One of the duties of an Executor is to file a tax return, or in some cases tax returns on behalf of the deceased. The Final Return covers any taxable events between December 31 of the previous year and the date of death, so this period could be from one to 365 days. The CRA publishes a very useful guide called Preparing Returns for Deceased Persons (T4011). This is available at any Tax Services office or can be downloaded from the CRA website at:
The filing deadline for a Final Return is six months after the date of death or the normal filing deadline which is ordinarily April 30, whichever is later. For example, if a taxpayer died on July 31, 2019, the filing deadline will be April 30, 2020, because it is the latter between six months after the date of death (January 31, 2019) and the normal filing deadline of April 30, 2019.
Your advisor or accountant can assist you in determining what documentation needs to be collected to complete the deceased's final return.