24U.K.For the purposes of paragraphs 19, 20 and 22(b), where a company has an accounting period beginning before the commencement date and ending on or after that date (“the straddling period”)—
(a)so much of the straddling period as falls before the commencement date, and so much of the straddling period as falls on or after that date, are to be treated as separate accounting periods, and
(b)where it is necessary to apportion an amount for the straddling period to the two separate accounting periods, it is to be apportioned—
(i)in accordance with section 1172 of CTA 2010 (time basis), or
(ii)if that method would produce a result that is unjust or unreasonable, on a just and reasonable basis.