(1) Where a person disposes of an interest or rights in or over an asset and, generally wherever on the disposal of an asset, any description of property derived from that asset remains undisposed of, the sums which under paragraphs (a) and (b) of section 552(1) are attributable to the asset shall be apportioned both for the purposes of the computation under this Chapter of the gain accruing on the disposal and for the purpose of applying this Chapter in relation to the property which remains undisposed of.
(2) Such portion of the expenditure shall be allowable as a deduction in computing under this Chapter the amount of the gain accruing on the disposal as bears the same proportion to the total of those sums as the value of the consideration for the disposal bears to the aggregate of that value and the market value of the property which remains, and the balance of the expenditure shall be attributed to the property which remains undisposed of.
(3) Any apportionment to be made in pursu
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