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Workers comp for owner-builders in California: what Labor Code §3700 actually requires

When you legally need workers comp coverage as an owner-builder, the narrow exemptions, what a policy costs from State Fund vs a broker, and the friends-and-family carve-out that gets misused. Plain-language guide.

ByPermitPathLA· Sourced from CA Labor Code §3700-3712, State Fund underwriting docs, and California DIR guidance

The single most common gap for owner-builders in California is workers compensation insurance. Most homeowners pulling their own permit assume the requirement only applies to "real" employers: businesses with payroll, multiple employees, regular operations. It doesn't. California Labor Code §3700 requires workers comp coverage on virtually anyone you pay to do construction work on your property, with a few narrow exemptions that don't fit most ADU situations.

This guide explains who's covered, who's actually exempt, what a short-term policy costs, and the practical mechanics of buying one before your first paid hire.

What Labor Code §3700 actually says

The statute requires every employer in California to secure workers compensation coverage for every employee. Then Labor Code §3351 defines "employee" so broadly that almost any person you pay falls inside the definition. That includes:

  • Anyone you pay hourly or per-job, even occasional helpers
  • Day laborers from a labor pool or street corner
  • Unlicensed handymen working under your direction
  • Friends or family who get paid for their work
  • Anyone working on the job for your benefit, even if they're labeled as a "1099 contractor" but aren't really independent

The independent-contractor distinction matters because Labor Code §2750.3 (the ABC test from AB 5) makes it very hard to classify a regular helper as independent. If they're using your tools, working hours you set, doing work that's part of your project, they're an employee under California law, regardless of how the relationship is documented.

The exemptions that don't fit your ADU

Labor Code §3352 lists exemptions from the workers-comp requirement. Most don't fit ADU work:

  • Casual employment under $100/year. Applies if total payments to a single helper are under $100 across a calendar year. Useful for paying a teenager $50 to haul brush. Useless for any meaningful construction help.
  • Household employees. Domestic servants in your home (housekeepers, gardeners). Construction help on an ADU project is not domestic work.
  • Sole proprietors with no employees. The sub you hire is exempt themselves if they have no employees of their own, but YOU still need coverage for any helpers YOU directly hire.
  • CSLB-licensed contractors carrying their own coverage. The C-10 electrical sub with their own workers comp policy covers their own crew. You're not on the hook for their employees.

The practical takeaway: if you only hire CSLB-licensed subs who carry their own workers comp, and you don't personally hire any helpers, you may not need your own policy. But the moment you pay one person directly for cleanup, demo, painting, framing assist, anything, you do.

What a policy actually costs

Workers comp premiums in California are set by the Workers Compensation Insurance Rating Bureau (WCIRB) per $100 of payroll, by class code. Construction class codes are higher-risk than office work, so the rates are higher.

For a typical ADU owner-builder project with $20K-50K in helper payroll over 6-12 months, expect:

  • State Compensation Insurance Fund (State Fund). California's state-run workers comp insurer of last resort. They underwrite any business, including owner-builders, and don't decline based on size. Expect $1,200-3,500 for a 6-12 month policy at typical ADU payroll. Quotes are instant through their online portal.
  • Private broker. Better service and sometimes better rates if you have a clean record. Brokers like California Indemnity Insurance Services, Cal Comp, or local independents can shop multiple carriers. Slower to bind (1-2 weeks) but worth it if State Fund's pricing comes back high.
  • Pay-as-you-go policies. Some carriers (Hourly, Next Insurance) let you pay premium based on actual payroll reported monthly. Useful for owner-builders with unpredictable hiring patterns. Slightly higher per-dollar rates but better cash flow.

What drives your specific premium:

  • Total projected payroll
  • Class codes of the work performed (carpentry, plumbing, electrical each have their own rates)
  • Your "experience modification factor" (X-mod). Starts at 1.0 for new policies; lower for clean claims history, higher after losses.
  • Policy term (most owner-builder policies are 6-12 months)

Practical mechanics: buying the policy

State Fund is the simplest path. Their online quote tool at statefundca.com walks through:

  1. Business / entity setup. For owner-builders, register as a sole proprietor with the project address as the business address. You don't need an EIN or LLC.
  2. Estimated payroll. Give your best guess at total helper wages across the policy period. Conservative estimate is fine; they'll audit at policy end and adjust.
  3. Class codes. For general ADU construction help, you'll typically use code 5403 (carpentry) or 5645 (residential building). The system suggests codes based on what work you describe.
  4. Policy bind + payment. Most policies bind same-day after underwriting review. Deposit premium is usually 20-25% of estimated total; balance due monthly or at policy end.

Keep the certificate of insurance on file at the project site. Inspectors don't typically check it, but LADBS may ask during owner-builder permit pull, and CSLB will demand to see it if any complaint triggers an investigation.

The "incidental work" myth

Common misconception: "if my buddy only helps for a weekend, workers comp doesn't apply." That's not how the statute works. There's no hour-based threshold for coverage. If you pay someone $200 to help frame for a weekend, they're an employee under §3351 and you needed coverage during that work.

Two narrow situations are different:

  • Unpaid help that's truly volunteer. Your retired uncle who shows up to help for free, no payment in cash or trade, no promise of future compensation. Genuinely unpaid volunteers don't trigger §3700 because no employment relationship exists.
  • Helpers under the $100/year casual employment exemption. If total compensation across the entire calendar year stays under $100, the §3352 exemption applies.

Both situations carry risk. If a "volunteer" gets injured on site, they may later claim they expected compensation, and you're now in a workers comp dispute with no policy. If a "casual" helper turns into a regular by month three, you've blown the exemption and have months of uncovered exposure.

What happens if you skip coverage and someone gets hurt

If an injured worker can't recover through a comp policy because you didn't have one, they file a claim with the Uninsured Employers Benefits Trust Fund (UEBTF). The fund pays the worker. Then it bills you for everything it paid out: medical bills, indemnity, future medical, the works.

For a typical construction injury (broken arm, back injury, fall from height), UEBTF claims regularly hit $50K-250K. The fund will pursue you for the full amount, attach property liens, and refer the case to the DA for criminal prosecution under Labor Code §3700.5 (misdemeanor failure to provide coverage; up to one year in jail and $10K fine per violation).

For owner-builders on a $300K ADU project, the math is unforgiving: a $2,000 workers comp policy protects against six-figure exposure that materially exceeds the project value.

When to buy the policy

Before your first paid hire. Not after. Coverage doesn't backdate. A policy bound on Tuesday doesn't cover an injury that happened Monday.

The natural sequence: pull your owner-builder permit, line up your first sub or helper, buy the workers comp policy bound to the start date of their first day on site, then start work. Most owner-builders find this is the right moment to also get a Builder's Risk insurance policy and General Liability. The three together form the basic insurance stack.

Sources

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