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 ".
21(1)In section 318 of the [1952 c. 10.] Income Tax Act 1952 (charges on capital sums received for sale of patent rights) for the words in subsection (1) from " for the year of assessment" down to (but excluding) the proviso there shall be substituted the words " for the chargeable period in which the sum is received by him and successive chargeable periods, being charged in each period on the same fraction of the sum as the period is of six years (or such less fraction as has not already been charged). "
(2)In section 318(2) of that Act the word "tax" shall mean income tax, unless the seller of the patent rights, being a company, would be within the charge to corporation tax in respect of any proceeds of the sale not consisting of a capital sum; and where the subsection applies to charge a company to corporation tax in respect of a sum paid to it, the proviso shall not apply, but the company may, by notice in writing given to the Board not later than two years after the end of the accounting period in which the sum is paid, elect that the sum shall be treated as arising rateably in the accounting periods ending not later than six years from the beginning of that in which the sum is paid (being accounting periods during which the company remains within the charge to corporation tax as aforesaid), and there shall be made all such layments of tax and assessments to tax as are necessary to give :t to any such election.