158.7. Subject to sections 158.8 and 158.9, the amount that a taxpayer may deduct, under section 158.3, in computing the taxpayer’s income for a taxation year, in respect of a matchable expenditure, other than a matchable expenditure no portion of which would, if this division were read without reference to this section, be deductible under section 158.3 in computing the taxpayer’s income, is deemed to be the amount determined under subparagraph c of the first paragraph of section 158.4 for the year in respect of the matchable expenditure where in the year(a) the taxpayer disposes, otherwise than in a disposition to which subsections 1 and 2 of section 544 or sections 556 to 564.1 and 565 apply, of all of the taxpayer’s right to receive production to which the matchable expenditure relates; or
(b) the taxpayer’s right to receive production to which the matchable expenditure relates has expired.