CTM92810 | CTSA: quarterly instalments: very large companies: due dates: 12 month accounting period: examples
From HM Revenue & Customs · Company Taxation Manual
Example 1
Accounting period from 1 January 2020 to 31 December 2020.
first instalment: 14 March 2020 (2 months and 13 days from the beginning of the AP)
second instalment: 14 June 2020 (3 months after the first instalment)
third instalment: 14 September 2020 (3 months after the second instalment)
final instalment: 14 December 2020 (3 months after the third instalment)