(1) Any allowance or charge made to or on any person under the preceding provisions of this Chapter shall, unless it is made under or by virtue of section 284(6) or 298, be made to or on that person in taxing such person's trade.
(2) Any initial allowance or wear and tear allowance made under or by virtue of section 298(1) or any balancing allowance made under or by virtue of section 298(2) shall be made by means of discharge or repayment of tax, and shall be available primarily against income from the letting of machinery or plant.
(3) Any balancing charge made under or by virtue of section 298(2) shall be made under Case IV of Schedule D.
(4) Any wear and tear allowance made to any person under or by virtue of section 284(6) shall be made in charging that person's income under Case V of Schedule D.