158(1)This paragraph applies if—U.K.
(a)a relevant period of account begins before 6th April 2005 and ends on or after that date, and
(b)in order to arrive at the profits or losses of a tax year before the tax year 2005-06 it is necessary to apportion the profits or losses of the relevant period of account to any part of that period falling in a tax year before the tax year 2005-06.
(2)A period of account is a “relevant period of account” if—
(a)section 871 applies to the period of account, and
(b)the profits or losses of the part of the period of account falling in the tax year 2005-06 are calculated in accordance with this Act.
(3)The profits or losses of the relevant period of account—
(a)are calculated in accordance with this Act (and therefore, to that extent, this Act has effect for tax years before the tax year 2005-06), and
(b)may be apportioned in accordance with section 871 to any part of the period of account falling in a tax year before the tax year 2005-06.