The date-of-death value is the number that matters, not the original purchase price paid decades earlier. If the estate sells quickly after death and the market has not moved, the taxable gain can be small or close to zero, which is one reason executors are told to get that value right immediately rather than guessing later.
Improvements the deceased made without a permit complicate the date-of-death figure, because public records and online estimates only reflect what the City of Saskatoon has on file. An undocumented finished basement or a rewired panel changes the honest fair market value, and getting that number wrong in either direction creates a problem with the Canada Revenue Agency or with other beneficiaries.
This is general information, not tax advice, and every estate should confirm its own position with an accountant before filing. Get your hand-reviewed valuation from Joel Dyck.