(1) In this section, "premises" means an industrial building or structure within the meaning of section 268 which is not a building or structure to which section 272 applies.
(2) In estimating the amount of annual profits or gains arising or accruing from any trade the profits of which are chargeable to tax under Case I of Schedule D, there shall be allowed to be deducted, as expenses incurred in any year on account of any premises owned by the person carrying on that trade and occupied by such person for the purposes of that trade, a deduction equal to five-twelfths of the rateable valuation of those premises.
(3) In estimating the profits for any year of any of the concerns which by virtue of section 18(2) are charged under Case I(b) of Schedule D, there shall be allowed to be deducted, as expenses incurred in any year on account of any premises owned by the person carrying on the concern and occupied by such person for the purposes of that concern, a deduction equal to five-twelfths
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