At death, the Income Tax Act treats most of what you own as if you sold it the moment before you died. Investments, private company shares, real estate outside your principal residence: all of it is deemed disposed at that moment, and any gain becomes taxable income in your final return. Registered accounts are treated even more plainly. The full value of your RRSP or RRIF is added to your income in the year you die, unless it passes directly to a spouse.
Most people assume their will handles this. A will directs where assets go. It does not, on its own, reduce what is owed before they get there.
You likely have the pieces in place already. Each one does its job on its own.
What they rarely do is work together as a single plan for what happens at death. A document that has not been reviewed in years. No plan for what happens to the business. Assets moving through probate when they did not need to. Individually, each gap is manageable. Together, at the wrong moment, they compound.
