California IMR Overturn Rate Tracker

A decade of Independent Medical Review outcomes in California workers' compensation. Updated annually when the Division of Workers' Compensation releases its IMR Report. Current through the 2026 report analyzing 2025 data, released May 19, 2026.

The headline: only about 1 in 10 denied treatments gets overturned — and it has been that way for ten years. In 2025, IMR issued 152,351 determinations and upheld the payer's denial in 89.8% of them. Across 2016–2025 the overturn rate has never exceeded 12.7% and never fallen below 7.2%.

Reuse this data. These figures are drawn from public DWC reports. Charts, tables, and figures on this page may be reproduced freely with attribution to Solov & Teitell and a link back. If you are a journalist, researcher, union representative, or treating physician and want the underlying extraction, contact us.

Why this page exists

California publishes IMR outcome data every year in a PDF. Insurance trade publications cover it. Applicants' attorneys read it. Almost nobody assembles it into a form an injured worker, a treating physician, or a reporter can actually use — and nobody tracks it across time in one place.

So we do. Once a year, at a stable URL, with sources on every figure.

Determinations and outcomes by year

Ten-year totals: 2,082,085 applications. Best year for injured workers: 2024, at 12.7% overturned. Worst: 2021, at 7.2%.

Two things stand out. Application volume fell roughly a third — 32% — from its 2018 peak of 252,565 to a 2021–2023 trough, then climbed back above 200,000 in 2025. And the outcome rate is remarkably stable — a ten-year band of 5.5 percentage points, through a pandemic, a formulary rollout, and multiple regulatory overhauls.

2025 detail. 152,351 determinations issued — 152,243 standard and 108 expedited. Expedited review was 0.07% of all determinations. Duplicate applications were 16.6% of filings. Ineligible applications fell 7.9% from 2024, while untimely filings rose 5.4%. Average turnaround: 6–7 days from receipt of complete records; 25 days from assignment; 2 days for expedited. 99.99% of standard determinations issued within the 30-day statutory deadline — only 13 cases statewide exceeded it.

Outcomes by treatment category, 2025

Based on 266,756 disputed treatment requests. (Requests exceed determinations because one IMR can cover several requested services.)

Pharmaceuticals and rehabilitation together account for 53.5% of every disputed treatment request in California, and both sit near a 9% overturn rate.

The categories with the best odds — programs, behavioral health, evaluation and management — are collectively under 8% of volume. The disputes that happen most often are the disputes injured workers are least likely to win.

A note on injections. Effective April 1, 2026, spinal injections were added to the list of treatments requiring prospective utilization review even during the first 30 days after injury (8 CCR § 9792.9.7(b)(8)). That is a category with a 93.3% uphold rate. More injection requests will now route through UR, and the historical odds on them at IMR are among the worst in the system. We will track whether the 2026 data reflects it.

Pharmaceutical outcomes by drug class, 2025

Muscle relaxant denials are upheld 98.6% of the time. Antidepressants, at 24.1% overturned, are more than seventeen times likelier to be reversed.

Trend: pharmaceuticals fell from 32.7% of all disputed requests in 2024 to 30.6% in 2025. Opioids fell from 24% to 22% of pharmaceutical requests.

Who decides

85% of 2025 cases were handled by California-licensed reviewers; 77% of decisions came from board-certified specialists in occupational medicine, orthopedic surgery, pain medicine, or physical medicine and rehabilitation.

Reviewer identities are confidential under Labor Code § 4610.6(f). Neither the injured worker, the treating physician, nor the employer learns who decided the case.

Who is requesting

The DWC report does not publish physician-concentration data. These figures come from the California Workers' Compensation Institute, an insurer-funded research organization — we cite the source because the framing is not neutral even though the finding is real.

Seven of the top ten in the 2025 period repeated from the prior year.

Roughly 80 physicians generate more than four of every ten disputed treatment requests in California. Both sides of the system cite this number and draw opposite conclusions. The payer reading is that a small group of outlier prescribers drives system cost. The applicant reading is that a small group of physicians is still willing to request care that most have stopped requesting, because the odds are nine to one against and the paperwork is unpaid. The data supports both readings; it settles neither.

What the numbers do and do not mean

They do not mean IMR is pointless. You must file. It is the exclusive route to challenge medical necessity, and not filing forfeits the issue entirely.

They do not mean 90% of denials are correct. They mean 90% are upheld by a paper review against guidelines that carry a statutory presumption of correctness. Those are different claims, and the data cannot distinguish them.

They do mean the leverage is usually somewhere else. Because the medical question is effectively unappealable — a successful WCAB appeal under Labor Code § 4610.6(h) produces, under § 4610.6(i), a second IMR by a different review organization rather than a treatment authorization — the productive fight in most denied-treatment cases is over whether the underlying utilization review was timely and procedurally valid. Under Dubon II, invalid UR sends medical necessity to a judge instead of to IMR. That is a question the data above says nothing about, and it is the question worth asking first.

They also mean the category matters. A worker appealing a denied functional restoration program is in a materially different position than one appealing a muscle relaxant. Knowing which you are is worth the two minutes it takes to check.

Sources and method

All primary figures are drawn from the DWC's annual IMR reports. Determination counts, eligibility figures, category breakdowns, drug-class breakdowns, and reviewer specialty data for 2025 come from the 2026 IMR Report: Analysis of 2025 Data (data extraction date March 5, 2026; released May 19, 2026 per DWC Newsline 2026-43). Year-over-year figures for 2016–2024 come from that report's trend tables.

Two limitations we will not paper over.

Figures for 2013–2015 — IMR's first three years — are not included, because the current DWC report's trend table begins at 2016 and we have not independently verified the archived reports. We would rather show a ten-year series we can stand behind than a thirteen-year one we cannot.

CWCI's series counts determination letters; DWC counts applications and final determinations. The two are not directly comparable and we do not mix them in a single table.

One trap worth flagging for anyone else working with this data. The California Health & Human Services open data portal hosts a dataset titled "Independent Medical Review (IMR) Determinations, Trend" covering 2001 to present. That is the Department of Managed Health Care's IMR program for commercial health plans — a different statutory scheme entirely. It is not workers' compensation data, and it is frequently miscited as such.

Next update

May 2027, on release of the DWC 2027 IMR Report covering 2026 data. That report will be the first to reflect a full year under the utilization review regulations that took effect April 1, 2026 — including the 30-day no-prior-authorization window, the non-extendable five-day formulary clock, and the addition of spinal injections to the mandatory prospective-review list. We will publish the comparison.

Compiled and reviewed by Jamey Teitell, Partner and Trial Attorney, Law Offices of Solov & Teitell, APC. California State Bar #183718. Last updated August 19, 2026.

Related: Utilization Review — every deadline and what makes a denial invalid · Independent Medical Review — the process end to end

If a treatment you need was denied on independent medical review, the numbers on this page are the reason not to stop there. The overturn rate is low precisely because most requests are never developed properly before they go in — and because the thirty-day window to request review closes quietly.