California Plumbing Contractor Insurance Requirements: A C-36 License Guide

The short version

A C-36 license has a short list of insurance-related conditions, and CSLB enforces them at the license level rather than through fines alone. Keep a $25,000 license bond in force. Carry workers' compensation if you have any employees, or file an exemption if you have none — and understand that the exemption option goes away for C-36 licensees on January 1, 2028. If your company is an LLC, add the $100,000 employee bond and general liability of at least $1,000,000. Let any of these lapse and the license is suspended; work while suspended and you are, legally, an unlicensed contractor.

This guide covers each requirement, the moment of hiring your first employee, and the penalties that apply when a plumbing company operates with a gap.

A realistic scenario

A plumber in Fresno has run a one-man service business under his own C-36 for six years with a workers' compensation exemption on file. In March he picks up a repipe contract on a 20-unit apartment building and hires two helpers for what he expects to be eight weeks. He pays them by check, keeps them busy, and plans to "sort out the insurance" once he sees whether the work keeps coming.

In May one helper cuts his hand badly on a reciprocating saw and goes to urgent care. The clinic asks for the employer's workers' compensation carrier. There is none.

Three things now happen in sequence. The helper's medical treatment and wage loss are the plumber's personal obligation; the Uninsured Employers Benefits Trust Fund may pay the worker and then pursue the plumber for reimbursement. The Division of Labor Standards Enforcement can issue a stop order and assess penalties. And the moment CSLB learns that an exempt licensee had employees, the exemption is invalid and the license is subject to suspension — which means the apartment repipe, still half done, is being performed by an unlicensed contractor whose right to be paid for it is now in question.

The plumber did not think of himself as an employer. California did, from the first hour the helpers worked.

Requirement 1: The contractor's license bond

Every active CSLB licensee must file and maintain a $25,000 contractor's license bond. The bond protects consumers and workers harmed by a licensee's violation of the Contractors State License Law; it is not insurance for the contractor, and the surety is entitled to recover from you anything it pays on your behalf.

A separate $25,000 bond of qualifying individual is also required if your license is qualified by a responsible managing employee (RME), or by a responsible managing officer (RMO) who owns less than 10 percent of the corporation's voting stock. An RMO who owns 10 percent or more files an exemption certification instead.

Bonds cancel for non-payment and when a surety exits the market. CSLB treats a lapsed bond the same way it treats lapsed workers' compensation: the license is suspended until a replacement is on file. Keep the renewal on a calendar that someone other than you also sees.

Requirement 2: Workers' compensation (or an exemption, for now)

The rule

California Labor Code section 3700 requires every employer with one or more employees to carry workers' compensation insurance. CSLB layers a licensing condition on top: a licensee must have a certificate of workers' compensation insurance on file with CSLB or a certificate of exemption stating under penalty of perjury that the licensee has no employees.

Five classifications may not use the exemption at all and must carry coverage whether or not they have employees: C-8 concrete, C-20 HVAC, C-22 asbestos abatement, C-39 roofing and C-61/D-49 tree service. C-36 plumbing is not currently one of them. A plumbing contractor with no employees may file an exemption today.

The 2028 change

Senate Bill 216 (2022) established the five-classification rule effective January 1, 2023 and scheduled a second step: beginning January 1, 2026, all licensed contractors, with or without employees, would be required to carry workers' compensation. Senate Bill 1455 (2024) postponed that second step to January 1, 2028.

What that means for a C-36 licensee:

• Through December 31, 2027, a plumber with no employees may keep a workers' compensation exemption on file.
• On January 1, 2028, under current law, the exemption option ends and every C-36 licensee will need a policy regardless of staffing.
• Legislative dates can move again. Check CSLB's workers' compensation page before relying on either date.

The moment you hire

An exemption becomes invalid the instant you hire an employee subject to California workers' compensation law. CSLB must receive proof of coverage within 90 days of that hire. The sequence that keeps you compliant is: bind the policy before the employee's first day, then send the certificate to CSLB. The 90 days is a filing deadline, not a grace period for being uninsured; under the Labor Code you are an uninsured employer from day one of the hire until the policy is in force.

