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HMRC internal manual

Company Taxation Manual

From
HM Revenue & Customs
Updated
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CTSA: quarterly instalments: amount due at each instalment: formula

You calculate the amount of tax to be paid at each instalment date by applying the formula:

3 x CTI
   
  n

Where:

  • ‘CTI’ is the amount of the company’s total liability, as described in CTM92520, for the accounting period that is payable by instalments.
  • ‘n’ is the number of months in the accounting period. You calculate part months by dividing the number of spare days by 30 and expressing the sum as a decimal to two places, rounded arithmetically.