Rising Impact of Cumulative Trauma Claims in California Workers’ Compensation System

Author, Jadyn Brandt, Client Communications Coordinator, Rancho Mesa Insurance Services, Inc.

Claims involving Cumulative Trauma (CT) injuries are growing significantly, across California.

Data collected by the Worker’s Compensation Insurance Rating Bureau (WCIRB) shows growth of these types of claims accelerated in 2022, 2023 and 2024. The WCIRB now estimates that more than 25% of indemnity claims involve CT.

The Los Angeles area continues to see the largest concentration of CT claims; however, the recent increases have been observed state-wide.

Most CT claims are filed after an employee is terminated. Based on WCIRB claim survey data, approximately 60% of recent CT claims were filed post-termination, that’s an increase from prior studies which indicated only 40% of CT claims were filed post-term.

The rise in claims involving CT is having real effects on costs to employers, and underwriting losses.

The WCIRB reports combined ratios have exceeded 100% for the last six years and have been above 125% for the last two years. In accident year 2025, higher claim frequency, rising average medical costs, and increasing average allocated loss adjustment expenses (ALAE), led to a combined ratio of 129%, marking the highest ratio in over 15 years.

Rancho Mesa is seeking to reform California’s CT claims situation by drafting and sending letters to legislators asking for reform. If you are interested in taking action, templates are available addressed to California Senator Lola Smallwood-Cuevas and California Assembly Member Lisa Calderon at both their regional and capitol offices.