(1) Section 284(3A) of the Principal Act is amended -

(a) by the substitution in paragraph (a) of "6 years" for "3 years",

(b) by the substitution in paragraph (b) of "paragraph (ba) and subsection (4)" for "subsection (4)",

(c) by the insertion after paragraph (b) of the following:

"(ba) Notwithstanding subsection (2), but subject to subsection (4), wear and tear allowances to be made to any person in respect of machinery or plant to which this subsection applies, and in respect of which capital expenditure is incurred on or after the date of the coming into operation of section 52 of the Finance Act, 2001, shall be made during a writing-down period of 6 years beginning with the first chargeable period or its basis period at the end of which the machinery or plant belongs to that person and is in use for the purposes of that person's trade, and shall be of an amount equal to -

(i) as respects the first year of the writing-down period, 50 per cent of the actual cost of the machinery or plant, including in that actual cost any expenditure in the nature of capital expenditure on that machinery or plant by means of renewal, improvement or reinstatement, and