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How Does an IMR Appeal Work for Denied Treatment in California?
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By Eman Yazdchi, Esq. · Certified Specialist in Workers' Compensation Law, State Bar of California Board of Legal Specialization · Cal Bar #285231
An IMR appeal is not a hearing. There is no courtroom, no judge, and no oral testimony. It is a paper review by an independent physician. The reviewer receives your complete file. The reviewer applies the Medical Treatment Utilization Schedule. Then the reviewer issues a written decision that binds the insurer.
The review is fast, free to the worker, and conducted entirely outside the insurer's control. But most IMR reviews uphold the UR denial. The reason is not that the insurer is always right. The reason is not the law. It is that most IMR packets do not address the MTUS criteria the reviewer must apply.
Below: what IMR is. Who conducts it. What the reviewer looks at. How long the process takes. When the narrow WCAB review option applies.
What is Independent Medical Review?
IMR is a records review by an independent physician at Maximus. The reviewer applies MTUS standards and issues a binding written decision.
IMR is the appeal channel created by Labor Code 4610.5 in the 2012 SB 863 reforms. When a UR denial issues, the injured worker or attorney submits an application to the DWC. That application includes the denial letter, the medical record, and the treating physician's RFA. The DWC forwards the file to Maximus Federal Services, an independent organization under contract with the state. Maximus assigns a reviewing physician from a state-supervised roster of specialists.
The insurer pays the IMR fees. The worker pays nothing. The reviewing physician has no relationship with the employer, the insurer, or the treating physician. The IMR decision is sent to the worker, the attorney, and the claims administrator simultaneously.
What does the IMR reviewer actually evaluate?
The reviewer evaluates whether the requested treatment meets MTUS standards. The analysis is based on the worker's specific clinical findings. Insurer preferences and insurer policy play no role.
The reviewer reads the UR denial rationale. The reviewer also reads the treating physician's RFA, the most recent clinical notes, and imaging reports. Supplemental arguments the worker submitted are included too. The reviewer then applies the Medical Treatment Utilization Schedule to the specific facts in the file.
MTUS is the state's official evidence-based treatment standard. For most conditions, MTUS adopts the American College of Occupational and Environmental Medicine guidelines with California-specific modifications. A treatment supported by the MTUS recommendation is presumptively medically necessary. A treatment not covered by MTUS requires peer-reviewed literature establishing it as reasonable for the specific condition.
Take a restaurant worker who needed a lumbar steroid injection after a heavy-lift injury. Her file showed six weeks of documented conservative care failure. An MRI confirmed a disc herniation at the symptomatic level. The treating physician's note cited the MTUS section for lumbar radiculopathy injection therapy. That specific, grounded file gives the reviewer a clear reason to overturn the UR denial.
How long does the IMR process take?
Standard IMR decisions must issue within 30 days of Maximus receiving the complete file. Expedited IMR, for urgent situations, must issue within three to seven business days.
The clock runs from the date Maximus receives the complete application with all required records. Missing or incomplete records delay the start. The worker should follow up to confirm receipt and completeness. The IMR decision letter arrives by mail to the worker, attorney, and claims administrator. If the decision overturns the denial, the carrier must promptly authorize the treatment.
If the carrier delays scheduling even after an IMR overturn, the worker can file a WCAB petition. A penalty under Labor Code 5814 may apply for unreasonable delay. An IMR overturn does not automatically produce the treatment. It produces authorization, and then the carrier must act on it.
When can an IMR decision be challenged at the WCAB?
The WCAB can review an IMR decision on three narrow grounds. Those grounds are fraud, a direct conflict of interest, and a plain factual error about what the file actually contained.
The WCAB cannot reverse IMR on the medical merits. The reviewing physician's assessment of medical necessity under MTUS is final. What the WCAB can examine is procedural. Three grounds exist for WCAB review of an IMR decision. First is fraud by the reviewer. Second is a direct conflict of interest, such as a financial relationship between the reviewer and a party. Third is a plainly erroneous finding about what documents the reviewer actually had in the file.
Most IMR decisions survive WCAB review because the standard is narrow. Most workers after an IMR uphold are better served by having the treating physician submit a new RFA. A new RFA with stronger documentation is faster and less expensive than WCAB litigation. The WCAB review standard is too narrow for most challenges to succeed.
Injured at work? Call (661) 273-1780
Tap to call →How Yazdchi Law Prepares IMR Applications
IMR preparation starts before the denial. Yazdchi Law works with treating physicians to build the clinical record that makes the reviewer's job straightforward.
