6Meaning of “chargeable period”
(1)In this Act “chargeable period” means—
(a)for income tax purposes, a period of account, or
(b)for corporation tax purposes, an accounting period of a company.
(2)“Period of account” means—
(a)in the case of a person entitled to an allowance or liable to a charge in calculating the profits of his trade, profession or vocation, a period for which accounts are drawn up for the purposes of the trade, profession or vocation, and
(b)in the case of any other person entitled to an allowance or liable to a charge, a tax year.
(3)Subsection (2)(a) is subject to subsections (4) to (6).
(4)If—
(a)two periods of account overlap, or
(b)one period of account includes another,
the period common to both is to be treated as part of the first period of account only.
(5)If there is a gap between two periods of account, the gap is to be treated as part of the first period of account.
(6)If a period of account would (apart from this subsection) be longer than 18 months, that period must be treated as divided into separate periods of account—
(a)the first beginning with the start date of the original period, and
(b)each subsequent one beginning with an anniversary of that date,
so as to ensure that none of the periods of account is longer than 12 months.