Compulsory trades in Ontario explained: the 23 trades on the Skilled Trades Ontario list, what voluntary trades require instead, enforcement, fines, and how to check a trade.
Applies in: Ontario
One word decides whether you can legally pick up the tools in Ontario: compulsory. If a trade is compulsory, the province has made certification a condition of doing the work at all. If it is voluntary, anyone can do the work and certification is a credential you earn to prove skill. This page explains the line, lists the trades on each side of it, and shows you how to check a specific trade or a specific person before work starts.
Ontario prescribes 144 trades under the Building Opportunities in the Skilled Trades Act, 2021, usually shortened to BOSTA. Each trade has a defined scope of practice in Ontario Regulation 875/21: the list of tasks that count as the work of that trade.
Twenty-three of those 144 trades are classified as compulsory in Ontario Regulation 876/21. For those 23, you must be authorized to do the work. Authorization means one of three things:
That is the whole test. Years of experience, a job offer, or a certificate from another line of work do not substitute. There are narrow exemptions written into Ontario Regulation 877/21. The example the province names most often is a student taking part in the Ontario Youth Apprenticeship Program.
Skilled Trades Ontario is the Crown agency that runs apprenticeship and certification services under the act. The Ministry of Labour, Immigration, Training and Skills Development handles enforcement.
This is the full list from section 2 of Ontario Regulation 876/21, checked in October 2026:
Read the pattern in that list. The construction trades on it are the ones where bad work hides inside walls, pressurized systems, and refrigerant lines: electrical, plumbing, refrigeration, sheet metal, steamfitting, and sprinkler systems. The motive power group is the other big block, because brakes, steering, and fuel systems fail in public. Hairstylist is the one service trade on the list.
If you are planning training, start with the trade guides that match this list: how to become an electrician apprentice in Ontario for 309A, how to become a plumber apprentice in Ontario for 306A, and how to become an HVAC apprentice in Ontario for the 313A route. Our skilled trade certificate guide for Ontario covers the Certificate of Qualification process itself.
The other 121 prescribed trades are non-compulsory, often called voluntary trades. The province gives these examples: cabinet maker, cook, general carpenter, heavy duty equipment technician, and industrial electrician. For those trades:
One warning that matters for anyone moving provinces: compulsory status belongs to the province, not the trade. A trade that is voluntary in Ontario can be compulsory somewhere else. Check the rules where the work will happen, not where you trained. The Red Seal endorsement guide explains how certification travels once you hold it.
Ministry inspectors appointed under BOSTA check two things: whether people doing compulsory trade work are authorized, and whether the people who hired them engaged authorized workers. Both sides carry risk. Section 6 of the act covers the worker's duty to be authorized, section 7 covers the duty to engage only authorized people, and section 8 covers apprentice-to-journeyperson ratios where they apply.
Workers in a compulsory trade must carry proof of authorization and produce it when an inspector asks. That proof is a Skilled Trades Ontario document confirming a Certificate of Qualification, a provisional certificate, or a registered training agreement.
When an inspector finds a problem, the response follows a compliance framework. The inspector weighs the person's compliance history, the nature of the breach, and whether it endangers safety. The tools available, in rough order, are:
A person who receives a notice of contravention can apply to the Ontario Labour Relations Board for a review within 15 days. The board can resolve the notice by agreement, rescind it, affirm it, or reduce a penalty it finds excessive.
The province is actively using this system. From October 1, 2026 to January 31, 2027, ministry inspectors are running an enforcement initiative at sites where people may be doing electrical, sheet metal, plumbing, and motive power work, checking authorization in those compulsory trades.
