46.In computing the income of a taxpayer from a business that is a profession, for a taxation year ending after 1971, the following rules apply:
(a) the taxpayer may deduct the lesser of his investment interest in that business and the amount deducted under this paragraph in computing his income from that business for the immediately preceding taxation year;
(b) in the case of the taxation year 1972, the taxpayer is deemed, for the purposes of paragraph a, to have deducted for the year 1971 an amount equal to the aggregate of the 1971 accounts receivable of that business at the end of the 1971 fiscal period;
(c) the taxpayer must include in computing his income from that business any amount he has deducted under paragraph a for the preceding taxation year; and
(d) the taxpayer must include every amount which he receives during the year on account of debts in respect of that business, that were established by him to have become bad debts before the end of the 1971 fiscal period of such business.