California’s workers’ comp premium growth slowed to just 3% year-over-year in the first quarter of 2026, and on the surface that reads like a market cooling off. But the topline number masks a widening split beneath it: the accident-year 2025 combined ratio hit 127%, the highest level in more than two decades, driven largely by a surge in cumulative-trauma claims that is reshaping how carriers price risk. The gap between soft premium growth and deteriorating underwriting results, not the headline premium figure, is the signal insurers need to carry into 2027 loss-cost assumptions.
Premium Growth Slows to 3% as Charged Rates Rebound
According to WCIRB California’s 2026 State of the System report, released July 23, average insurer charged rates fell to their lowest level in more than 50 years in 2025 before beginning to plateau. That multi-decade slide reversed sharply in early 2026: average charged rates for the first quarter of 2026 rose almost 6% compared with the first quarter of 2025, ending a decade-long decline in rate levels. Yet written premium for the first quarter of 2026 was only about 3% higher than the same period in 2025, which WCIRB characterized as modest premium growth. Insurers are charging more per unit of exposure, but overall premium volume is not moving nearly as fast — a gap that points to slower payroll growth or a shift toward smaller, less exposed risk pools.
A 127% Combined Ratio Signals the Real Stress Point
The premium numbers are secondary to what is happening on the loss side. WCIRB projects a 127% combined ratio for accident year 2025 — the highest in over 20 years and the second consecutive year above 120%. California’s insurance department points to the same underlying pressures: higher medical treatment and medical-legal costs, a growing number of projected cumulative-trauma claims, and escalating costs of adjusting claims have all pushed accident-year combined ratios lower. That deterioration in California workers’ comp results stands apart from the broader national trend, where commercial lines underwriting gains have generally held up. None of the loss-side pressure shows up cleanly in a premium-growth headline, but it is exactly what actuaries will be modeling into 2027 loss-cost assumptions.
Cumulative Trauma Claims Are Reshaping Claim Frequency
The frequency side of the ledger explains much of the pressure. About 60% of recent cumulative-trauma claims are now filed after employment ends, up from roughly 40% in earlier WCIRB studies, and more than 90% of those claims are litigated and involve attorney representation. The effect on overall claims volume is stark: California’s indemnity claim frequency rose 26% from 2009 through 2025, while claim frequency excluding cumulative-trauma claims rose only 5% over the same period. In other words, nearly all of the frequency increase over the past decade and a half traces back to post-employment, heavily litigated cumulative-trauma filings rather than to a broader rise in workplace injuries.
| Metric | Figure |
|---|---|
| Q1 2026 written premium growth (y/y) | ~3% |
| Q1 2026 average charged rate change (y/y) | Almost 6% |
| Accident year 2025 combined ratio | 127% |
| CT claims filed post-termination | ~60% |
| CT claims litigated | >90% |
| Indemnity claim frequency change, 2009-2025 | +26% |
Regulators Split the Difference on the Rate Ask
Rate-setting has not kept pace with WCIRB’s own recommendations. California’s insurance commissioner adopted a 6.6% average advisory pure premium rate increase, to $1.65 per $100 of payroll, effective September 1, 2026 — well below the 10.4% increase WCIRB had requested. That gap follows a similar pattern from the prior cycle, when the commissioner adopted an 8.7% increase to $1.52 per $100 of payroll effective September 1, 2025. Commissioner Lara framed the approach as deliberately cautious: “We must be proactive in analyzing and addressing these early warning signs of a shift in market conditions in order to foster a vibrant and competitive insurance marketplace,” he said. With actuarial recommendations and adopted rates diverging for a second straight cycle, and as other states move to expand rate oversight power over commercial lines pricing, insurers are absorbing more of the cumulative-trauma cost trend than the pure premium benchmark reflects.
A Fragmenting Market Adds Another Variable
Ownership concentration in the state’s workers’ comp market is also shifting. The 10 largest workers’ comp insurers in California now account for less than 60% of premium, the lowest concentration level in decades. A more fragmented market can mean sharper price competition even as loss costs climb — another factor actuaries will weigh alongside the cumulative-trauma trend when setting 2027 loss-cost assumptions. The claims-driven pressure on results is also visible in recent consolidation activity, including one carrier’s move to acquire a workers’ comp specialist earlier this year. Carriers that built pricing models on the assumption that rate levels would keep falling from their 2025 low are now recalibrating against a claims environment where frequency, not just severity, is the moving target.
