Data · California · Workers’ compensation · Calendar year 2025
California workers’ compensation insurance market share (2025)
Which insurance groups write the most workers’ compensation premium in California, from the California Department of Insurance’s 2025 market share report, with each group’s 2024 share for comparison.
Key figures
- Licensed insurers wrote $11.8 billion of workers’ compensation direct premium in California in 2025, up 0.5% from $11.7 billion in 2024. 81 groups and unaffiliated insurers wrote premium in this line.
- The ten largest groups wrote 55.66% of it (55.20% for the ten largest in 2024); the five largest wrote 35.95%.
- AmTrust Financial Services Group was the largest group in 2025, with 8.73% of premium, up from 7.83% and second place in 2024. State Compensation Insurance Fund, the largest in 2024 with 9.31%, was second with 8.18%.
- Among this year’s top ten, the largest share gain from 2024 was AmTrust Financial Services Group (7.83% → 8.73%, +0.90 pp), followed by Chubb Limited Group (3.45% → 4.15%, +0.70 pp). The largest decline was State Compensation Insurance Fund (9.31% → 8.18%, −1.13 pp), followed by ICW Group (6.75% → 5.99%, −0.76 pp).
- Compared with the 2024 top ten, Fairfax Financial Group (11th in 2024) joined and Employers Holdings Group dropped out.
- Of the ten, 8 are groups with more than one company writing workers’ compensation in California; Chubb Limited Group has the most, 14. State Compensation Insurance Fund and ICW Group each have a single company writing it.
What these figures are not. Written premium is dollars, not policies or insured businesses, and the report does not count either. Market share is a share of premium written by licensed insurers; it says nothing about which groups appoint independent agencies, what they will write, or at what price.
Top 10 workers’ compensation insurance groups, 2025
| Rank | Group | Companies | 2025 $M | 2025 share | 2024 share | Change |
|---|---|---|---|---|---|---|
| 1 | AmTrust Financial Services Group | 9 | 1,027.1 | 8.73% | 7.83% | +0.90 pp |
| 2 | State Compensation Insurance Fund | 1 | 962.0 | 8.18% | 9.31% | −1.13 pp |
| 3 | Berkshire Hathaway Group | 11 | 787.6 | 6.70% | 6.40% | +0.30 pp |
| 4 | Hartford Fire & Casualty Group | 9 | 746.9 | 6.35% | 6.15% | +0.20 pp |
| 5 | ICW Group | 1 | 705.2 | 5.99% | 6.75% | −0.76 pp |
| 6 | Travelers Group | 3 | 563.9 | 4.79% | 4.92% | −0.13 pp |
| 7 | Zurich Insurance Group | 4 | 543.0 | 4.62% | 4.52% | +0.10 pp |
| 8 | Chubb Limited Group | 14 | 488.1 | 4.15% | 3.45% | +0.70 pp |
| 9 | Fairfax Financial Group | 5 | 362.9 | 3.08% | 2.85% | +0.23 pp |
| 10 | W. R. Berkley Corporation Group | 12 | 360.9 | 3.07% | 2.93% | +0.14 pp |
| Top 10 combined | 6,547.7 | 55.66% | ||||
| All 81 groups and unaffiliated insurers | 11,763.7 | 100.00% |
Change is in percentage points, 2024 to 2025. Each group is compared with the same group code in the department’s 2024 report.
State Compensation Insurance Fund is listed by the department as a single insurer (NAIC company code 35076), not as a group, and it is among the licensed insurers in the department’s file, so it is ranked here with the groups, as the department ranks it.
What this means for commercial lines agencies
A group is not a single carrier. The Companies column counts the insurers in each group that wrote workers’ compensation premium in California in 2025. Appointments, commission schedules and commission statements usually run per company, so one group can mean several statements to check.
Workers’ compensation is usually written on estimated payroll and audited after the term. The audit produces audit premium, and its commission line can arrive months after the policy expired; commission on premium audits covers how to match it to the right term.
What Lapidar checks on a commercial book, and what it does not: Lapidar for commercial lines agencies.
Methodology
- Line. Line 16, workers’ compensation. Excess workers’ compensation (Line 17.3) is a separate line in the report and is not included.
- Measure. Direct written premium of licensed (admitted) insurers in California, before reinsurance, from the department’s insurer detail file. Surplus lines insurers are not in the report.
- Groups. Insurers are grouped under the group code the department assigns in its detail file; we do not group insurers ourselves. An insurer outside any group appears on its own. Group names are shown in plain form; the department’s abbreviated name is in each row’s tooltip.
- Checks. The 2025 and 2024 market totals match the department’s premium distribution reports for those years to the dollar. 8 of the ten have their own page in the department’s Top 25 groups report; for 7 of them the workers’ compensation premium there matches the detail file to the dollar, and for Travelers Group it differs by $424,707. We use the detail file, whose total matches the department’s premium distribution report. Shares are our calculation, rounded to 0.01 percentage point.
- Change vs 2024. Uses the same group code in the department’s 2024 report (revised September 2025). If insurers moved between groups, the change reflects that, not only new or lost business.
- What we don’t reproduce. Only the top ten. Loss data, insurer-level detail and the full report are on the department’s site.
Sources
- California Department of Insurance, Rate Specialist Bureau, 2025 California Property & Casualty Market Share Report: detail file MktShrDataPC2025.xlsx (sheet “All Individual Lines”), PrmLssDist2025.pdf and Top25grps2025.pdf. Retrieved October 14, 2026.
- 2024 figures: the department’s 2024 report, detail file MktShrDataPC2024RevSep0825.xlsx and PrmLssDist2024.pdf.
The department’s site policy treats its content as public domain unless otherwise indicated. The report notes “Source: NAIC Database”; we publish only factual figures from the department’s report, with citation. Lapidar is not affiliated with the California Department of Insurance. Check the source before relying on a figure.