43. (1) An individual shall, in computing the individual’s income, include the amounts payable on a periodic basis that the individual receives in respect of the loss of all or part of the individual’s income from an office or employment, pursuant to an insurance plan under which the individual’s employer has made a contribution or which is administered or provided by an employee life and health trust to which the individual’s employer has made a contribution, not exceeding the limit set under subsection 2.
(2) Such limit shall be established by computing the amount by which(a) the aggregate of all such amounts received by the individual pursuant to the plan before the end of the year and after the later of the end of the year 1971 and the end of the last year in which any such amount was included in the individual’s income; exceeds
(b) the aggregate of the contributions made by the individual under the plan before the end of the year and after the later of the end of the year 1967 and the end of the last year in which any amount referred to in paragraph a was included in the individual’s income.