421.5. For the purposes of this Part, any interest paid or payable for a period by a person on borrowed money used to acquire a passenger vehicle or a zero-emission passenger vehicle or on an amount paid or payable for such an acquisition is deemed, in computing the income of the person for a taxation year, to be the lesser of the amount paid or payable and the amount determined by the formula
(A / 30) × B.
In the formula in the first paragraph,(a) A is $250 or such other amount as may be prescribed;
(b) B is the number of days in the period in respect of which the interest is paid or payable, as the case may be.