Workers’ Comp Treatment Denied in California? Understanding UR and IMR

Read the source decision or official guidance.

A treating physician may recommend surgery, physical therapy, medication, or diagnostic testing for a work injury—only for the claims administrator to deny, delay, or modify the request. When workers’ compensation refuses to authorize requested medical care, navigating the review process and unfamiliar terminology can feel overwhelming.

California generally routes disputes about the medical necessity of requested treatment through utilization review, commonly called UR, followed by Independent Medical Review, or IMR. The process is deadline-sensitive. The reason stated in the decision, the form accompanying it, and the medical records sent for review can all matter.

What is utilization review in California workers’ compensation?

Utilization review is the process an employer or claims administrator uses to determine whether treatment requested by the treating physician is medically necessary. The review must use California’s Medical Treatment Utilization Schedule and comply with Labor Code section 4610 and implementing regulations.

UR is not the same thing as a claims adjuster simply disagreeing with a doctor. California’s system requires medical-necessity decisions to be made within a regulated clinical-review structure. A decision may approve the treatment, approve only part of it, modify it, delay it for permitted reasons, or deny it.

The California Division of Workers’ Compensation adopted revised UR regulations effective April 1, 2026. That makes it especially important to use the current forms and instructions rather than relying on an old online checklist.

What can an injured worker do after a UR denial?

When UR denies or modifies treatment because it is considered medically unnecessary, an injured worker may request IMR. The DWC instructs workers to review the UR letter, sign the current IMR application, attach the complete UR determination, and submit the materials within the deadline printed on the application. Depending on the kind of determination, the form may state a 10-day or 30-day filing period.

Practical steps can include:

• Save the envelope, decision letter, and every attachment.
• Confirm that the letter includes the correct IMR application.
• Compare the treatment requested by the physician with the treatment addressed in the UR decision.
• Ask whether the reviewer had the records explaining why the treatment was requested.
• Calendar the deadline immediately rather than waiting for the next appointment.
• Keep proof of the IMR submission.

If a worker believes the claims administrator did not conduct UR within the required procedure or time, the issue may differ from a medical-necessity disagreement. The correct remedy can depend on why the treatment was not authorized.

What Stevens explains about Independent Medical Review

In Stevens v. Workers’ Compensation Appeals Board, the California Court of Appeal considered constitutional challenges to the IMR system after requested medication and home-health services were denied. The court upheld the statutory IMR framework. It also concluded that the WCAB had misunderstood part of its authority when reviewing whether the IMR determination rested on a plainly erroneous factual mistake.

The decision is important, but it does not mean that every IMR denial is unreviewable. California law identifies limited grounds for appealing an IMR determination to the WCAB, including fraud, a material conflict of interest, specified bias, action beyond the Administrative Director’s authority, or a plainly erroneous mistake of fact that does not involve medical expertise. The final IMR determination is presumed correct, and the WCAB generally cannot substitute its own medical-necessity determination.

Why the medical record matters

IMR is a medical review. A treating physician’s request should explain the diagnosis, prior treatment, response to care, objective findings where applicable, and why the requested service is medically necessary under the relevant guideline or supported exception. Missing records or an incomplete explanation can affect the reviewer’s understanding.

That does not mean an injured worker should alter or manufacture evidence. It means that accuracy and completeness matter. A worker may want to confirm that the treating physician and claims administrator have the same essential records and that the request actually addresses the medical issue in dispute.

What happens after IMR?

The independent reviewer may uphold or overturn the UR determination. If the treatment denial is overturned, California law governs implementation of the decision. If the denial is upheld, an appeal to the WCAB is limited and subject to a short deadline; it is not a new hearing at which a judge simply chooses a different medical opinion.

Other disputes—such as whether the injury is industrial, whether the employer is liable for the claim, or whether UR was timely—may follow different procedures. That is why the precise language in the notice matters.

Key takeaways

• A UR denial is not necessarily the end of a treatment request.
• IMR deadlines can be short, so read the current form immediately.
• The treating physician’s explanation and supporting records can be critical.
• Appeals from IMR are available only on limited statutory grounds.
• California’s UR regulations changed on April 1, 2026; current guidance should control.

If your workers’ compensation doctor requested treatment and the request was denied or modified, counsel can help identify the type of dispute, preserve the applicable deadline, and evaluate the record. Call Mission X Trial Lawyers at (949) 343-9735 or email office@mcxlegal.com to discuss your situation.