Corporation Tax payment deadlines
Understand the standard Corporation Tax payment deadline and why it should be tracked separately from the return-filing date.
Payment date versus return date
The standard Corporation Tax payment date usually arrives earlier than the CT600 filing deadline, which is why businesses often need both dates visible at once.
HMRC CTM01800 counts complete calendar periods: a month-end accounting period gives a normal payment date on the first day of the tenth following month. A generic clamped addition of nine months followed by one day can be wrong.
For a period ending 30 April 2026, the normal payment date is 1 February 2027. For 28 February 2026, it is 1 December 2026. These are payment dates, not Company Tax Return filing deadlines.
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.
Worked examples
How the rule behaves in practice
- 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.
- 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.
Practical consequences
- A missed payment date can lead to late-payment interest even where the return itself is not yet due. CT600 late-filing penalties are a separate regime.
- That makes deadline clarity one of the simplest ways to avoid turning a tax obligation into a recovery workflow.
Important limits
- 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.
Turn the result into an action plan
- Use the payment calculator to anchor the date first.
- Check HMRC late-payment interest separately if the date has slipped; do not confuse it with CT600 late-filing penalties.
- Track the payment date in the same calendar as the CT600 filing deadline.
Use the tool
Corporation Tax Payment Deadline Calculator
Calculate the standard Corporation Tax payment deadline from the end of the accounting period.