What Are the Penalties for Filing a Late Tax Return in the UK? 

If you’ve missed the self-assessment tax return deadline, you’re not alone. Every year, thousands of people across the UK miss the 31 January cut-off. But failing to submit your return or pay your tax on time can lead to costly penalties from HMRC. 

At East London Accountants, we help individuals and businesses in London avoid late filing issues and deal with HMRC if you’ve already missed a deadline. In this guide, we’ll explain the penalties you could face and what to do if you’ve filed late. 

When Is the Tax Return Deadline? 

For most people, the self-assessment deadline for online tax returns is: 

• 31 January each year (covering the previous tax year) 

If you're submitting a paper return, the deadline is earlier: 

• 31 October of the same year 

Your payment for any tax owed is also due by 31 January. 

What Are the Late Filing Penalties? 

HMRC charges penalties in stages: 

1. Initial £100 Fine 

If your return is up to 3 months late (even by one day), you’ll be charged an automatic £100 fixed penalty. 

2. Daily Penalties 

If your return is more than 3 months late, you’ll be charged £10 per day, up to a maximum of 90 days (£900). 

3. 6-Month Penalty 

At six months late, you’ll be fined either: 

• £300, or 
• 5% of the tax due (whichever is higher) 

4. 12-Month Penalty 

If still unpaid after 12 months, you’ll face another £300 or 5% charge, whichever is greater. In serious cases (e.g. deliberate concealment), the penalty can be up to 100% of the tax due. 

What Are the Late Payment Penalties? 

Separate penalties apply for late payment of tax: 

• 30 days late: 5% of the unpaid tax 
• 6 months late: Additional 5% 
• 12 months late: Additional 5% 

Interest is also charged daily on any outstanding tax, from the due date until the tax is paid in full. 

Can You Appeal HMRC Penalties? 

Yes, if you have a reasonable excuse, such as: 

• Serious illness or hospitalisation 
• Bereavement of a close family member 
• Natural disasters 
• HMRC’s online system being unavailable 

You’ll need to submit an appeal in writing, explaining your circumstances and including supporting evidence. HMRC does not accept excuses like forgetting the deadline or being too busy. 

We can help prepare and submit your appeal professionally to increase your chances of success. 

What to Do If You've Missed the Deadline 

1. File your return as soon as possible – every day counts. 
2. Pay any outstanding tax – this reduces interest and late payment penalties. 
3. Seek advice – an accountant can help calculate what you owe and file quickly. 
4. Appeal penalties if eligible – don’t delay. 

How to Avoid Penalties in the Future 

• Work with an accountant who tracks deadlines for you 
• Keep your records updated throughout the year 
• Use cloud accounting software (like Xero or QuickBooks) 
• Submit your return well before 31 January 

Why Work with East London Accountants? 

We provide: 

• Self-assessment filing support 
• HMRC correspondence and appeals handling 
• Tax planning and deadline tracking 
• Personalised advice tailored to your situation 

Whether you’re filing late or want to avoid it next year, our qualified team has over 20 years’ experience helping clients stay compliant and stress-free. 

Book a Free Tax Return Consultation 

If you’ve missed the tax return deadline or are worried about upcoming penalties, we’re here to help. Contact East London Accountants today for a free consultation. We’ll guide you through what to do next and handle the paperwork for you.