Tax Return Deadlines and Penalties: Don’t Miss Out!

Introduction

Every year, thousands of sole traders miss key Self Assessment tax deadlines — and HMRC penalties add up quickly. Whether you’re filing for the first time or just want to avoid last-minute stress, knowing the important dates (and what happens if you miss them) is essential.

In this guide, we cover all the major UK tax deadlines for sole traders, explain the penalties for filing or paying late, and share simple tips to stay organised so you never miss a deadline again.

For a full breakdown of annual deadlines, see our Guide to Sole Trader Tax Deadlines.

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Key UK Tax Deadlines for Sole Traders

Registering as Self-Employed — 5 October

If you became self-employed in the previous tax year, you must register with HMRC by 5 October.

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

Read our step-by-step Guide to Registering as Self-Employed.

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Filing a Paper Tax Return — 31 October

Very few people submit paper tax returns today, but if you choose to, HMRC must receive it by 31 October.

Miss this deadline → you must file online instead.

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Filing an Online Tax Return — 31 January

The most important deadline for sole traders:

Your 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

Your tax bill (including Class 2 and Class 4 National Insurance) must also be paid by midnight on 31 January.

If you owe more than £1,000, HMRC may require payments on account, explained below.

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Payments on Account — 31 January and 31 July

Payments on account are advance payments toward next year's tax bill.
They apply if:

• your last tax bill was over £1,000
• and <80% of tax was deducted at source (e.g., under PAYE)

Deadlines:

• First payment → 31 January
• Second payment → 31 July

If you’re unsure whether this applies to you, QTax will help clarify during the submission flow.

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Penalties for Missing Deadlines

Late Filing Penalties

HMRC charges penalties even if you owe no tax.

• £100 → immediately after missing the 31 January filing deadline
• Additional daily and fixed penalties after:
  • 3 months
  • 6 months
  • 12 months

These can escalate into hundreds of pounds if ignored.

Late Payment Penalties

If you miss the payment deadline:

• Interest is charged daily
• Additional penalties at:
  • 30 days
  • 6 months
  • 12 months

Paying as soon as possible reduces the cost.

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Appeals and Reasonable Excuses

You may appeal a penalty if you had a valid, documented reason such as:

• serious illness
• bereavement
• HMRC service outage
• technical issues beyond your control

HMRC evaluates appeals case by case.

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How to Never Miss a Self Assessment Deadline Again

Start Early

HMRC opens online filing in April.
There is no benefit to waiting until January.

Use a Deadline Calendar

Add reminders for:

• registration (5 October)
• filing deadline (31 January)
• payment deadlines (31 January + 31 July)

Keep Basic Records as You Go

Even simple notes help:

• invoices issued
• business expenses
• mileage
• income received

See our Guide to Record Keeping for Sole Traders.

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How QTax Helps You Avoid Deadline Stress

QTax is designed to make filing on time easy:

✔ Clear reminders

QTax helps you keep track of important dates so nothing creeps up on you.

✔ Simple step-by-step submission

Our filing flow guides you through everything you need for Self Assessment.
See how it works in the Product Tour.

✔ Avoid mistakes before submission

QTax highlights missing information and common errors.

✔ Fully HMRC-recognised

Submit directly through QTax with confidence.

✔ Affordable pricing

See our Pricing page for details.

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FAQs

What is the main Self Assessment deadline?

31 January — for both filing and paying.

Do I need to file if I earned no profit?

Yes. If you were self-employed, you must file a return even if profits were low or zero.

What happens if I'm late by just one day?

You’ll receive an automatic £100 penalty.

Can I amend my return after filing?

Yes — most returns can be amended online within 12 months.

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Conclusion

Tax deadlines don’t need to be stressful. With a clear understanding of the dates, a few practical reminders and a simple filing tool, staying compliant becomes far easier.

QTax helps you prepare, review and submit your Self Assessment on time — with clear guidance every step of the way.