How to Check If a Contractor or Plumber Is Licensed in Ontario

The short answer

Ontario has no single licence for a general contractor, so there is no single search that settles the question. You check the credential that matches the work in front of you. A plumber is checked as a person on a provincial register. A new-home builder is checked as a company in a builder directory. A Toronto renovator is checked against a city licence. An electrical contractor is checked by a licence number that should already be on the truck and the estimate.

Run the check that fits your job, in this order, before you pay a deposit. Each check below takes minutes. Skipping one rarely saves time. It usually just moves the discovery to the expensive part of the job.

This page is the homeowner side of the question. If you are the tradesperson who needs the credential, our guide to getting a contractor licence in Ontario walks through how each licence is obtained, and our contractor licence cost guide breaks down what each one costs.

Check 1: The person doing trade work, on the Skilled Trades Ontario register

Start here for plumbing, electrical, and refrigeration work in an existing home. Ontario sorts its 144 prescribed trades into compulsory and non-compulsory. In a compulsory trade, a person may only do the work if they hold a Certificate of Qualification, a Provisional Certificate of Qualification, or an apprenticeship under a Registered Training Agreement. Plumber is trade code 306A. Electrician — Construction and Maintenance is 309A. Refrigeration and Air Conditioning Systems Mechanic is 313A. All three are compulsory.

Skilled Trades Ontario keeps a public register of every apprentice in a compulsory trade and every holder of a Certificate of Qualification or Provisional Certificate in one. The province tells employers, contractors, and homeowners to use that register to verify that a person hired for compulsory trade work is authorized to do it.

Use it like this:

1. Ask the worker, by name, for their certificate number and trade code. Write both down exactly as given.
2. Search that name on the Public Register. Match the person and the trade, not a similar company name.
3. If the person is an apprentice, ask who the supervising certificate holder is and which employer holds the training agreement. Apprentices are legal. Unsupervised uncertified work is not.
4. If nothing comes up, ask which authorization covers the person. Some people working under an exemption, such as students in the Ontario Youth Apprenticeship Program, may not appear on the register. That explanation should be specific and easy to verify.

One limit matters. The register is the check for compulsory trades. For a non-compulsory trade, Skilled Trades Ontario verifies qualifications by email instead. Send the person's first and last name plus a date of birth or certificate number. The reply typically takes up to 10 business days. Build that wait into your schedule rather than waiving the check. Our compulsory vs voluntary trades guide lists which Ontario trades fall on which side of that line.

Check 2: A new home, in the Ontario Builder Directory

New homes run on a different system. Anyone building or selling a new home in Ontario must be licensed by the Home Construction Regulatory Authority. Tarion administers the new home warranty. The Ontario Builder Directory combines the two records in one public search.

Search the builder or vendor by its legal company name. Read the whole profile, not just the top line:

• Licence status. Licensed, and whether any conditions sit on the licence.
• History. How long the builder has been licensed and how many homes it has built.
• Regulatory record. Conditions, discipline, and convictions the authority has recorded.
• Warranty picture. The Tarion overview on the profile, including claims information and homes enrolled.

Then do the match test the directory makes possible. The licensed name on the profile should be the legal name on your purchase agreement or construction contract. Builders trade under marketing names that differ from the licensed entity. If the names do not line up, ask the builder to explain the connection in writing before you sign.

No listing at all is the loudest result the directory can give you. The authority's own guidance is blunt: a builder who is not listed may be building or selling illegally, and a buyer in that position risks financial loss and thin warranty protection. Report suspected illegal building to the authority rather than arguing it out with the seller. Our contractor licence guide explains the builder licensing process from the builder's side, including the competency step and the roughly eight-week average for a complete application.

Check 3: Renovation work in Toronto, against the city licence

Toronto is the one place in Ontario where a general renovator needs a municipal licence. Under Toronto Municipal Code Chapter 545, a business that repairs or renovates buildings in Toronto needs a Building Renovator licence, and that includes a business that only advertises renovation work in the city.

