When am I considered not “married” for income tax purposes?
For income tax purposes, you are no longer “married” if you and your spouse have been living separate and apart for a period of 90 days or longer. The stage of your legal separation or divorce proceeding in which you are in does not matter, provided the 90 days’ separation is met.
The Canada Revenue Agency (CRA) requires you to update your marital status as soon as the 90 days has passed since you began living separate and apart from your spouse. You may update your marital status online, over the phone or by mailing in the specified form.