Use three checks, in this order:
If you are the worker rather than the buyer, the same checks run in reverse. Confirm your trade's classification before you accept work that might sit inside a compulsory scope, and keep your proof with you on site.
| Electrician — Construction and Maintenance (309A) | Compulsory |
|---|---|
| Electrician — Domestic and Rural (309C) | Compulsory |
| Plumber (306A) | Compulsory |
| Refrigeration and Air Conditioning Systems Mechanic (313A) | Compulsory |
| Residential Air Conditioning Systems Mechanic (313D) | Compulsory |
| Sheet Metal Worker (308A) | Compulsory |
| Steamfitter (307A) | Compulsory |
| Automotive Service Technician (310S) | Compulsory |
| Hairstylist (332A) | Compulsory |
| General Carpenter (403A) | Voluntary |
| Welder (456A) | Voluntary in Ontario |
Classification from Ontario Regulation 876/21 and Skilled Trades Ontario trade listings, checked October 2026. Codes are the Ontario trade codes used in apprenticeship registration.
It means you may only do the work of that trade if you are authorized under the Building Opportunities in the Skilled Trades Act, 2021. Authorization takes three forms: a valid Certificate of Qualification, a valid Provisional Certificate of Qualification, or an apprenticeship under a valid Registered Training Agreement. Ontario prescribes 144 trades in total, and 23 of them are classified as compulsory under Ontario Regulation 876/21.
Twenty-three, out of 144 prescribed trades. The list is set in section 2 of Ontario Regulation 876/21. It covers the electrician trades, plumber, refrigeration and air conditioning systems mechanic, sheet metal worker, steamfitter, sprinkler and fire protection installer, hairstylist, and a group of motive power trades including automotive service technician and truck and coach technician.
Ontario calls these non-compulsory trades. You do not need authorization under the Building Opportunities in the Skilled Trades Act to work in one. General carpenter, cook, cabinet maker, heavy duty equipment technician, and industrial electrician are examples the province gives. Certification still exists for many voluntary trades, and employers often ask for it, but the law does not require it before you start work.
Experience alone does not authorize you. You need a Certificate of Qualification, a Provisional Certificate of Qualification, or a Registered Training Agreement as an apprentice. There is a trade equivalency route for experienced workers: Skilled Trades Ontario assesses your experience and, if it accepts it, you can challenge the certifying exam. Until you hold one of the three forms of authorization, the work itself is off limits, with narrow exemptions such as students in the Ontario Youth Apprenticeship Program.
A ministry inspector can provide education materials, issue a written demand for documents, issue a compliance order, or issue a notice of contravention with an administrative monetary penalty under Ontario Regulation 872/21. You can ask the Ontario Labour Relations Board to review a notice of contravention within 15 days of receiving it. Employers also break the law when they engage an unauthorized person to do compulsory trade work, so the risk sits on both sides of the hire.
Use the Skilled Trades Ontario Public Register. Employers, contractors, and homeowners can search it to verify that a person is authorized to work in a compulsory trade. One limit: not everyone who may legally do the work appears on the register. People working under an exemption, such as Ontario Youth Apprenticeship Program participants, may not show up.
Yes, both electrician trades are compulsory. Electrician — Construction and Maintenance is trade code 309A, and Electrician — Domestic and Rural is 309C. Plumber is 306A, Refrigeration and Air Conditioning Systems Mechanic is 313A, Residential Air Conditioning Systems Mechanic is 313D, Sheet Metal Worker is 308A, and Steamfitter is 307A.
No. General Carpenter, code 403A, is a voluntary (non-compulsory) trade in Ontario. You can work as a carpenter without a Certificate of Qualification, though many carpenters complete an apprenticeship anyway because employers, unions, and larger sites treat the certificate as proof of skill. The same work can carry a different status in another province, so check the province where you will work.
Yes. Apprentices under a registered training agreement and holders of a Certificate of Qualification or Provisional Certificate of Qualification must carry proof of their status and produce it if an inspector asks. Proof includes a Skilled Trades Ontario document confirming the certificate or the registered training agreement. People working under an exemption should carry proof that the exemption applies.
In Ontario Regulation 876/21, Prescribed Trades and Related Matters, under the Building Opportunities in the Skilled Trades Act, 2021. Section 1 lists all 144 prescribed trades and section 2 lists the 23 compulsory ones. Skilled Trades Ontario also publishes a searchable trades information list where each trade shows its classification, trade code, and whether it has a certifying exam and Red Seal endorsement.