How old do you have to be to make a will in Ontario?

In Ontario, the general rule is that you must be at least 18 years old to make a valid will. This age threshold is set out in the Succession Law Reform Act.

There are narrow exceptions. A person under 18 may make a will if they are or have been legally married, are contemplating marriage to a named person (effective only if that marriage occurs), are a member of a component of the Canadian Forces that is a regular force or placed on active service, or are a sailor at sea or in the course of a voyage. These exceptions are narrow, and outside of them, a will made by someone under 18 is not valid.

It is worth noting that the age requirement is separate from the capacity requirement. Even someone who is 18 or older must have testamentary capacity at the time they make their will — meaning they understand what they own, who their natural heirs are, and what effect the will has. Age alone does not establish capacity, and a will made during a period of mental incapacity can be challenged regardless of the testator's age.