81. When an individual has been a resident of Québec for only a part of a year,
(a) the amounts of $235, $375, $500, $3,700 and $5,600 provided for in sections 79 and 80 shall be reduced in the proportion that the number of months during which he resided in Québec during the year bears to twelve, and
(b) his salary, his net income and the net income of his spouse, while married, and that of the dependent person contemplated in paragraph b of section 695 of the Taxation Act (chapter I-3), shall be reduced in the proportion that the number of months during which they resided in Québec during such year bears to the number of months during which they resided in Canada during such year.
For the purposes of this section, the month during which an individual begins to reside in Québec or in Canada shall be excluded.