Month-end accounting period
The normal-payment accounting period ends on 30 April 2026.
The payment deadline is 1 February 2027. The nine-month period ends on 31 January, not 30 January.
Corporation Tax deadline tool
Corporation Tax Payment Deadline Calculator
Calculate the standard Corporation Tax payment deadline from the accounting period end date using the normal 9 months and 1 day rule.
This tool is for the standard payment regime and does not cover quarterly instalment payment cases for large companies. HMRC calendar-period rule reviewed 26 September 2026.
Corporation Tax Payment Deadline Calculator
Calculate the standard Corporation Tax payment deadline from the end of the accounting period.
What this date means
The result is the standard Corporation Tax payment deadline based on the accounting period end you enter.
It helps with basic deadline planning when you are not in the large-company instalment regime.
Rule summary
Standard Corporation Tax payment rule
For companies within the standard payment regime, Corporation Tax is normally due 9 months and 1 day after the end of the accounting period.
HMRC counts complete calendar periods after the period end. A month-end period end gives the first day of the tenth following month. For a non-month-end, use the corresponding date nine months later plus one day; if that date does not exist, use the first day of the tenth month. Generic clamped date addition is not a safe implementation of this rule.
Large-company instalment-payment cases sit outside this standard rule and are not covered by this calculator.
Rule used by this tool
For companies within the standard payment regime, Corporation Tax is normally due 9 months and 1 day after the end of the accounting period.
Worked examples
How the result behaves in practice
Leap-year distinction in HMRC guidance
Compare period ends 28 February 2024 and 29 February 2024. Only the latter is the last day of February.
The deadlines are respectively 29 November 2024 and 1 December 2024 under HMRC CTM01800.
Turn the result into an action plan
Confirm that the company is not within a quarterly instalment regime before relying on the date.
Check late-payment interest separately if payment may miss the deadline; CT600 filing penalties are a different obligation.
Add the date to the wider compliance calendar so the payment deadline stays visible alongside filing work.
Read the guide
Corporation Tax payment deadlines
Read the supported rule, assumptions and worked examples behind this tool.
Assumptions and limits
This tool applies a published rule set directly and is designed for standard scenarios.
Assumptions
- You are calculating for the standard Corporation Tax payment regime.
- The accounting period end date is the correct end date for the relevant period.
Limits and rule basis
- This tool does not cover instalment payment rules for large companies.
- It does not determine the tax amount due or whether interest applies.
Primary sources and review date
Reviewed on . Preserved source review from the accepted scoped statutory repair; this contract migration does not re-date that review.
Applies to: Current ordinary Corporation Tax normal payment regime under HMRC CTM01800.
Reviewed scope: Known CT accounting-period end; quarterly instalment regimes and special payment dates excluded.
- HMRC CTM01800 — normal payment dates and calendar-period examples (verified 26 September 2026)Supports: normal payment dates and calendar-period examples
Review basis and change triggers
Reviewed model: corporation-tax-payment-deadline-calculator: corporation-tax-payment-hmrc-calendar-periods-reviewed-26 September 2026
- A cited source or statutory regime changes.
- Reviewed content, runtime adapter or domain implementation changes.
- A new effective period falls outside the supported scope.