It is my understanding that a home that was once a primary residence then had a change in use to “rental property” then later sold will result in a capital gain that must be reported on the T2091.
The T2091 creates a pro rated % for the number of years it was a primary residence vs not and applies the % to the capital gain.
This seems to be the consensus among most.
However, I have heard an alternate treatment.
CG = Proceeds - cost(FMV when the change of use occured) -outlays
(the basis of this is - the rental unit was not a personal use property)