(1)Allowances shall be made in accordance with this section to a person who carries on a trade of mineral extraction in respect of qualifying expenditure incurred by him for the purposes of that trade.
(2)Subject to subsection (4) below, for the chargeable period related to the incurring of the expenditure, there shall be made to the person incurring it an allowance equal to the appropriate percentage of the excess (if any) of that expenditure over any disposal receipts which he is required to bring into account by reference to that expenditure for that chargeable period.
(3)Subject to subsection (4) below, for each of the chargeable periods following that related to the incurring of the expenditure, there shall be made to the person incurring it an allowance equal to the appropriate percentage of the excess (if any) of that expenditure over the aggregate of—
(a)the allowances made in respect of the expenditure for earlier chargeable periods by virtue of subsection (2) above and this subsection; and
(b)any disposal receipts which he is or was required to bring into account by reference to that expenditure for the chargeable period in question and any earlier chargeable periods.
(4)For a chargeable period for which, in accordance with section 101, a balancing allowance falls to be made to any person in respect of any expenditure, subsection (2) or, as the case may be, subsection (3) above shall have effect with the omission of the words “the appropriate percentage of”.
(5)Subject to subsection (6) below, in relation to expenditure which is qualifying expenditure falling within section 105, 108 or 109, other than expenditure falling within section 105(1)(b), the appropriate percentage is 25 and, in relation to all other qualifying expenditure, the appropriate percentage is 10.
(6)If a chargeable period or its basis period is part only of a year or if the period is a year of assessment but the trade has been carried on for part only of it, the percentage appropriate under subsection (5) above shall be correspondingly reduced.