Free HMRC Tax Tools
Calculators and deadline checkers built on HMRC's published penalty schedule, all updated for 2026/27 rates. Each one shows what still needs checking against your own notices.
HMRC Penalty + Interest Calculator
Enter how many days late your return is and your estimated tax bill. See every penalty charge and the HMRC interest broken down, with a visual showing what each threshold adds.
Penalty Appeal Deadline Checker
Enter the date on your HMRC penalty notice. See whether your 30-day appeal window is still open, how many days are left, and what to do next.
Multi-Year Exposure Estimator
Add each year you haven't filed. See penalties, interest and tax totalled across every year, with the enforcement risk on the oldest ones.
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.