Quick answer: We analyzed every WCIRB experience-modification publication we tracked over 12 months (Aug 2025–Aug 2026) — 10,583 California employers — alongside the full CSLB Master License File (243,636 licenses). Among debit-rated employers (x‑mod ≥ 1.00), the median 2026 mod is 1.29, 64% got worse again this year (median move: +9 points), and the sharpest finding is the two-year climb: half of the employers sitting at 1.25+ today were under 1.00 just four years ago. A costly mod isn't born — it's grown, and the window to stop it is the first bad year.
Brokers talk about experience modifications one policy at a time. We wanted to see the whole board: which trades run hot, how fast a clean rating turns expensive, and what the market underneath looks like. This is the first edition of an index we'll update as the data accumulates. Numbers below use the standard decimal form (1.29 = a 29% surcharge on your workers' comp premium).
We isolated the 3,711 employers currently rated 1.25 or higher that have five consecutive rating years on file, and traced their median path backward:
Median experience modification, by rating year, for the 3,711 employers currently at 1.25+ with five consecutive rated years. Source: WCIRB experience-rating publications, Aug 2025–Aug 2026.
51% of them were under 1.00 four years ago. The median path crosses 1.00 quietly, drifts to 1.14, then jumps 21 points in a single year. The practical read: by the time a mod is obviously bad, three years of claims are already locked into the formula — the intervention point is the first drifting year, not the third. (The mechanics of why are in our X‑Mod guide; what to do mid-spike is in fighting a 2026 mod spike.)
Across 8,580 employers where this year's and last year's mods are both published: 64% deteriorated again, the median change was +9 points, and 39.5% jumped 20 points or more. Mean reversion is not doing the work employers hope it will. The trades that worsened fastest:
| Trade (governing class) | Median 1-yr change | % that got worse |
|---|---|---|
| Concrete & sidewalk work — low wage (5201) | +0.19 | 75.8% |
| Skilled nursing facilities (8829) | +0.17 | 71.4% |
| Plumbing — low wage (5183) | +0.17 | 69.2% |
| Cabinet & fixture installation (5146) | +0.16 | 70.6% |
| Painting — low wage (5474) | +0.15 | 66.7% |
At the other end, trucking firms (7219) and parcel delivery (7198) were essentially flat year-over-year (+0.01 median) — volatile businesses, but not deteriorating as a class in this year's data.
Among the debit-rated population, median 2026 mods by trade (classes with 60+ rated employers in our data):
| Trade (governing class) | Rated employers | Median mod | % at 1.25+ | % at 1.50+ |
|---|---|---|---|---|
| Plumbing — low wage (5183) | 115 | 1.44 | 73% | 42% |
| Tile, stone & terrazzo (5348) | 101 | 1.39 | 75% | 37% |
| Underground conduit & wiring (6325) | 73 | 1.38 | 66% | 41% |
| Door & window installation (5107) | 67 | 1.38 | 76% | 40% |
| Cabinet & fixture installation (5146) | 121 | 1.37 | 67% | 35% |
| Concrete & sidewalk — low wage (5201) | 93 | 1.37 | 70% | 39% |
| Plumbing — high wage (5187) | 216 | 1.36 | 72% | 34% |
| Electrical wiring — high wage (5140) | 146 | 1.35 | 68% | 32% |
| Millwright work (3724) | 170 | 1.35 | 64% | 32% |
| Home care services (8827) | 297 | 1.34 | 59% | 34% |
| Restaurants — fast casual (9083) | 791 | 1.29 | 56% | 32% |
| Roofing — high wage (5553) | 206 | 1.27 | 55% | 28% |
Two patterns stand out. First, the low-wage side of every dual-wage pair runs hotter than its high-wage twin (plumbing 1.44 vs 1.36; painting and electrical show the same gap) — consistent with what dual-wage classification implies about crew experience and turnover. Second, this is not just a construction story: home care, skilled nursing, residential care and restaurants carry construction-grade mods with less of the safety infrastructure the building trades have developed. Class-code mechanics are covered in our WCIRB class-code explainer.
Los Angeles, Orange, Riverside and Ventura counties all post median debit mods of 1.32+, against 1.21–1.24 in Sacramento, Fresno, San Francisco and Santa Clara. Los Angeles County alone accounts for 2,339 of the rated employers in our data — more than the next three counties combined.
Experience ratings only exist for employers above the premium threshold. To see the whole California contractor market, we cross-referenced the complete CSLB Master License File:
Three moves, in order. Pull your WCIRB rating worksheet and check the payroll and claims feeding it — errors compound for three years. Treat your first drifting year as the emergency, not the year you hit 1.35 — the median climb says you have roughly 24 months from "slightly over 1.00" to "priced out of bids." And if you're parked at State Fund with a mod under 1.25, get shopped — the data says a quarter of the market defaults there, and staying is a choice someone should have to justify.
Thrive runs a free X‑Mod review on every California account we quote — worksheet pulled, claims verified, classifications audited, and a realistic read on whether the open market beats your current carrier.
Get your free mod reviewOr call (818) 356-8150.
Experience-modification data: WCIRB experience-rating publications for 10,583 unique California employers, compiled weekly from August 1, 2025 through August 27, 2026 via a commercial monitoring feed; 9,169 employers carry 2026 ratings of 1.00+ and form the debit-rated population analyzed above (the feed is prospecting-oriented and predominantly captures debit-rated employers, so figures describe that population — not the average of all rated California employers, most of whom sit below 1.00). Year-over-year and five-year figures use each employer's own WCIRB-published rating history (8,580 and 3,711 employers respectively); the five-year climb describes employers currently rated 1.25+, i.e., how today's troubled ratings developed — it is not the expected path of any employer crossing 1.00. License-market data: full CSLB Master License File (243,636 records; 232,731 active). Mods are shown in decimal form. First edition; we expect to update this index periodically. Data sources: WCIRB California and the CSLB public data portal.
This study is general information, not insurance or legal advice. Experience ratings and market conditions change; talk with a licensed agent about your specific situation. © 2026 Thrive Risk Management Insurance Solutions, Inc., CA License #6012320. Cite freely with attribution and a link to this page.