HMRC Penalties Guide: What UK Sole Traders Need to Know
August 3, 2026 • 7 min read
HMRC penalties can add up quickly. Here's what UK sole traders need to know about late filing, late payment, and inaccuracy penalties — and how to avoid them.
Late Filing Penalties
Missing the Self Assessment filing deadline is costly. Here's what you'll face:
| How Late | Penalty |
|---|---|
| 1 day late | £100 |
| 3 months late | £100 + £10/day (up to 90 days) |
| 6 months late | 5% of tax due (or £300, whichever is higher) |
| 12 months late | 5% of tax due (or £300, whichever is higher) |
Late Payment Penalties
If you file on time but don't pay, you'll still face penalties:
| Payment Status | Penalty |
|---|---|
| 30 days late | 5% of tax due |
| 6 months late | 5% of tax due |
| 12 months late | 5% of tax due |
Plus interest charges on the outstanding amount.
Penalties for Inaccuracies
If HMRC discovers an error in your tax return, the penalty depends on the severity and whether it was careless, deliberate, or deliberate and concealed:
| Type of Error | Potential Penalty |
|---|---|
| Careless | 0-30% of extra tax due |
| Deliberate | 20-70% of extra tax due |
| Deliberate & concealed | 30-100% of extra tax due |
How to Avoid Penalties
- File on time: The online deadline is 31 January
- Pay on time: Set up a direct debit or standing order
- Keep accurate records: Use Censitio to track transactions throughout the year
- Check your return: Review all figures before submitting
- Seek help early: If you're unsure, ask an accountant
What If You've Already Missed a Deadline?
- File and pay as soon as possible — this limits further penalties
- Contact HMRC — they may be able to offer a payment plan
- Appeal if you have a reasonable excuse — serious illness, bereavement, or other exceptional circumstances
- Speak to an accountant — they can help negotiate with HMRC
Making Tax Digital (MTD) Penalties
MTD introduces additional compliance requirements:
- Late submission of quarterly updates: Penalties apply from April 2026
- Late payment of Income Tax: New penalty system being introduced
- Lack of digital records: Could lead to compliance checks
Stay ahead of MTD by using digital tools like Censitio to keep your records in order.
How Censitio Helps You Avoid Penalties
- Track transactions all year — no last-minute scramble
- HMRC-ready categories — reduce the risk of inaccuracies
- Export Excel summaries — ready for Self Assessment
- Works offline — desktop version auto-categorizes with HMRC rules
No signup needed for web app • Windows desktop available