About TaxPenalty.co.uk
TaxPenalty.co.uk is a free tool that helps UK taxpayers and their accountants understand their HMRC penalty exposure. We built it because HMRC’s penalty rules are genuinely complex — especially with the new Making Tax Digital ITSA regime launching from April 2026 — and most people arrive searching for answers while already stressed about a letter they’ve received.
What we cover
- MTD ITSA penalty points — the new points-based system from April 2026
- Late payment penalties — Penalty A & B, daily charges, and interest
- Self Assessment penalties — the current filing and payment penalty structure
- Points reset — when points auto-expire and how to clear them after the threshold
Our principles
- No signup required. The calculators work immediately with no account.
- No cookies or tracking. We don’t store your data or track your usage.
- No backend. All calculations run in your browser. Nothing is sent to our servers.
- Shareable results. Use the “Copy shareable link” button to send your calculation to an accountant.
- Exact HMRC rules. We use the precise penalty rates and thresholds published by HMRC, not approximations.
Limitations
This tool is guidance only. It is based on HMRC’s published rules and our best interpretation of those rules. It does not constitute professional tax advice. Penalty rates, interest rates, and rules change — always verify your position at gov.uk or with a qualified accountant before making decisions.
The Bank of England base rate used (4.75%) was last verified on 6 May 2025. HMRC adjusts interest rates when the base rate changes — always check the current rate at gov.uk.
Feedback
If you notice an error in our calculations, or if HMRC has updated a rate or rule, please let us know. We aim to keep these calculators accurate and up to date.