What is the nine-month rule for corporation tax payment?
Answered 17 March 2026
Here is a comprehensive answer on the nine-month rule for corporation tax payment:
The Nine-Month Rule for Corporation Tax Payment
What the law says
The core rule is found in section 59D(1) of the Taxes Management Act (TMA) 1970: corporation tax for a given accounting period becomes due and payable nine months and one day after the end of that accounting period.
This is confirmed in the primary legislation governing interest on overpaid tax, which defines the "normal due date" as "the day following the expiry of nine months from the end of that [accounting] period". The same legislation states that "corporation tax for an accounting period becomes due and payable on the day following the expiry of nine months from the end of the accounting period".
Exception — Large Companies (Quarterly Instalment Payments): The nine-month rule applies to companies that are not large companies. Large companies are instead required to pay corporation tax in quarterly instalments under Regulation 5 of the Corporation Tax (Instalment Payments) Regulations 1998 (SI 1998/3175), with different due dates.
HMRC guidance / practice
HMRC guidance confirms the same position: the normal due and payable date for a Corporation Tax Self Assessment (CTSA) accounting period is nine months and one day after the end of the accounting period.
For the purposes of interest on overdue corporation tax, interest runs from the date the tax becomes due and payable (i.e., nine months and one day after the end of the accounting period) until the date of payment.
For interest on overpaid tax (repayment supplement), the "material date" is the last date on which corporation tax could have been paid within the nine months mentioned in section 10(1) of the principal Act.
Summary
| Rule | Detail |
|---|---|
| Standard due date | 9 months and 1 day after the end of the accounting period |
| Statutory basis | s.59D(1) TMA 1970 |
| Exception | Large companies pay by quarterly instalments under SI 1998/3175 |
Citation sources
The table below gives a brief explanation of what the legislation relevant to this subject contains. Section Explanation Section 59D(1) Taxes Management Act (TMA) 1970 The normal due and payable date for CT is nine months and one day after the end of the Accounting Period (AP). Section 455(3) Corporation Tax Act (CTA) 2010 Determines the due date for tax payable under Section 455 CTA 2010.
Treasury may by order from time to time increase or decrease the rate of interest by reference to which repayment supplements are calculated under subsection (2) above. 6 A repayment supplement shall not be payable under this section in respect of a payment made in consequence of an order or judgment of a court having power to allow interest on the payment. 7 A repayment supplement paid under this section shall be disregarded for all purposes of income tax and corporation tax. 8 In this section—
For Corporation Tax assessments the cut-off date is six months after the Earliest Due Date (EDD) which is normally nine months and one day after the company’s accounting period. For example for an assessment for the accounting period ended 30 September 1989 the EDD is the 1 July 1990 and the cut-off date would be the 1st January 1991. On any tax stood over following an appeal that is later released for collection, the interest will accrue from the 1st January 1991.
4 In subsection (3) there shall be added at the end the words “, and the reference in subsection (1A) above to the date or dates when an amount or amounts are treated as becoming due and payable in respect of the total liability of a large company for an accounting period is a reference to the date or dates when that amount or those amounts are treated as having become due and payable by the company”. 5 After subsection (9) there shall be added— 10 In subsections (1A) and (3) above “large compan
The table below gives a brief explanation of what the legislation relevant to this subject contains. Section Explanation 59D(1) Taxes Management Act (TMA) 1970 The normal due and payable date for CTSA Accounting Period (AP) is nine months and one day after the end of the AP. Regulation 5 Corporation Tax (Instalment Payments) Regulations 1998 Statutory Instrument 3175 The due and payable date for an instalment in a quarterly instalment payment (QIP) case.