M1Where in the case of any profits or gains chargeable under Case I, II or VI of Schedule D it is necessary in order to arrive for the purposes of income tax or corporation tax at the profits or gains or losses of any year of assessment, accounting period or other period, to divide and apportion to specific periods the profits or gains or losses for any period for which the accounts have been made up, or to aggregate any such profits, gains or losses or any apportioned parts thereof, it shall be lawful to make such a division and apportionment or aggregation.

M2Any apportionment under this section shall be made in proportion to the number of months, or fractions of months, in the respective periods.