Entry into effect
4.—(1)  Paragraph 5 of the Schedule has effect with respect to any tax paid, deemed paid or liable to be paid, before, on or after 1 April 2019.
(2)  All other paragraphs of the Schedule have effect —
(a)with respect to taxes withheld at source, in respect of amounts paid, deemed paid or liable to be paid (whichever is the earliest), on or after 1 January 2020; and
(b)with respect to taxes other than those withheld at source, where the income is derived or received in a basis period beginning on or after 1 October 2019.