Corporation Tax Late Filing Penalty Calculator
A late limited company return means fines from two places at once: HMRC for the CT600 and Companies House for the annual accounts. This calculator shows both, plus your strike-off risk.
Your company's situation
Was the previous year's return also late?
If your company was late in the prior year, HMRC doubles the flat-rate penalties and Companies House also doubles its fines.
HMRC penalties
£100
CT600 late filing
Companies House
£750
Late annual accounts
Total estimated exposure
£977
Across HMRC + Companies House + interest
Free, no-obligation assessment. Response within 2 hours.
Total including £10,000 CT owed£10,977Full breakdown ▾
Most of this is still avoidable
Tax-geared penalty you still avoid
£1,000
About 31 days before the flat penalty steps up, and the clock toward the six-month surcharge keeps running.
Corporation Tax Late Payment Interest Calculator
The tool above doubles as a corporation tax late payment interest calculator. When a limited company pays its corporation tax bill after the nine-month-and-one-day deadline, HMRC charges daily interest on the outstanding balance. The rate is the Bank of England base rate plus 4 percentage points, currently 7.75% annually, the same rate that applies to Self Assessment, and meaningful on larger liabilities.
Interest accrues from the original due date until the tax is paid in full, and it is charged in addition to any late filing penalties from HMRC for the CT600 itself and any Companies House penalties for the statutory accounts. Use the calculator above to model your exact exposure across all three components.
HMRC Late Payment Interest Calculator for Corporation Tax
For limited companies specifically, this works as an HMRC late payment interest calculator covering corporation tax. Enter the tax owed and how many days past the payment deadline you are, and the tool returns the daily interest accrual at the current HMRC corporation tax rate, plus any associated late filing penalties.
Unlike Self Assessment, corporation tax has two separate deadlines to worry about: the payment deadline (nine months and one day after the end of the accounting period) and the filing deadline for the CT600 return (twelve months after the period end). Missing the payment deadline triggers interest immediately, even if the return itself is still within its filing window. This is one of the most common and costly mistakes directors make.
What counts as “late” for corporation tax?
Three separate things can be late, and each carries its own charges:
- Corporation tax payment: due 9 months and 1 day after the accounting period ends. Interest accrues daily from this date.
- CT600 tax return: due 12 months after the period end. Triggers HMRC late filing penalties separate from the payment interest.
- Statutory accounts at Companies House: due 9 months after period end for private companies. Triggers a separate Companies House penalty and, eventually, strike-off proceedings.
The calculator above models all three in one place so you can see your full exposure.