?

Yes, you can submit your tax return early, and in most cases, it’s a smart move. HMRC allows you to file your Self Assessment return as soon as the tax year ends, which for the 2024/25 year means from 6 April 2025. Filing early gives you more control and removes the pressure of the January rush.

One key benefit is faster access to any tax refund you’re owed. It also gives you plenty of time to review your tax position, plan for payments, and spread the cost if needed. Early submission reduces the risk of last-minute errors, technical issues, or missed reliefs, offering valuable peace of mind.

Importantly, submitting early doesn’t mean paying early. Your payment deadline remains 31 January 2026, unless you choose to pay sooner to manage cash flow more effectively.

You can learn more about how Self Assessment deadlines affect your payments and refunds by reviewing this detailed HMRC guide.

How Do You File Your Tax Return: Online, Paper or Software?

There are several ways to file your Self Assessment tax return, and the right method depends on how comfortable you are with the process and how complex your tax affairs are.

Online Filing

Most individuals choose to file online via their HMRC account. It’s faster, provides instant confirmation, and allows easy amendments within 12 months.

Paper Return

If you prefer the traditional method, you can complete and post a SA100 paper form, but it must reach HMRC by 31 October 2025, but the date has passed.

Commercial Software

Complex cases, like trusts, partnerships, or non-residents, often benefit from using commercial tax software compatible with HMRC systems.

Choose the option that best suits your circumstances. Filing online is generally preferred due to its convenience and flexibility.

What If You No Longer Need to Submit a Tax Return?

If your circumstances change and you believe you no longer need to file, you must formally inform HMRC. Common reasons include:

• Ceasing self-employment
• No longer receiving untaxed income
• Stopping rental property activity
• Ending responsibility for the High Income Child Benefit Charge

Log in to your HMRC online account and request removal from Self Assessment. Don’t assume you’re exempt unless HMRC confirms it in writing. Otherwise, you may still be penalised for not filing.

Conclusion

With the 31 January 2026 deadline just weeks away, it’s vital to file your tax return for the 2024/25 tax year if you haven’t already.

Don’t risk penalties, take action now, submit online, and stay on top of your obligations before time runs out. The sooner you file, the more control and clarity you’ll have over your financial position.

Frequently Asked Questions

Can I amend my tax return after I’ve submitted it?

Yes, you can make changes to your return within 12 months of the original filing deadline. If submitted online, you can correct it through your HMRC account.

Do pensioners need to submit a Self Assessment tax return?

It depends. Pensioners with untaxed income from savings, investments, or property may still be required to file.

What happens if I submit my return but can’t pay my bill?

You can contact HMRC to set up a Time to Pay arrangement, which allows instalments. However, interest and penalties may still apply.

How do I check if HMRC received my return?

Online submissions receive instant confirmation. Paper return confirmations may take weeks. Always keep copies and postal receipts.

Is there a grace period after the deadline?

No. HMRC enforces penalties immediately after the deadline has passed, even at 12:01 am on 1 February.

Can I file a tax return if I don’t owe any tax?

Yes. If HMRC requests a return, you must complete it, even if your final tax bill is £0.

What if I live abroad, do I still need to file a UK tax return?

Yes, if you have UK income or property, you may still be liable. Non-residents must use appropriate HMRC forms or software.