(5)For the purposes of sub-paragraph (4) above a relevant balancing charge is a balancing charge which (apart from this paragraph) would be made for the year on the individual under [F32section 55 of the Capital Allowances Act] in respect of any [F33 machinery or plant] provided for the purposes of any trade from which any of the sums mentioned in paragraph 2(1) above are derived.(6)In ascertainin