What actually makes a will legally valid in Ontario?

The formal requirements

Section 4 of the Succession Law Reform Act sets three requirements for a standard will: it is signed at its end by the testator, or by someone else in their presence and by their direction; the testator makes or acknowledges that signature in front of two or more witnesses present at the same time; and two of those witnesses then sign the will themselves, in the testator's presence.

No particular wording or form of attestation clause is required by law, though a well-drafted one makes proving the will easier later.

Who can't be a witness

A beneficiary, or the spouse of a beneficiary, who signs as a witness doesn't invalidate the will, but the gift to them is generally void unless a court later confirms the will's validity despite it. Choose witnesses who have nothing to gain under the will: neighbours, colleagues, or the lawyer's staff are the usual choices.

A witness also has to be old enough and capable enough to understand what they're witnessing, though the Act doesn't set a specific minimum age.

Holograph wills: valid but risky

Section 6 lets you make a valid will entirely in your own handwriting and signature, with no witnesses at all. It has to be wholly handwritten; a will typed on a computer and only signed by hand does not qualify, however clear the intention.

Holograph wills are valid, but they are also where most disputes about intention, capacity, and what was actually meant tend to arise, precisely because no one else was present to confirm any of it.

Remote and audio-visual witnessing

Since 2022, the witnessing requirement can be satisfied over live audio-visual technology rather than in the same room, provided at least one witness is a lawyer or other licensee of the Law Society at the time, the signing and the witnessing happen at essentially the same time, and any conditions set by regulation are met. Copies signed in counterpart by the testator and witnesses can together make up the will.

This option exists alongside, not instead of, in-person signing; either route produces a validly executed will.

When a court can excuse a mistake

Section 21.1 lets the Superior Court of Justice validate a document that doesn't meet these formal rules, if the court is satisfied it sets out the deceased's genuine testamentary intentions, or an intention to revoke, alter or revive a will. This curative power applies to deaths on or after the provision came into force in 2022, and does not extend to a document that exists only in electronic form with no fixed, signed version.

It's a safety net for a genuine mistake, not a reason to skip the formal steps when you don't have to.