Ask for the licence number, then confirm it with Municipal Licensing and Standards. The licence is not a rubber stamp. An applicant must pass an oral exam of about 30 minutes on business practice, bylaw knowledge, and technical competency, supply identification and a criminal reference check from a police service, and file a health and safety declaration. A current licence tells you the business cleared that screen and can be found again if a job goes wrong.

Toronto's licence stops at the city boundary. Mississauga, Hamilton, Ottawa, and other Ontario municipalities run their own business licensing rules. If your contractor works across two cities, the honest question is which city licences the business holds, plural. A contractor who answers that question city by city is easier to trust than one who waves a single licence at every job in the province.

Check 4: Electrical and gas work, by licence number

Two kinds of work carry their own visible licence numbers. Use them.

For electrical work, record the Electrical Safety Authority and Electrical Contractor Registration Agency licence number before you hire. Provincial consumer guidance gives homeowners a short routine: note the number, check that the work vehicle displays it, and get a written estimate that includes the number and the permit fees. Nobody may run an electrical contracting business in Ontario without that contractor licence, and nobody may act as a master electrician without a master electrician licence. The authority also runs a contractor lookup, and it asks the public to report suspected unlicensed electrical work.

For gas and other fuel work, the check runs through the Technical Standards and Safety Authority. A business installing, repairing, servicing, removing, or maintaining fuel-burning appliances must be registered as a fuels contractor, and the technicians on site need gas technician certificates, graded G3, G2, and G1 by the size and type of equipment they may work on. Ask which registered contractor employs your technician and which certificate grade the person at your furnace holds. A 313A refrigeration certificate on its own does not cover gas work. Our gas technician guide sets out how those grades work.

Check 5: The business paper, WSIB and insurance

A licence says a person may do the work. It says nothing about what happens if someone is hurt on your property or a pipe fails a month later. Close that gap with two documents.

Ask for a Workplace Safety and Insurance Board clearance certificate for the business. Ontario's consumer guidance notes that workers and independent operators in construction must carry workplace safety and insurance coverage, with some exceptions, and it points homeowners to the board to check coverage. A clearance certificate is the document contractors hand each other on commercial sites for exactly this reason. Ask a sole operator working in your home for the same paper.

Ask for a certificate of insurance showing liability coverage, the insurer, and the policy dates. Do not accept a verbal assurance or a photo of a truck door. If the contractor will use subcontractors for part of the job, your contract should name those sub-trades and say who pays them, a point the province puts on its own contract checklist.

Verify the clearance yourself — do not just take the paper

A clearance certificate handed over at quoting time is a snapshot, and it goes stale fast. A WSIB clearance is valid for up to 90 days, and most clearances expire on fixed quarterly dates — February 20, May 20, August 20, and November 20 — so a certificate collected in March may already be expired by the time work starts in June. Do not rely on the paper: check it yourself, on the day you hire, through the WSIB's Quick Access Clearances service, which needs no login. Search by the business name, telephone number, CRA business name, address, city, or postal code, and confirm the clearance is current and in good standing — registered and up to date on premium payments and reporting. If the business does not appear, or the clearance has expired, ask for a fresh one before any deposit changes hands.

What to ask for, in one conversation

Put these questions to every finalist, and keep the answers in writing:

• What is the certificate number and trade code of the person who will do the plumbing, electrical, or refrigeration work?
• What is your Electrical Safety Authority contractor licence number, or your Technical Standards and Safety Authority contractor registration, if that is your line of work?
• Will you give me a Workplace Safety and Insurance Board clearance certificate and a certificate of insurance before we sign?
• Will the written estimate form part of the contract, so the 10 percent estimate rule protects the price?
• Who pulls the building permits, and will that duty be written into the contract?
• Can I have three references for work like mine, one recent and one from at least a year ago?

