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November 13, 2025Every year, thousands of taxpayers across the UK are caught out by HMRC’s self-assessment penalties. Whether it’s missing the deadline by a few days, under-reporting income, or forgetting to pay on time — penalties can stack up quickly.
At Taxes Done Right, we’re here to help you stay compliant, avoid unnecessary fines, and make tax season stress-free. Let’s break down what you need to know.
🗓️ 1. Key Self-Assessment Deadlines
For the 2024/25 tax year (covering income between 6 April 2024 – 5 April 2025):
- Paper returns – due by 31 October 2025
- Online returns – due by 31 January 2026
- Tax payment deadline – also 31 January 2026
Miss these dates and penalties kick in automatically — even if you owe no tax.
💸 2. Penalties for Late Filing
HMRC’s penalty system is strict and automatic. Here’s what happens if you miss the filing deadline:
| Delay | Penalty |
|---|---|
| 1 day late | £100 fixed penalty |
| 3 months late | £10 per day (up to £900) |
| 6 months late | £300 or 5% of tax due (whichever is higher) |
| 12 months late | £300 or 5% again, or up to 100% if deliberate |
That’s right — a return filed a year late could cost over £1,600 in fines, even if no tax is owed.
💷 3. Penalties for Late Payment
If you’ve filed your return but missed payment deadlines, you’ll face:
- 5% of the unpaid tax if 30 days late
- Additional 5% at 6 months
- Another 5% at 12 months
- Interest charged daily until payment is made
So, always aim to file and pay early — even a small delay can snowball.
🕊️ 4. Reasonable Excuse – Can You Appeal?
HMRC may waive penalties if you have a reasonable excuse, such as:
- Serious illness or hospitalisation
- Death of a close relative near the deadline
- HMRC online system failure
- Postal delays outside your control
Appeals must be made within 30 days of receiving the penalty notice. Always keep evidence — e.g., GP letters, screenshots, or postal tracking receipts.
🧾 5. How to Avoid Self-Assessment Penalties
✅ Keep records organised year-round
✅ Use HMRC-recognised accounting software (we provide this FREE with our service)
✅ Don’t wait until January — file early and relax
✅ Sign up for HMRC reminders or use our Taxes Done Right client portal for alerts
✅ Get professional support before errors occur
🧠 Final Thoughts
Penalties are entirely avoidable with the right planning and support. Whether you’re a landlord, freelancer, or small business owner, we’ll make sure your return is Done Right — first time, every time.
💬 Need help with your 2024/25 return?
Get in touch today for a no-obligation quote and peace of mind that your taxes are handled properly.




