159.7. A taxpayer may deduct in computing income, in respect of an outlay or expense of the taxpayer for advertising space in an issue of a periodical for an advertisement directed at the Canadian market, only 1/2 of the amount of that outlay or expense if (a) the space occupied by the original editorial content in the issue is less than 80% of the space occupied by the total non-advertising content in the issue; and
(b) the outlay or expense would, but for this section, be deductible in computing the taxpayer’s income.