CSLB classification C-4
C-4 boiler, hot water heating and steam fitting license renewal in California
Everything a C-4 license holder needs to keep the license active: when it renews, the four things that can block it, and the workers' comp rule that applies to boiler, hot water heating and steam fitting contractors.
The workers' comp rule for C-4 boiler, hot water heating and steam fitting
With employees, workers' comp is mandatory. With none, a C-4 holder can currently file a certificate of exemption — but that window is closing: under SB 216, every classification must carry comp regardless of employees starting January 1, 2028. What SB 216 changes and when.
The four things that can block your renewal
A C-4 renewal can be stopped by four independent problems: the renewal application itself, workers' comp, the $25,000 bond, and — for corporations and LLCs — Secretary of State standing. They fail separately, on different schedules, and the state won't email you about any of them. The full renewal walkthrough covers each one; if you're already past the date, here's how to limit the B&P 7031 damage.
Common questions
How often does a C-4 license renew?
Every two years, like all California contractor licenses. The license expires on the last day of a month; CSLB mails one renewal notice about 60 days out, as a courtesy only — you're responsible for renewing whether or not it arrives.
Does a C-4 boiler, hot water heating and steam fitting contractor need workers' comp?
If you have employees, yes. With no employees you can currently file an exemption — but under SB 216 that exemption ends for every classification on January 1, 2028.
What can block a C-4 renewal?
Four independent things: the renewal application itself, workers' compensation, the $25,000 contractor bond, and — for corporations and LLCs — Secretary of State entity standing. Any one of them can stop the renewal on its own.
What happens if my C-4 license expires?
Work performed while expired is unlicensed work under B&P 7031 — you can lose the right to be paid for it. The license stays renewable for up to five years (with a delinquent fee up to 50% of the renewal fee), and a retroactive petition is possible within 90 days if the delay was beyond your control.
Where does your C-4 license stand right now?
Status, renewal countdown, bond, comp, and risk flags — free, no signup.
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