Versions of s. 21(4)(b)

in each taxation year, if any, after that preceding taxation year and before the particular year, made an election under this subsection covering the total amount that, but for that election, would have been deductible in computing the taxpayer’s income (other than exempt income or income that is exempt from tax under this Part) for each such year in respect of the borrowed money used for the exploration, development or acquisition of property, as the case may be, and