10(1)In any case where—
(a)qualifying expenditure has been incurred by any person on the provision of any assets (including the construction of any works), and
(b)in any chargeable period or its basis period any of those assets is disposed of or otherwise permanently ceases (whether because of the discontinuance of the trade or for any other reason) to be used by him for the purposes of a trade of mineral extraction,
he shall bring into account as a disposal receipt in respect of that expenditure for the chargeable period related to the disposal or, as the case may be, cessation the disposal value of any asset falling within paragraph (b) above.
(2)If, at any time after a mineral asset has been acquired by any person, it begins to be used (by him or any other person) in a way which constitutes development but is neither existing permitted development nor development for the purposes of a trade of mineral extraction carried on by him, the asset shall be treated as having permanently ceased, immediately before that time, to be used by him for the purposes of that trade; and for the purposes of this subparagraph, "existing permitted development" means—
(a)development which, prior to the acquisition, had been or had begun to be lawfully carried out; and
(b)any other development for which planning permission is granted by a development order made as a general order and in force at the time of the acquisition;
and sub-paragraph (3) of paragraph 16 below applies for the purposes of this sub-paragraph as it applies for the purposes of sub-paragraph (2) of that paragraph.
(3)Subject to paragraph 18 below, subsections (6) and (7) of section 44 of the [1971 c. 68.] Finance Act 1971 (disposal value of machinery or plant) shall apply to determine the disposal value of any asset falling within subparagraph (1) above, substituting a reference to that asset for any reference in those subsections to machinery or plant.
(4)In any case where—
(a)qualifying expenditure has been incurred by any person, and
(b)in any chargeable period or its basis period he receives any capital sum which, in whole or in part, it is reasonable to attribute to that expenditure, and
(c)that capital sum does not fall to be brought into account as a disposal receipt by virtue of sub-paragraph (1) above,
he shall bring into account as a disposal receipt in respect of that expenditure for the chargeable period related to the receipt of that capital sum so much of it as is reasonably attributable to the expenditure.