726.4.17.21. The amount to which section 726.4.17.20 refers is equal, at any time referred to therein, to the aggregate of(a) any amount deducted by the corporation under section 726.4.17.19 in computing its taxable income for a taxation year ending before that time, and
(b) 25% of each amount that became receivable by the corporation before that time but after 31 March 1998 and in respect of which the consideration given by the corporation was a property, other than a property disposed of by the corporation to any person with whom the corporation was not dealing at arm’s length, a share, depreciable property of a prescribed class or a Canadian resource property, or services, the cost of which may reasonably be regarded as having been an expenditure in respect of which an amount was included, under section 726.4.17.20, in computing the exploration base relating to certain exploration expenses of the corporation or of a person with whom the corporation was not dealing at arm’s length, incurred in a northern exploration zone.