The IMR file sent to Maximus is the only thing the reviewer sees. There is no opportunity to supplement mid-review or argue in person. A file that arrives complete, organized, and MTUS-grounded produces better results than one assembled under pressure at the deadline.
Eman Yazdchi is a Certified Specialist in workers' compensation law, certified by the California Board of Legal Specialization, State Bar of California. The firm tracks IMR deadlines across all California WCAB jurisdictions. Yazdchi Law files at every venue from Van Nuys to Long Beach to Pomona to Oxnard.
If you received a UR denial in the past 30 days, call (661) 273-1780. Ask whether your file is ready for IMR.
Frequently Asked Questions
Who conducts the IMR review in California?
Maximus Federal Services conducts IMR under a contract with the California Division of Workers' Compensation. Maximus assigns reviewing physicians from a state-supervised roster of licensed California physicians and surgeons. The reviewing physician is selected based on specialty relevance to the treatment in dispute. The insurer has no role in selecting the reviewer. The worker and attorney also have no direct contact with the reviewer. The review is entirely records-based and conducted through the Maximus system. Maximus is a private company under contract with the California DWC. It operates independently of both the insurer and the worker. The DWC oversees Maximus to maintain the integrity of the review program.
Does the IMR reviewer contact my doctor or talk to me?
No. The IMR review is records-based. The independent reviewer does not interview the worker, call the treating physician, or examine the worker in person. The reviewer reads the file submitted: the RFA, clinical notes, imaging reports, the UR denial, and any supplemental arguments. This is why the quality of the written record determines the outcome. A treating physician whose notes are vague, who does not tie the treatment to MTUS criteria, and who submits no imaging to support the request gives the reviewer nothing to work with. Because the reviewer never talks to the worker or physician, the quality of the written file is everything. Workers who explain their case to their attorney and have that explanation translated into MTUS language in the IMR packet get the best results.
What medical standard does the IMR reviewer apply?
The reviewer applies the Medical Treatment Utilization Schedule, the state's evidence-based treatment guidelines adopted under Labor Code 5307.27. MTUS uses the ACOEM guidelines for most conditions, with California-specific modifications. Treatment supported by MTUS is presumptively medically necessary. Treatment not directly addressed by MTUS requires peer-reviewed evidence demonstrating reasonableness for the specific condition. The reviewer is not applying the insurer's internal criteria or the UR physician's personal opinion. The standard is MTUS, published and accessible to anyone preparing an IMR packet. The MTUS is publicly available at the California DWC website. Workers and attorneys can read the relevant MTUS chapter before preparing the IMR packet to understand exactly what the reviewer will look for.
Can the insurer add records or arguments to the IMR file after the worker submits?
No. The insurer submitted the UR denial when it denied the treatment. The IMR process is the worker's appeal. The worker and attorney submit the application and supporting records. The insurer does not participate in the IMR submission process. The insurer is notified of the IMR decision once it is issued. This is a key feature of the IMR system: the insurer does not get to add arguments or records after the worker has filed the appeal. The review is based on the file the worker constructs. This is an important feature of the IMR process. The insurer already submitted its case when it denied through UR. The IMR is the worker's appeal, and the insurer has no right to supplement or argue against it mid-review.
What are the grounds to challenge an IMR decision at the WCAB?
Three grounds exist for WCAB review of an IMR decision. First: fraud by the reviewing physician. Second: a direct conflict of interest, such as a financial relationship between the reviewer and a party to the dispute. Third: a plainly erroneous express or implied finding of fact not subject to expert medical opinion, which means the reviewer was wrong about what documents were in the file, not wrong about the medicine. These grounds are narrow and rarely satisfied. Most workers after an IMR uphold are better served by having the treating physician submit a new RFA with stronger documentation. Workers should consult with counsel before attempting WCAB review of an IMR decision. Filing a WCAB petition on weak grounds wastes time and money. The three grounds are narrow and have a low success rate even when legitimately invoked.
Can I request IMR if the insurer never did a UR review?
IMR is an appeal of a UR denial. If there was no UR denial, there is nothing for IMR to review. If the insurer is simply not responding to the RFA at all, the remedy is to document the missed UR deadline and pursue the carrier through the WCAB for failing to comply with the UR timing requirements. The Sandhagen decision confirms WCAB jurisdiction over untimely UR. A UR denial that was never issued because the carrier ignored the RFA is a different problem than a UR denial that was issued and is now being appealed. If the insurer simply ignored the RFA and never did UR, the worker can seek emergency relief at the WCAB to compel the carrier to process the RFA. The Sandhagen decision gives WCAB jurisdiction over untimely UR decisions.
Last reviewed by Eman Yazdchi, Esq., July 2026.
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