Californians who appeal mental health denials win three times out of four

Quick answer: is appealing a mental health denial worth it?

Yes, and the state's own numbers say so. California's Department of Managed Health Care runs an Independent Medical Review (IMR) program: when your plan denies therapy, residential treatment, testing, or medication as "not medically necessary," an outside physician reviewer looks at your records and decides who is right. The review is free, you can apply after your plan's internal grievance fails, and the decision is binding on the plan. Over the last five full years, reviewers sided with the patient in 1,356 of 1,802 mental health cases: 75.2%.

Lean Medical pulled every behavioral health IMR decision in the state's public file and computed the outcomes. This is what the record shows.

What the data shows

The trend line is the striking part. In 2015, reviewers overturned about half of appealed mental health denials. Every year since 2020, the rate has been 70 percent or higher, and it reached 82.6% in 2025. Across the full 2006-2025 file, 5,890 mental health denials went to review and 3,364 were overturned (57.1%). Mental health cases also win more often than the file as a whole: across every diagnosis category in the same period, the overturn rate is roughly 53 percent.

The jump follows years of state parity enforcement and, from 2021, SB 855, the California law that requires commercial plans to cover medically necessary treatment for all mental health and substance use conditions under generally accepted standards of care. Whatever the exact mix of causes, the practical read is simple: in recent years, when an independent physician examines a mental health denial, the denial usually does not survive.

Outcomes differ by condition. Substance use disorder appeals win more than eight times in ten, and PTSD appeals about seven in ten. Appeals involving depression and anxiety run closer to the middle, and even the lowest-performing common categories still win roughly half the time in recent years. Denials argued as "experimental or investigational" are the hardest to beat; straight medical necessity denials, which are the large majority of mental health cases, overturn at 59.3% across the file.

Autism spectrum cases, mostly disputes over ABA therapy hours and coverage, are tracked as their own category: 1,343 decisions since 2006, 67.6% overturned.

Almost nobody appeals

Set those win rates against how rarely anyone uses the process. KFF's analysis of federal marketplace plans found insurers denied about 20 percent of in-network claims in 2023, and consumers appealed fewer than 1 percent of those denials. When people did appeal to the insurer itself, the insurer upheld its own denial 56 percent of the time. That is the asymmetry worth knowing: internal appeals, judged by the company that issued the denial, mostly fail. Independent review, judged by an outside physician, mostly succeeds, at least for mental health care in California. The 1,802 people who took mental health cases to IMR from 2021 through 2025 are a rounding error against the volume of denials in a state of 39 million people.

How the appeal process actually works

Two steps, in order. First, file a grievance with your health plan; the plan has 30 days to respond (72 hours if urgent). Second, if the plan says no again or misses its deadline, apply to the DMHC for an Independent Medical Review at healthhelp.ca.gov or by phone at 1-888-466-2219. You have six months from the plan's grievance response to apply. There is no cost. Standard reviews are decided in about 45 days, urgent ones in about 7, and if the reviewer sides with you, the plan must promptly cover the care. Most California HMOs and many PPOs are DMHC-regulated; PPOs regulated by the California Department of Insurance have a parallel IMR process with the same shape.

Keep the denial letter, ask your clinician for a letter of medical necessity, and reference the specific care requested. Both the federal Mental Health Parity and Addiction Equity Act and SB 855 require plans to cover mental health care on the same terms as physical care, and IMR reviewers apply those standards. Our guides to verifying your mental health benefits and in-network vs out-of-network therapy cover the vocabulary the paperwork uses.

The easier path is not needing the appeal. Denials cluster around out-of-network claims and care the plan never pre-authorized, so starting with a clinician who is already in-network with your plan removes most of the fight. Lean Medical is in-network with Cigna and Aetna, and you can check your coverage and book online in a few minutes.