Licensed and insured: what an Ontario plumber can prove, and how to say it so AI can quote it

Why "licensed and insured" is a question AI gets asked

"Licensed and insured plumbers in Toronto" is one of the questions we put to ChatGPT, Gemini and Google's AI Overviews in every plumbing scan, because homeowners type it before they let someone into the basement. An engine answering it has to decide which businesses it can safely call licensed. It can't check a register on your behalf in the moment; it leans on what your site, your Business Profile and the directories say.

So the question isn't whether you're licensed. It's whether the proof is written down in a form an engine can find and quote. Most plumbing sites say "licensed and insured" in the footer and nothing else. That line is easy to write and impossible to verify, so it doesn't set you apart from anyone.

What actually applies to plumbers in Ontario

Ontario has no single provincial licence for plumbing contractors the way the TSSA registers fuels contractors. What exists is a mix of a trade certificate, some city licences, and gas and safety rules. Here is what each one is.

The Certificate of Qualification (306A)

Plumber is trade 306A on Skilled Trades Ontario's list of compulsory trades. Skilled Trades Ontario says that to work in a compulsory trade you need a Certificate of Qualification, a provisional certificate, or a registered training agreement as an apprentice, and the certificate is renewed every year. The province's compulsory trades enforcement page explains that this sits under the Building Opportunities in the Skilled Trades Act, 2021, in force since January 1, 2022, and that inspectors can issue penalties.

The useful part for marketing: Skilled Trades Ontario keeps a public register that anyone can search by name or STO ID. A customer, or a journalist, or an engine's source, can check it. If your plumbers are on it, say so, and say how to check.

City licences for plumbing contractors

Some GTA cities license the business as well as the person:

• Toronto requires a Plumbing Contractor licence for any business that contracts or repairs plumbing or advertises as a plumbing contractor. It is renewed yearly. Drain work has its own drain contractor licence.
• Mississauga licenses plumbers, plumbing contractors and drain contractors. A plumbing contractor must employ at least one licensed plumber full time, and the requirements include a Certificate of Qualification and $2 million in liability insurance.
• Brampton licenses plumbing and drain laying contractors and publishes a list of licensed plumbing contractors that it updates weekly.
• Oakville removed licensing for plumbing, drain-laying and HVAC contractors in October 2025.

Rules elsewhere in the GTA differ and change, so check your own city's licensing page before you write anything about it. A city licence number is a strong, checkable fact. A licence you don't hold, or one that was abolished, is worse than saying nothing.

Gas work is TSSA work

If you install or service gas water heaters, you are doing fuels work. Ontario's gas regulation, O. Reg. 212/01, says no one may install, repair or service a gas appliance without a certificate, and no one may act as a contractor without being registered. In practice that means a TSSA-registered fuels contractor and gas technicians with the right certificate (a G2 covers typical residential water heaters). TSSA has a public search for registered fuels contractors. If you do gas work, your registration number belongs on your site.

WSIB and liability insurance

The WSIB says coverage is mandatory for most businesses in construction, including many independent operators and sole proprietors, with some exceptions. Anyone can get a WSIB clearance certificate online without logging in, and property managers often ask for one before they hire. Liability insurance isn't a single provincial rule, but Mississauga's licence sets $2 million, which gives customers a useful benchmark.

How to write it down

The goal is one place where every credential is stated plainly, with numbers where they exist, and the same facts everywhere else.

1. Make a credentials section on your About page or a short page of its own. For example: "Our plumbers hold the Plumber (306A) Certificate of Qualification from Skilled Trades Ontario. Toronto Plumbing Contractor licence #. TSSA fuels contractor registration # for gas water heaters. WSIB account in good standing; we carry $____ in liability insurance." Fill in only what is true today.
2. Tell people how to check. Link the Skilled Trades Ontario register, your city's list if it publishes one, and the TSSA search. A claim you invite people to verify reads very differently from a badge.
3. Name your people. "Mike Rossi, licensed plumber, 18 years" gives an engine a person to attach the credential to. Ask first, and never name someone who isn't certified as if they were.
4. Repeat the short version on each service page near the phone number, and in your Google Business Profile description (see our Business Profile checklist).
5. Match the directories. HomeStars and other directories have fields for licences and insurance. Use the same wording. Our guide to reviews, directories and citations covers which ones AI tools cite.
6. Date it. Certificates renew yearly. Put "Updated" with the month on the section and check it when you renew.

What not to write

• "Licensed and insured" with nothing behind it. It's not wrong, it's just invisible.
• "Licensed by the province" for the business. The Certificate of Qualification belongs to the person, not the company. Say "our plumbers hold", not "we are licensed by Ontario".
• A city licence in a city that doesn't issue one. Oakville's is gone. Don't keep an old number on the site.
• TSSA language if you don't do gas work. It invites a question you can't answer.
• "Certified" with no certifier. Name the body: Skilled Trades Ontario, TSSA, a backflow tester certification, a manufacturer program.

How this shows up in a scan

When we scan a plumbing business, the licensed-and-insured question shows which competitors the engines name for it, and which sources they cite. The copy-ready page our report drafts for plumbers includes a credentials block with blanks for the certificate, the city licence, TSSA registration and WSIB, so you only fill in the numbers. If you want to see where you stand first, our guide to checking whether AI recommends you works the same way for plumbers.