Can You Be Common-Law With a New Partner While Still Legally Married to Someone Else in Ontario?

Sometimes, and the answer depends on which law is asking. The general Family Law Act definition of spouse covers only people who are married to each other, or who entered a void or voidable marriage in good faith. At the same time, "cohabit" means to live together in a conjugal relationship, whether the couple is married or not, so a new relationship can create its own legal consequences.

For support, unmarried partners count as spouses after at least three years of continuous cohabitation, or in a relationship of some permanence if they are parents of a child together. A court deciding spousal support considers all the circumstances, including each party's means and needs, and how long the parties cohabited. Support is not automatic, because you must also show a basis for it.

A married spouse living separate and apart from the member on the date of death has no entitlement to the pre-retirement death benefit, while a common-law spouse who meets the Pension Benefits Act definition can be entitled. For tax, common-law means 12 months of cohabitation or being your child's parent, and cohabiting continues unless you live separate and apart for at least 90 days because of a breakdown. Get legal advice before you sign or file anything.