External review in California: the Independent Medical Review (IMR)

How IMR works — and which agency runs yours

California's external review is the Independent Medical Review (IMR). Two state agencies run it depending on the plan, and an independent physician outside the plan reviews the case. IMR is for denials that turn on medical judgment — medical necessity, the right level of care, and experimental or investigational determinations — not a flat contractual exclusion the plan simply doesn't cover.

• HMO or managed-care plan → the Department of Managed Health Care (DMHC), which regulates most insured Californians. Help Center: 1-888-466-2219.
• PPO or indemnity insurance → the California Department of Insurance (CDI).
• Not sure which? The DMHC Help Center will tell you which agency your plan falls under.

The six-month deadline — longer than the federal standard

You generally have six months from the date the plan upholds its denial through its internal grievance process to request an IMR — notably longer than the federal four-month external-review window. It's a real advantage, but the clock runs from the final internal decision, so building the request while the record is fresh is still the stronger play.

Most cases require you to finish the plan's internal grievance first. There are exceptions: for an imminent and serious threat to health, or for certain experimental/investigational-treatment denials, you can apply for an IMR without completing the internal process.

How to request an IMR

1. 1

   Finish the internal grievance (usually)

   Complete the plan's internal appeal first — unless the case is urgent or involves an experimental/investigational-treatment denial, which can go straight to IMR.

2. 2

   File the IMR/Complaint form

   Online is fastest and the DMHC encourages it; you can also mail or fax the form to the Department of Managed Health Care, 980 9th Street, Suite 500, Sacramento, CA 95814.

3. 3

   Attach the denial and the record

   Include the plan's denial letter and the clinical documentation supporting medical necessity — the reviewer decides on the record in front of them.

4. 4

   Get help at no cost

   The DMHC Help Center (1-888-466-2219) walks consumers and providers through the process for free.

How fast — and it costs nothing

• Standard IMR: a decision generally within 45 days.
• Expedited IMR: within about 7 days when there's an imminent, serious threat to health — severe pain, or risk to life or the ability to regain function.
• The IMR is free to the patient.
• The decision binds the plan: if the IMR overturns the denial, the plan must authorize the service or pay the claim.

What actually gets overturned in California

California publishes every IMR decision, which makes it one of the few places you can see what independent reviewers actually do — and the odds swing enormously with what's being denied. Across the high-volume categories we analyzed in the state's published determinations, viscosupplementation (knee-injection) denials were overturned in roughly nine of ten IMRs; weight-control/bariatric-related and residential behavioral-health denials in the low-to-mid 80s percent; biologic drugs near four in five. Routine imaging (MRI) and lab-work denials, by contrast, landed closer to half or were upheld more often — the plan's criteria hold up more of the time there.

For California providers and billers

Two things make California distinctive for a practice. First, SB 1120 (2024) — the Physicians Make Decisions Act — bars payers from letting artificial intelligence or an algorithm alone deny a claim on medical necessity; a licensed clinician must make that call. That gives an appeal real leverage when a denial looks automated. Second, the free, binding IMR — with published outcomes — means a clean internal appeal that sets up the IMR is worth building, not writing off.