Does living common-law in Ontario give me the right to use my partner's last name?

There is no automatic right in Ontario to take a partner's last name as a result of a common-law relationship. In Ontario, a legal name change requires a formal application under the Change of Name Act, which is available to anyone who is a resident of Ontario — married, common-law, or single. You do not need to be in any particular type of relationship to apply for a name change.

Some common-law partners informally use a partner's surname socially, which is generally tolerated in everyday life but can create complications with government identification, financial accounts, and professional licences if your legal documents say something different. Using a name that differs from your legal name for official purposes can cause problems.

If you want to legally change your surname, you must apply through ServiceOntario, pay the prescribed fee, and meet the eligibility requirements. Once approved, you receive a change of name certificate and can update your government ID, SIN, and other documents accordingly. A formal name change through the registry is the only way to have a new name recognized for all legal purposes in Ontario.