What California Contractors Actually Pay for Workers' Comp

If you run a construction company in California, workers' compensation is probably your single largest insurance bill — and the one that surprises contractors most at renewal and audit. We regularly talk with Bay Area contractors who received a quote that felt impossibly high and had no idea how it was calculated.

This guide breaks down where the numbers come from: the rate per $100 of payroll for common trades, how California's dual-wage system changes that rate, how your experience modification multiplies it, and the practical steps that actually bring premiums down.

How California workers' comp premium is calculated

Every workers' comp policy in California starts with the same basic formula:

The Workers' Compensation Insurance Rating Bureau of California (WCIRB) publishes an advisory pure premium rate for every class. That figure is the bureau's estimate of what losses and claim-handling expenses will cost per $100 of payroll. It is a benchmark, not a price: each insurer files its own rates and adds its own expenses, so two carriers can quote very different premiums on the same payroll.

For policies starting on or after September 1, 2026, the Insurance Commissioner approved advisory pure premium rates that average $1.65 per $100 of payroll across all industries — 6.6% higher than the September 1, 2025 average. That's the second straight year of increases after more than a decade of flat or falling rates. Construction is far above that statewide average.

2026 workers' comp rates by trade

The table below shows approved advisory pure premium rates per $100 of payroll effective September 1, 2026, for trades we quote often. Each trade has two codes — one for employees paid below the hourly threshold and one for employees paid at or above it.

A few notes on reading these numbers. Framing: most wood framing is rated under carpentry (5403/5432), but framing new one- and two-family homes can fall under a separate residential carpentry code, so confirm which one your work fits. Electrical: the pair is written 5190/5140, and 5190 is the low-wage (more expensive) code — it's easy to get backwards. Roofing is the most expensive construction class in the state at either wage level.

What that looks like in real dollars

Take one full-time carpenter working 2,080 hours a year, before any mod or carrier adjustments:

• Apprentice at $30/hour: $62,400 payroll × $12.075 per $100 ≈ $7,535 in pure premium.
• Journeyman at $48/hour: $99,840 payroll × $5.321 per $100 ≈ $5,312 in pure premium.

The higher-paid carpenter costs about $2,200 less to cover, even with $37,000 more in wages. That counter-intuitive result is the dual-wage system at work.

California's dual-wage rule: the cliff that catches contractors

Sixteen California construction classes are split by hourly wage. Higher-paid workers statistically have fewer and shorter claims, so their code carries a lower rate. The thresholds rose for every pair on September 1, 2026 — for carpentry, from $41 to $46 an hour.

• It's a cliff, not a slope. An employee one cent below the threshold puts all of their payroll in the low-wage code.
• It's decided employee by employee. Crew averages don't count.
• "Regular hourly wage" is defined narrowly. Overtime premium, bonuses and per diem generally don't count toward the threshold.
• Undocumented payroll goes to the expensive code. If an auditor can't confirm an employee's hourly wage from time and pay records, that payroll is typically assigned to the low-wage class.

General contractors, supervisors and office staff

There's no single "general contractor" rate in California. A general building contractor's field payroll is classified by the work employees actually perform, which often means carpentry codes for self-performing GCs. A few related points matter:

• Executive-level supervisors who only supervise — and never perform manual labor — may qualify for a separate supervisor classification with a lower rate. The criteria are strict, and one day of hands-on work can disqualify them.
• Clerical staff who never go to jobsites can be rated as clerical (8810), at a fraction of construction rates. Anyone who visits sites regularly usually can't.
• Subcontractors without their own workers' comp can be treated as your employees, with their payroll added to your policy at audit.

How your experience mod drives costs up or down

Once your business is large enough to qualify, the WCIRB calculates an experience modification (ex-mod or "mod") that compares your actual claims to the claims expected for a business of your size and trade. A 1.00 mod is average. Below 1.00 earns a credit; above 1.00 is a surcharge.

A few things owners often don't realize about the mod:

• It looks back about three years. The calculation generally uses three policy years of payroll and losses, ending roughly a year before the mod takes effect. A bad year follows you for three renewals.
• Frequency hurts more than severity. The formula weights the first portion of each claim most heavily, so several small claims usually raise your mod more than one larger claim of the same total.
• Open claims count at their reserve. If a carrier sets a high reserve on a claim that later closes for less, your mod may be calculated on the higher number. Ask for reserve reviews before the claim values are reported.
• A high mod limits your market. Many carriers won't quote above a certain mod, and some general contractors won't hire subs above 1.00 or 1.25.

9 practical ways contractors lower their workers' comp premium

1. Classify every employee correctly. Review job duties against WCIRB phraseology every year, especially if your work mix changed.
2. Document hourly wages for dual-wage classes. Keep time records that show regular hourly rates so qualifying employees land in the cheaper code at audit.
3. Separate office and outside-sales payroll where employees genuinely meet the rules — and keep them off jobsites.
4. Collect certificates of insurance from every sub before they start, and keep them current. It's the cheapest audit protection there is.
5. Report injuries the same day. Prompt reporting and the carrier's medical provider network keep claims smaller and shorter.
6. Build a return-to-work program. Offering modified duty gets injured employees back sooner and reduces lost-time costs that drive your mod.
7. Keep your safety program real. California requires every employer to maintain a written Injury and Illness Prevention Program; outdoor crews also need heat illness procedures. Carriers look for training records, not binders on a shelf.
8. Review your mod worksheet. Check for wrong payroll, claims that belong to another employer and reserves that should be reduced.
9. Shop the renewal and consider pay-as-you-go. Carrier rates differ widely for the same class. Payroll-based billing reduces the deposit and the size of audit adjustments.

If you've been hit with an unexpected bill after an audit, read our guide to common California workers' comp audit mistakes.

CSLB licensing and workers' comp

Every California employer with even one employee must carry workers' compensation. For licensed contractors there are extra rules: concrete (C-8), HVAC (C-20), asbestos abatement (C-22), roofing (C-39) and tree service licensees must already carry a policy even with no employees. Under current law, that requirement expands to nearly all CSLB license classes on January 1, 2028, so sole owners who now file an exemption should plan ahead.

Need the full picture? See our workers' compensation insurance page and our contractor general liability coverage overview.