How Does the CRA Define a Common-Law Partner in Ontario?

The CRA treats you as living common-law when you are in a conjugal relationship with a person who is not your married spouse and that person has lived with you for at least 12 continuous months. The 12-month rule is not the only route. The person also counts if they are the parent of your child by birth or adoption, or have custody and control of your child who is wholly dependent on them.

The Income Tax Act uses similar wording: a common-law partner cohabits with you in a conjugal relationship and has done so throughout the 12-month period ending at that time, or is a parent of your child. A short separation does not necessarily end it. Once a couple cohabits, they are deemed to keep cohabiting unless they live separate and apart for at least 90 days because of a breakdown of the relationship.

If your status changes, you must tell the CRA by the end of the month after the change, and a separation counts once it has lasted more than 90 days because of a breakdown in the relationship. Your situation may have extra details, so confirm with the CRA or an accountant.