Key Tax Deadlines for UK Sole Traders

Introduction

Missing a tax deadline is one of the simplest — and most expensive — mistakes a sole trader can make.
HMRC applies automatic penalties for late filing and charges interest on unpaid tax, so knowing the key dates in advance helps you stay compliant and avoid unnecessary costs.

This guide explains the essential Self Assessment deadlines for sole traders, what happens if you miss them, and how to stay organised throughout the tax year.

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Core Deadlines for Sole Traders

Registering as self-employed — 5 October

If you became self-employed during the tax year, you must register with HMRC for Self Assessment by 5 October following the end of that tax year.

Example:
If you started trading in June 2024, register by 5 October 2025.

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Filing a paper tax return — 31 October

Very few sole traders use paper returns today, but if you do, HMRC must receive your return by 31 October.

Missing this date means you’ll need to file online instead.

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Filing an online tax return — 31 January

This is the most important deadline for sole traders.

Your online Self Assessment return for the previous tax year is due by midnight on 31 January.

Example:

• Tax year: 6 April 2023 → 5 April 2024
• Filing deadline: 31 January 2025

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Paying your tax bill — 31 January

Any tax you owe for the previous tax year must also be paid by 31 January.
If HMRC requires you to make payments on account, these are also due on this date.

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Payments on account — 31 January and 31 July

Some sole traders must make advance payments towards the next year’s tax bill.

If this applies to you:

• First payment on account is due 31 January
• Second payment on account is due 31 July

HMRC will tell you if payments on account are required based on your previous return.

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What Happens If You Miss a Deadline?

Late filing penalties

HMRC charges penalties even if you owe no tax.

• £100 — immediately after missing the deadline
• Additional penalties at 3 months, 6 months, and 12 months late

These can add up quickly if action isn’t taken.

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Late payment penalties

If you don’t pay your tax bill on time:

• Interest is charged daily
• Further penalties apply at 30 days, 6 months, and 12 months

Paying as soon as possible reduces the cost.

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Appeals

If you missed a deadline due to reasonable circumstances — such as illness or IT problems — you can appeal the penalty.
HMRC reviews appeals on a case-by-case basis.

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Tips for Staying Organised

Use reminders

Set calendar reminders for:

• Registration deadline
• Filing deadline
• Payment deadlines
• Payment on account dates (if relevant)

Set aside money for tax

Many sole traders put aside a percentage of each payment they receive to avoid last-minute pressure.

Start early

The online filing window opens in the spring.
There’s no benefit to waiting until January — and you’ll get your tax bill earlier.

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How QTax Helps You Meet Deadlines

QTax helps sole traders stay on track by:

• Highlighting important deadlines directly in the product
• Sending reminders well before the due dates
• Guiding you through your tax return so you can file confidently and on time

No stress, no last-minute rush — just a simple process designed around your needs.

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FAQs

What is the most important Self Assessment deadline?

The online filing and tax payment deadline — 31 January.

What if my income is low and I owe no tax?

You must still file your return.
HMRC charges late filing penalties even if no tax is due.

When can I file my return?

As soon as the tax year ends (from 6 April onwards). Filing early is perfectly acceptable.

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Conclusion

Staying on top of deadlines is essential for avoiding penalties and running your business smoothly.
By planning ahead and using digital tools designed for sole traders, you can manage your tax obligations with far less stress.