Do I File a Return for the Year Before Death if It Was Not Yet Filed in Canada?

This answer covers Canadian federal tax law, which applies in every province.

Yes. If the person died in 2026 on or before the 2025 T1 filing due date and the 2025 return was not filed, the 2025 return and any balance owing are due 6 months after the date of death, on the same calendar day. A single final (2026) return is also required, so two returns are needed.

The legal representative, usually the executor named in the will, is responsible for ensuring returns are filed and balances owing are resolved. If a T1 return for a year before the year of death was not filed, the legal representative must make sure it is filed. A surviving spouse's own 2025 return has the same filing due date, but any balance the survivor owes must still be paid by April 30, 2026 to avoid interest.

The final return is separate. For a death between January 1 and October 31, it is due April 30 of the following year. Filing late with a balance owing can bring a penalty of 5% plus 1% for each full month late, up to 12 months, and interest compounds daily. Other dates can apply in special cases, such as self-employment, so confirm yours with a lawyer or accountant.