(1)This section applies if—
(a)a trade consists of or includes the working of a source of mineral deposits (within the meaning of item 7 of Table A in section 274),
(b)a balancing allowance falls to be made under this Part for the last chargeable period in which the trade is carried on,
(c)the event giving rise to the allowance is—
(i)the source of mineral deposits ceasing to be worked, or
(ii)the coming to an end of a foreign concession,
(d)the allowance is made for expenditure on a building which was constructed for occupation by, or for the welfare of, persons employed at or in connection with the working of the source of mineral deposits, and
(e)full effect cannot be given to the allowance because there are insufficient profits for that chargeable period.
(2)If this section applies, the person entitled to the allowance may claim that the balance of the allowance is to be given for the last preceding chargeable period, and so on for other preceding chargeable periods.
(3)But allowances are not to be given under subsection (2) for chargeable periods amounting in total to more than 5 years; but a proportionately reduced allowance may be given for a chargeable period of which part is required to make up the 5 years.
(4)In counting the 5 years, include any period for which an allowance might be made but cannot be given effect because there are insufficient profits.
(5)If this section applies to a company, no allowance may be given under this section so as to create or increase a loss in any accounting period.
(6)If this section applies to a company and a claim is made both under this section and under section 393A(1) of ICTA (relief for company trading losses)—
(a)effect is to be given to the claim under that section before this section is applied, and
(b)for the purposes of giving effect to the claim under that section, the allowance for which the claim under this section is made is to be disregarded.