In Ontario, every notary is a commissioner of oaths, but not every commissioner is a notary. Here is what each can do — and which one you need.
Two roles, two statutes
In Ontario, the office of notary public is governed by the Notaries Act, RSO 1990, c N.6, and the office of commissioner for taking affidavits — commonly called a “commissioner of oaths” — is governed by the Commissioners for Taking Affidavits Act, RSO 1990, c C.17. The two roles overlap but they are not the same, and confusing them can cost you an appointment.
The shorthand
Every Ontario notary public is also a commissioner for taking affidavits — the broader role includes the narrower one. But not every commissioner is a notary. A commissioner who is not a notary can administer oaths on affidavits and statutory declarations only. They cannot certify copies, witness signatures on contracts and deeds for international use, prepare notarial certificates, or apply the notarial seal.
What a commissioner of oaths does
A commissioner administers oaths or solemn declarations on affidavits and statutory declarations. The commissioner verifies the deponent’s identity, confirms they understand the document, administers the oath or affirmation, witnesses the signing, and signs the jurat (the formal endorsement at the bottom of the document) with the date and place. Lawyers and paralegals licensed by the Law Society of Ontario are commissioners ex officio. Other people — court staff, government officials, certain elected officials — are also commissioners by statute. Any other person can apply to be appointed individually.
What a notary public can additionally do
A notary public can do everything a commissioner can do, plus: certify a copy of an original document as a true and accurate copy; witness signatures on contracts, deeds, and powers of attorney; prepare formal notarial certificates suitable for authentication by Global Affairs Canada or apostille; apply the embossed notarial seal that is internationally recognized. Section 3 of the Notaries Act also gives notaries specific authority over “mercantile transactions” and commercial instruments.
Which one do you need? Three questions
First, where is the document going? If outside Ontario or outside Canada, you need a notary public. Inside Ontario, a commissioner is usually enough. Second, does someone need a certified copy of an original? That is a notarial act — only a notary can do it. Third, what does the receiving party require? Read your document. If it says “notarized” or “before a notary public”, a commissioner will not suffice.
Common scenarios
Statutory declaration of common-law union for IRCC sponsorship: commissioner is enough; IRCC accepts Ontario commissioning. Court affidavit for an Ontario motion: commissioner. Certified copy of your degree for a foreign employer: notary only. Power of attorney for use in Florida real estate closing: notary, often with Global Affairs Canada authentication or apostille on top. Notarized travel consent letter for a child: notary; border officials worldwide expect the seal.
Frequently asked questions
Are all lawyers in Ontario also notaries?
All lawyers licensed by the Law Society of Ontario have the entitlement to be appointed notary public under the Notaries Act, but they must apply for and obtain a notary public seal to actually perform notarial acts. Most do.
Are paralegals notaries?
Both lawyers and licensed paralegals in good standing with the Law Society of Ontario are eligible for full, unrestricted, lifetime notary public appointments under the Notaries Act, R.S.O. 1990, c. N.6. Since the 2020 amendments to the Act, paralegals are appointed on the same administrative footing as lawyers — registration of signature and payment of the fee through Official Documents Services. Both lawyers and paralegals are also commissioners for taking affidavits by virtue of office under the Commissioners for Taking Affidavits Act, R.S.O. 1990, c. C.17, and O. Reg. 386/12 — that authority covers oaths and declarations and is separate from notarial work. As of March 1, 2026, articling students and Law Practice Program candidates are also commissioners by virtue of office under O. Reg. 20/26, restricted to work performed during their formal placement.
Can I use a commissioner for a document going to the US?
Usually not — US-bound documents almost always require a notarial seal and often further authentication. Use a notary public.