What does compulsory mean?
A compulsory trade is one where practicing without valid certification is an offence. Every compulsory trade has a certifying exam, and journeypersons in compulsory trades must renew their Certificate of Qualification every year. Whether a specific person is qualified can be checked on the Skilled Trades Ontario Public Register.
The other 121 prescribed trades are voluntary: you can work in them without a certificate, and certification serves as formal proof of competency. Note that voluntary status under this Act does not remove licensing that other statutes attach to specific work.
The full list, from O. Reg. 876/21, s. 2
Last verified August 19, 2026 against O. Reg. 876/21 as consolidated on e-Laws (consolidation period beginning January 1, 2022, no amendments). Trades without a linked record are outside the construction and industrial sectors this registry covers first.
Hiring in a compulsory trade?
Whether each worker holds a valid card is checkable on the Skilled Trades Ontario Public Register, but the employer side has its own paperwork: WSIB registration before construction work begins, and municipal contractor licensing in many cities. Both are indexed on our sister site, Ontario Trade Registry: WSIB Form 1000 registration requirements and contractor licensing requirements by municipality.
Why these trades and not others?
The compulsory list is dominated by work where a mistake injures someone: electrical, gas-side refrigeration, sprinkler and fire protection, crane operation, steamfitting. Ontario recorded 18 construction and 27 industrial worker fatalities in 2024 alone. See workplace fatalities and critical injuries by sector for the Ministry of Labour counts behind that.