Notary Public vs. Commissioner of Oaths: What's the Difference and Which One Do You Need?

The words “notarized” and “commissioned” are often used as if they mean the same thing. In Ontario, they do not. Choosing the wrong service can mean a rejected court filing, a refused border document, or a delay with a bank, embassy, or government office.

The practical question is simple: do you only need a sworn signature witnessed, or do you need a document formally certified for broader use?

The Essential Distinction

A commissioner of oaths can administer oaths and affirmations and witness affidavits and statutory declarations.

A notary public can do all of that and can also certify true copies, prepare notarial certificates, and notarize documents that need broader recognition, especially outside Ontario or outside Canada.

The safest shortcut is this: every notary public can usually perform commissioner functions, but a commissioner of oaths cannot perform every notarial function.

What a Commissioner of Oaths Does

Commissioning is primarily about sworn statements.

When you attend a commissioning appointment, the commissioner generally:

1. Verifies your identity
2. Confirms that you understand the document
3. Administers an oath or solemn affirmation
4. Watches you sign the document
5. Completes the jurat or declaration certificate

The commissioner does not certify that the contents are true. The commissioner is certifying that you personally appeared, were identified, and swore or affirmed the contents.

In Ontario, commissioners are commonly used for:

• Affidavits for Ontario court matters
• Statutory declarations for government or administrative use
• Affidavits of service
• Routine sworn forms for local or domestic use

What a Notary Public Does

A notary public performs the same oath-taking and witnessing role, but with additional authority that matters in higher-stakes document work.

A notary public can usually:

• Administer oaths and affirmations
• Witness affidavits and statutory declarations
• Certify true copies of original documents
• Attach formal notarial certificates
• Notarize documents intended for other provinces or foreign countries
• Prepare documents for apostille or authentication processes

This is why notaries are commonly used for passports, degrees, powers of attorney for overseas use, corporate documents, and travel consent letters for minors.

Side-by-Side Comparison

When a Commissioner of Oaths Is Usually Enough

A commissioner of oaths is often sufficient where the document is a sworn statement for domestic use, including:

• Ontario affidavits and statutory declarations
• Sworn statements for local administrative bodies
• Affidavits filed in many Ontario proceedings
• Routine declarations for domestic transactions

If the receiving institution specifically asks for a commissioner or only requires a sworn declaration, commissioning may be all you need.

When You Should Use a Notary Public

Use a notary public where the document involves certification, broader recognition, or international use, including:

• Certified true copies of passports, diplomas, transcripts, or corporate records
• Documents for embassies, consulates, or foreign governments
• Powers of attorney for property or legal transactions abroad
• Travel consent letters for minors traveling internationally
• Documents that will later be apostilled or authenticated
• Documents where the receiving party specifically says “notarized”

If the document is headed outside Ontario, a notary is usually the correct starting point.

International Use Changes the Analysis

This is where mistakes happen most often. A person gets a declaration commissioned, sends it abroad, and then learns the foreign authority expected notarization and possibly further authentication.

For international documents, ask:

• Is notarization required?
• Will the document need apostille or authentication after notarization?
• Does the destination country require a certified translation?

If a document is leaving Canada, commissioning alone is rarely the safest assumption. Our guide to document authentication for overseas use explains the next steps after notarization.

Ontario-Specific Context

Ontario’s framework distinguishes clearly between commissioners and notaries under separate legislation and authority structures.

As a practical matter:

• Many lawyers and paralegals can act as commissioners of oaths
• Notarial services are generally provided by Ontario lawyers with notarial authority
• A notary is usually the better choice where the document may be scrutinized by a court, financial institution, embassy, or foreign authority

Cost Differences

Commissioning is often inexpensive and is sometimes offered at little or no cost for simple documents.

Notarial services typically cost more because they involve a broader certification role and greater external reliance on the notary’s seal and authority.

In general:

• Commissioning: often free to modest-cost for routine documents
• Notarization: usually a higher fee, especially for certified copies, urgent service, or international paperwork

How to Choose the Right Professional

Before booking, ask the receiving institution what they require. Specifically ask whether they need:

• A sworn affidavit or declaration
• A notarized document
• A certified true copy
• Apostille or authentication after notarization

If you are still unsure, book with a notary public. That approach avoids the common problem of using a commissioner where a notary was required.

For a practical checklist of what to bring, see our guide on how to prepare for your notary appointment. If you need certified copies, our article on what certified true copies are and when you need them is the next step.

This article is for informational purposes only and does not constitute legal advice. The exact document requirement depends on the institution, jurisdiction, and purpose of the document.