None of these questions is hostile. Licensed contractors answer them every week for general contractors and property managers. Friction at this stage is information.

Red flags the province names, and what to do about them

Ontario's consumer pages describe the recurring renovation scams in plain terms. Treat these as stop conditions, not negotiation openers:

• The door-to-door deal. A seller who happens to be working on your street, with material on the truck and a price that expires today.
• The free inspection that finds an emergency. A no-charge look at a furnace, chimney, or roof that ends with urgent, expensive work and a contract produced on the spot.
• The disappearing deposit. Pressure for a large down payment to buy materials, followed by slow starts or no starts at all.
• The paper-free job. No written estimate, no written contract, no licence number, cash preferred.

Your protections are written into consumer law, so use them early. Search the business name and the operator's own name in the Consumer Beware List for complaints and charges before you sign. Keep any deposit to a minimum. The province suggests 10 percent and says never to pay the full amount before the work is complete. Get at least three written estimates from contractors who inspected the work in person. And remember the clock you hold: a contract over $50 signed in your home can be cancelled within a 10 calendar-day cooling-off period, and a contract that includes its estimate caps the final price at 10 percent over that estimate unless you signed a change for new work or a new price.

If a check fails, walk to the next name on your list. Ontario has no shortage of licensed plumbers and renovators who will show you a register entry, a licence number, and a clearance certificate without being asked twice. Start with the ones who treat verification as routine, because it is routine for them.

Related guides

• How to get a contractor licence in Ontario — the other side of this page: how a contractor or builder actually obtains each Ontario licence, step by step.
• Contractor licence cost in Ontario — what each licence on this page costs the business that holds it, fee by fee.
• Compulsory vs voluntary trades in Ontario — the full list of 23 compulsory trades and what voluntary status changes about checking a worker.
• How to become a plumber apprentice in Ontario — how the 306A certificate you are checking is earned: 9,000 hours, three school levels, and the certifying exam.
• How to get a skilled trade certificate in Ontario — the certificate system behind the register, including the trade equivalency route for experienced workers.

Sources

• Workplace Safety and Insurance Board, Clearances — a clearance shows a business is registered and up to date on premiums and reporting; valid for up to 90 days; Quick Access Clearances needs no login —
• Ontario, Compulsory trades and enforcement (23 compulsory trades; authorization by Certificate of Qualification, Provisional Certificate, or Registered Training Agreement; homeowners may use the Skilled Trades Ontario Public Register to verify)
• Red Seal Program, Credential Verification Information (Ontario — certified tradespersons in compulsory trades listed on an online public registry; non-compulsory verification by email to Skilled Trades Ontario with name plus date of birth or certificate number, typically within 10 business days) —
• Ontario, Your rights when starting home renovations or repairs (WSIB coverage check, Skilled Trades Ontario certification, three written estimates, deposit guidance at 10 percent, contract over $50 in writing, estimate cap at 10 percent over, 10-day cooling-off period, Consumer Beware List, ESA/ECRA licence number checks)
• Ontario, Door-to-door sales and home service contracts (Consumer Protection Act rights — written contract, 10-day cooling-off period from receipt of the written copy, cancellation up to one year if the contract lacks required information or a false or misleading statement was made) —
• Home Construction Regulatory Authority, Ontario Builder Directory guide (directory shows licensing status, history, and regulatory actions; Tarion Warranty Overview and Properties data on each profile; unlisted builder may be operating illegally)
• Our verified guides, for the licence processes summarized here: contractor licence in Ontario (Toronto Building Renovator licence under Chapter 545, oral exam, East York Civic Centre office; ESA contractor licence with designated Master Electrician; TSSA fuels contractor registration under Ontario Regulation 212/01), contractor licence cost in Ontario, and compulsory vs voluntary trades in Ontario

Registers and directories change as licences are issued, renewed, and disciplined — run your check on the day you hire, not from a screenshot saved months earlier.