



 
Hi Carole, What you suggest is correct in Quebec because of the way that the taxes are imposed. If an item has a cost of $C then the cost with the 5% federal tax included is 1.05 × $C. The 7.5% provincial tax is then calculated on this amount so the final cost $F to your customer is
Thus if your customer gives you a credit of $F then
If you need to determine the individual taxes paid you need to be slightly more careful. The amount on which the provincial tax was calculated is $F/1.075 so the provincial tax paid was $F  ($F/1.075) which simplifies to
The amount of federal tax paid was $F/1.075  $C which simplifies to
Hence, for example if you get a credit of $200 then the provincial tax paid was
and the amount of federal tax paid was
and your cost was then $200  (13.95 + 8.86) = $177.19. I hope this helps,  


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