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 2026/27 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. This is the only tool that shows both charges together. Includes strike-off risk assessment.
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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.