An interesting idea but I feel like there are too many loopholes. What about people who incorporate holding companies for their rentals? What about people who earn their income in their corporations, and can control if they are “low income” in the year they purchase a house? If there’s a lower earning spouse, can they be the ones to list it at whatever price? Canadian cities vary greatly with their real estate markets - will the cutoff price be decided in each city? Will the cutoff only be adjusted for inflation, or will it be adjusted based on market rates?
If there is tax planning to be had, the rich will find it!
Corporate taxes - at least in Canada, you can have a year end any day of the year.
And yes, some older tax preparers don’t work in summer/fall.