In most Canadian provinces, a commissioner of oaths can administer oaths and witness affidavits or statutory declarations for use inside that province. A notary public can usually do that work plus certify true copies and authenticate signatures on documents meant for use outside the province or outside Canada. Quebec is the exception: a notaire is a distinct civil-law professional, and a commissioner for oaths (commissaire à l’assermentation) is a narrower office.
That distinction matters because the wrong stamp is a common reason a form is rejected by a court, a land-titles office, a university, or a foreign government.
What is a commissioner of oaths?
A commissioner of oaths — also called a commissioner for taking affidavits, depending on the province — is authorized to put a person under oath or affirmation and to witness certain sworn documents.
The commissioner’s job is procedural, not investigative. They confirm identity, confirm that the person understands they are swearing or affirming the contents, administer the oath or solemn declaration, watch the person sign, and complete the jurat (the block at the end that records when and where the oath was taken). They do not certify that the statements in the affidavit are true.
Typical documents a commissioner handles:
- affidavits for a provincial court proceeding
- statutory declarations for a provincial ministry or insurer
- some government application forms that require an oath
In Ontario, the office is governed by the Commissioners for Taking Affidavits Act. Lawyers, licensed paralegals, and students-at-law are commissioners by virtue of office and do not apply separately. Other people can be appointed when their work requires it. The Law Society of Ontario notes that commissioners may commission in person or remotely under the applicable regulation, and that a commissioner cannot notarize a document or commission their own affidavit.
What is a notary public?
A notary public in the common-law provinces is a separately appointed officer. In Ontario the office is governed by the Notaries Act. Being a lawyer or paralegal does not automatically make someone a notary; they must apply through Official Documents Services.
A notary can generally do everything a commissioner can do, and can also:
- certify that a photocopy is a true copy of an original
- witness and attest the execution of documents such as contracts, powers of attorney, and some deeds
- apply a notarial seal that other jurisdictions recognize as the starting point for authentication or an apostille
The Law Society of Ontario’s comparison is blunt on one practical point: Ontario notaries may commission remotely, but they may notarize only in person.
Alberta uses a single statute, the Notaries and Commissioners Act, for both offices. The Law Society of Alberta states that all lawyers and students-at-law are both notaries and commissioners. A commissioner in Alberta administers oaths and takes affidavits, affirmations, and declarations for use in Alberta. A notary can do that work and can also certify true copies and witness or attest execution of documents. Affidavits sworn outside Alberta before a notary can have effect in Alberta under the Alberta Evidence Act.
British Columbia uses the title commissioner for taking affidavits for the narrower oath-taking role. BC notaries are a separate profession with a broader practice than a typical notary public in Ontario or the Prairies. Lawyers in BC are also commissioners. The point for a member of the public is the same as elsewhere: if the receiving office asked for a notary, a commissioner stamp is not a substitute.
Quebec does not use the same system
Quebec’s private law is civil law. A Quebec notaire is not a “notary public” in the Ontario sense. A notaire is a licensed legal professional who drafts authentic acts, keeps originals in a minute book, and handles non-contentious work such as notarial wills, protection mandates, marriage contracts, and many real-estate closings. Training is a civil-law degree plus a master’s in notarial law and admission to the Chambre des notaires du Québec.
Quebec does not use the common-law office of notary public. For oaths, it uses commissioners for oaths (commissaires à l’assermentation). A commissioner in Quebec can administer oaths for documents intended for Quebec or for certain federal purposes. Certifying that a copy matches an original is notary work, not commissioner work.
This is the single most common source of confusion for people moving documents between Quebec and the rest of Canada. A stamp that is valid in Toronto may not be what a Quebec institution asked for, and a Quebec notarial act is not the same product as an Ontario notary’s certified copy.
