If you have a document that needs a signature, an oath, or an official seal in Ontario, you may have been told to find either a “notary public” or a “commissioner of oaths” (formally, a “commissioner for taking affidavits”). In Ontario, these are two distinct offices, governed by separate statutes — the Notaries Act, RSO 1990, c N.6 and the Commissioners for Taking Affidavits Act, RSO 1990, c C.17. The two roles overlap in some respects but differ in others.
The short answer
A notary public in Ontario can do everything a commissioner for taking affidavits can do, plus several things a commissioner cannot. A commissioner administers oaths on affidavits and statutory declarations. A notary does that plus certifies true copies, witnesses signatures, prepares notarial certificates, and applies the embossed notarial seal recognized internationally.
What a commissioner of oaths can do
A commissioner administers oaths or affirmations on affidavits and statutory declarations. They must be satisfied you understand the document and are voluntarily swearing to its truth. They sign and stamp the document. Common uses: statutory declarations of common-law union, affidavits for Ontario court proceedings, declarations for government ministries.
What a notary public can do
Everything a commissioner can do, plus: certify a copy of an original as a true copy; witness and authenticate signatures on contracts, deeds, and powers of attorney; prepare notarial certificates that can be authenticated by Global Affairs Canada and legalised by foreign consulates.
Three questions to figure out which you need
- Where is the document going? Outside Ontario → notary. Staying in Ontario → commissioner is usually enough.
- Does someone need a certified copy of an original? Only a notary can certify true copies.
- What does the receiving party require? Read your document’s instructions — they often state “notarized” or “before a notary public” explicitly.
Common scenarios
Sponsoring a spouse for immigration: common-law declaration → IRCC accepts Ontario commissioning. A commissioner is usually enough.
Selling property in another country: notarized power of attorney → Global Affairs Canada authentication → consular legalisation. You need a notary.
Certified copy of your degree for an employer abroad: notary public only.
Frequently asked questions
Is a notary public more “official” than a commissioner?
No — both roles are equally official within their scope. The difference is breadth: notaries can do everything commissioners can, plus several things commissioners cannot.
Can a commissioner certify my passport copy?
No. Certifying a true copy is a notarial act.
Will a US bank accept a commissioned document?
Almost certainly not. US-bound documents need an Ontario notary’s seal and often further authentication.