20(1)Section 316 of the Income Tax Act 1952 (annual allowances for capital expenditure on purchase of patent rights) shall be amended as follows:—
(a)in subsection (1) for the words from "for each of the relevant years of assessment" down to (but excluding) the proviso there shall be substituted the words " writing-down allowances in respect of that expenditure during the writing-down period as hereinafter defined ", and for the words " income tax " in proviso (b) there shall be substituted the word " tax ";
(b)in subsection (2) for the words preceding the proviso there shall be substituted the words " The writing-down period shall be the seventeen years beginning with the chargeable period related to the expenditure ";
(c)subsection (3) shall be omitted.
(2)In section 317 of that Act for any reference to the relevant years of assessment there shall be substituted a reference to the writing-down period under section 316, but so that in subsection (4)(b) for " the number of the relevant years of assessment " there shall be substituted " the number of complete years of the writing-down period ".