Commissioner, notary, and Quebec notaire compared
Administer an oath on an affidavit for use in that province:
Commissioner (typical common-law province): Yes
Notary public (typical common-law province): Yes
Quebec notaire: Not the core office; commissioners handle oaths
Statutory declaration for a provincial form:
Commissioner: Yes
Notary public: Yes
Quebec notaire: Depends on the receiving body
Certify a true copy of a passport, diploma, or record:
Commissioner: No
Notary public: Yes
Quebec notaire: Yes, as a notarial act or certification
Documents for use in another province:
Commissioner: Often not accepted
Notary public: Usually required
Quebec notaire: Different product; confirm with the receiving office
Documents for use outside Canada:
Commissioner: No
Notary public: Starting point; apostille or authentication may still be required
Quebec notaire: Starting point; apostille or authentication may still be required
Draft a notarial will or authentic act:
Commissioner: No
Notary public: No
Quebec notaire: Yes
Give legal advice:
Commissioner: No, unless the person is separately licensed as a lawyer or notaire
Notary public: No, unless separately licensed
Quebec notaire: Yes, within notarial practice
How to tell which one you need
Ask three questions in order.
- Where will the document be used?
If it stays inside the same province and the form only asks for an oath, a commissioner is usually enough. If it leaves the province, the receiving office often wants a notary. - Does someone need a certified true copy?
Only a notary (or, in Quebec, a notaire) can do that work in the usual case. A commissioner stamp on a photocopy is not a certified copy. - What does the receiving office actually print on the form?
The form wins. If it says “commissioner for taking affidavits,” that is what it wants. If it says “notary public,” a commissioner is the wrong officer. If it is silent, call the office that will file the paper. Guessing is how people pay twice.
A land-titles example shows why the geography matters. An affidavit of execution commissioned in one province is not always accepted by another province’s land-titles system. Several provincial practices require a notary when the oath was taken outside the province where the land sits.
What a notary or commissioner does not do
Neither office, by itself, proves that the contents of a document are true. Neither is a substitute for independent legal advice. A lawyer who is also a notary can give advice in their capacity as a lawyer; the notarial seal does not create that advice.
They also do not apostille a document. Since 11 January 2024, Canada has been a party to the Hague Apostille Convention. An apostille is issued by a designated competent authority — Global Affairs Canada or a provincial ministry — not by the notary who signed the page. The notary’s seal is often a required earlier step. It is not the last step.
Common mistakes
People treat the two titles as synonyms because many lawyers hold both, and because the appointment happens in the same office visit. The receiving institution does not care that the person behind the desk could have used the other stamp.
People also assume a notary in one province can fix a document for every other province. Authority is provincial. A document sworn in Alberta for use in Alberta is not automatically valid in Ontario or Quebec.
A third mistake is paying for a notary when the form only needs a commissioner, or the reverse: saving a small fee and then having the document rejected. The cheaper officer is only cheaper if the paper is accepted.
Fees and where to find someone
Fees are not set nationally. Banks, law offices, municipal counters, and independent notaries post their own prices. Service Ontario and similar provincial counters sometimes offer commissioning on specified forms. For documents going abroad, budget for the notary fee and the separate apostille or authentication fee.
In Ontario, lawyers and paralegals are easy to find as commissioners. Notaries are listed through Official Documents Services and law offices. In Alberta, many bank and registry staff are commissioners; notaries are more often lawyers. In British Columbia, both lawyers and BC notaries provide notarial services, with different scopes. In Quebec, look for a notaire for authentic acts and certified copies, and a commissioner for oaths when that is what the form names.
Limits of this explainer
Appointment terms, remote-commissioning rules, and acceptable ID lists change by regulation. A municipality, court, or foreign consulate can impose a stricter local rule than the provincial statute. This page explains the offices. It is not legal advice and it does not replace the instructions on the form you have to file.
The short answer, restated: use a commissioner for a sworn statement that stays in the province; use a notary when you need a certified copy or a document that will leave the province; in Quebec, do not map either title onto the other without checking, because a notaire is a different profession.
SOURCES: Law Society of Ontario; Ministry of the Attorney General of Ontario; Official Documents Services (Ontario); Commissioners for Taking Affidavits Act (Ontario); Notaries Act (Ontario); Law Society of Alberta; Notaries and Commissioners Act (Alberta); Alberta Evidence Act; Global Affairs Canada; Chambre des notaires du Québec; Library of Parliament / parliamentary procedure sources for related process pages
