Someone once said that the only sure things are death and taxes. Sometimes, those come together.
When you die, you still owe taxes for the year of your death. You could also owe back taxes, and Canada Revenue Agency will not forgive them because the person has died. After you have filed the final return for the person who has died, you can apply to CRA for a clearance certificate, which will state that they do not owe any back taxes. Until you receive this clearance certificate, which can be up to a year after the date of death, you should hold back at least some estate assets to cover any tax amounts; if you give them all away, then you can be personally responsible for paying CRA.