Free HMRC Tax Tools
Calculators and deadline checkers that give you exact numbers — not estimates — based on HMRC's published penalty schedule. All updated for 2025/26 rates.
HMRC Penalty + Interest Calculator
Enter how many days late your return is and your estimated tax bill. Get an exact breakdown of every penalty charge plus HMRC interest — with a visual showing what each threshold adds.
Penalty Appeal Deadline Checker
Enter the date on your HMRC penalty notice. Find out instantly whether your 30-day appeal window is still open, how many days you have left, and exactly what to do next.
Multi-Year Exposure Estimator
Add each year you haven't filed. Get a total across all years — penalties, interest, and tax owed — plus a voluntary disclosure saving estimate and enforcement risk assessment.
Corporation Tax Penalty Calculator
Calculate both your HMRC CT600 penalty and your Companies House late accounts fine simultaneously — the only tool that shows both charges together. Includes strike-off risk assessment.
Seen your number — ready to fix it?
The calculator tells you what you owe. Our specialists tell you how much of it you don't have to pay. Free assessment — no obligation.