Who counts as an employee is decided by California law, not by what you call the arrangement or how you pay. Helpers paid by check or cash, "1099 plumbers" working under your direction, and workers of an unlicensed subcontractor (who are generally treated as your employees under Labor Code section 2750.5) all count.

What a lapse costs

If required workers' compensation lapses, CSLB suspends the license. Work performed while the license is suspended is treated as work by an unlicensed contractor, which under California law can bar you from suing for payment and expose you to having to return amounts already paid.

Separately, the Department of Industrial Relations enforces the uninsured-employer provisions of the Labor Code:

• Criminal: Operating without required workers' compensation is a misdemeanor under Labor Code section 3700.5, punishable by a fine of not less than $10,000 and/or up to one year in county jail.
• Stop order: The Division of Labor Standards Enforcement can issue a stop order prohibiting the use of employee labor until coverage is obtained. Violating it is a separate misdemeanor (up to 60 days in jail, up to a $10,000 fine).
• Civil penalty: The greater of twice the premium that would have been paid during the uninsured period or $1,500 per employee.
• If a worker is injured: An uninsured employer pays the injured worker's benefits directly, can be sued civilly by the worker, and if the claim reaches the Workers' Compensation Appeals Board is assessed $10,000 per employee on payroll for a compensable injury (or $2,000 for a non-compensable one), up to $100,000.

These stack. The Fresno plumber in our scenario faces the helper's medical bills, a potential stop order with penalties, a license suspension that puts his repipe contract at risk, and criminal exposure, all for a policy that would have cost a fraction of any one of those items.

Requirement 3: Additional requirements for LLC licensees

Business and Professions Code sections 7071.6.5 and 7071.19 impose two requirements only on limited liability company licensees:

1. A $100,000 surety bond for the benefit of employees and workers — in addition to the $25,000 license bond.
2. General liability insurance with a cumulative limit of at least $1,000,000 for licensees with five or fewer personnel of record, plus $100,000 for each additional person of record, to a required maximum of $5,000,000. "Personnel of record" are the owners, officers and qualifying individuals listed on the license, not field employees.

For sole proprietors, partnerships and corporations, CSLB imposes no general liability requirement. That is a statement about the license law, not a recommendation; almost every customer who writes a contract will require general liability, and the LLC limits are a reasonable benchmark for everyone. See What insurance does a plumbing contractor need in California? for how the voluntary coverages fit around the mandatory ones.

What the C-36 classification covers (and why it matters for coverage)

The C-36 classification, defined in Title 16 of the California Code of Regulations section 832.36, covers providing a supply of safe water and the proper disposal of fluid waste in all structures and fixed works. It explicitly includes waste removal and on-site disposal connections; piping, storage tanks and venting for gases and liquids including vacuum, compressed air and medical gases; gas appliances, flues and gas connections (other than forced-warm-air units); water and gas piping from the owner's side of the meter; water-heating equipment including solar; and the maintenance and replacement of all of the above plus safety devices such as earthquake valves, backflow preventers and regulating valves.

That scope matters for insurance in two ways. On workers' compensation, it is why nearly all your field payroll belongs in the plumbing classifications (5183/5187) and why trying to carve it into lower-rated codes rarely survives an audit. On general liability, it is why your application should describe gas work, medical gas, backflow testing or solar thermal if you do them — a policy underwritten for residential drain cleaning may exclude or surcharge operations the C-36 permits you to perform.

Practical takeaway

Compliance for a C-36 is not complicated, but it is unforgiving: the bond and the workers' compensation record are checked by machine, and a lapse posts to your public license record before anyone calls you. Set the bond and policy renewals on a shared calendar. Decide in advance that the first hire — even a helper for one job — triggers a call to your broker before the start date, not after. If you are a sole operator, plan for the January 1, 2028 change now, because the exemption you have relied on will not survive it under current law. And if your company is an LLC, confirm that both the $100,000 bond and the liability limits are on file, because that is where otherwise careful contractors most often discover a gap.

If you are unsure whether your current CSLB record is complete, a licensed Pembroke producer can look at it with you. Ask a coverage question and include your license number.