On September 1, 2026, California’s advisory workers’ compensation pure premium rate moves to $1.65 per $100 of payroll — a 6.6% increase. Insurance Commissioner Ricardo Lara adopted that number in July. It is lower than the 10.4% increase the Workers’ Compensation Insurance Rating Bureau of California had asked for, and it follows an 8.7% advisory increase that took effect September 1, 2025.
The rate is advisory. Carriers still file their own prices. But the direction is the same: after more than a decade of falling charged rates — down to $1.56 per $100 of payroll in 2025, the lowest in more than 50 years — the cost of the system is catching up. The WCIRB’s projected accident-year combined ratio for 2025 is 127%, up from 124% in 2024, and the second straight year above 120%. Written premium is still about $15.6 billion. Even after both advisory increases, those benchmark rates remain 46% below the 2014–2015 high.
Cumulative trauma is the driver
A cumulative trauma claim is not a fall off a ladder or a cut from a saw. It is an injury alleged to have built up over time — shoulders, backs, wrists, knees — from repetitive work. A California Workers’ Compensation Institute report released August 3 found those claims were 16.5% of all California workers’ compensation claims in 2025, up from 9.1% in 2018. Most of that jump came after 2021. It showed up in every region and every industry the researchers looked at, including places where employment was flat or down.
Los Angeles still has the highest share, at 22.9% of claims. Inland Empire / Orange County posted the largest increase, up 10 points to 19.8%. San Diego shops are not outside this. The same rules apply on a Chula Vista jobsite as they do in L.A.
The cost is not just frequency. WCIRB data cited this week shows medical-legal work on cumulative trauma claims rose 38% from 2020 to 2024, versus 2% on other claims. Allocated loss-adjustment expense hit $13,860 per indemnity claim in 2025 after about 9% annual growth since 2021. About a quarter of these claims have no medical payment in the first 18 months. Twenty-two percent are still open after five years. More than 80% have an attorney. Claims filed after a worker leaves the job almost always end up in litigation.
What this means if you run a crew
If your workers’ compensation policy renews around September 1, expect some carriers to move. Classification, payroll, and dual-wage thresholds still decide what you pay more than a headline percentage. The practical work is the same as it was last year, only the market has less slack: report injuries when they happen, keep job descriptions current, and do not wait for an application for adjudication to be the first time you hear about a sore shoulder.
California gives an employer 90 days to accept or deny a claim. Miss that window and the claim is presumed compensable. Cumulative trauma is harder than a table-saw accident because there is often no one day, no incident report, and no supervisor note. That is why so many of these files start as a denial while the medical-legal report is still out. It is also why a clean personnel file and a prompt call to the broker still matter.
Mainline places workers’ compensation for contractors and small businesses from the Chula Vista office. If your renewal is coming, or a claim is sitting in that 90-day window, call (619) 420-8600 or start a quote. We will tell you what the market will actually write, and what we need from payroll and class codes to get there.
Sources: Business Insurance, August 21, 2026; California Department of Insurance, July 10, 2026; WCIRB 2026 State of the System; California Workers’ Compensation Institute report, August 3, 2026.