What Is California Labor Code §4610.5: Independent Medical Review?

What deadline applies to an IMR request?

Most treatment disputes use a 30-day IMR deadline, while formulary medication disputes can use a shorter 10-day deadline.

For most denied medical treatment, the worker must submit the IMR request within 30 days after service of the UR decision. A drug-formulary dispute can require action within 10 days. If the employer failed to provide the required IMR form and notice, the time-limit issue may need closer review.

The safest practice is to assume the shortest clock may apply until the denial letter is read. Save the envelope, email, portal notice, and the one-page IMR form.

Move fast. The form is short, but the record behind it matters. A same-week review leaves time to fix missing notes.

What does the IMR reviewer decide?

The reviewer decides whether the disputed treatment is medically necessary under California workers' comp treatment standards.

IMR does not decide every claim issue. It usually does not decide injury, earnings, disability rating, or settlement value. It decides the medical-necessity dispute that came from UR. If the carrier is also disputing liability for some other reason, the timing and path can become more complex.

The best evidence is practical: a clear treating-physician report, objective findings, failed conservative care when relevant, imaging, therapy notes, medication history, and a guideline-based explanation for the request.

What happens after IMR overturns a denial?

If IMR overturns the UR denial, the carrier must authorize the treatment covered by the decision.

An IMR decision is binding on the parties for the disputed medical treatment. If the reviewer overturns the denial, the insurer should authorize care promptly. If the reviewer upholds the denial, the worker usually cannot relitigate medical necessity at the WCAB just because the result feels unfair.

There are narrow procedural challenges, but they are not a second medical review. That makes the first IMR submission important.

How can a worker strengthen an IMR packet?

A useful packet is focused, medical, and deadline safe. It connects the requested care to the injury and the treatment guideline.

The treating doctor should explain the diagnosis, current symptoms, objective findings, past care, and why the requested treatment is needed now. The worker should collect missing records quickly and make sure the IMR request names the exact denied service.

A short, organized submission often beats a pile of unrelated records. The reviewer needs a clean path from injury to diagnosis to failed treatment to the requested care.