Utilization review, usually called UR, is the process a California workers' compensation claims administrator uses to decide whether treatment requested by an injured worker's physician is medically necessary. If UR modifies or denies the request on medical-necessity grounds, the worker can generally challenge that decision through independent medical review, or IMR.
The two processes are connected, but they are not the same. UR is the first review of the doctor's treatment request. IMR is the separate appeal process for an eligible UR denial or modification. Both can involve short deadlines, so a worker who receives a UR letter should read the entire notice promptly rather than waiting for the next medical appointment.
California's revised UR regulations took effect April 1, 2026. The applicable rule and deadline can depend on the treatment, whether the request is complete, whether the claim is accepted, and what the notice says.
California employers must provide medical treatment that is reasonably required to cure or relieve the effects of a work injury. In a typical California workers' compensation claim, the treating physician documents the proposed care and sends a Request for Authorization, commonly called an RFA, to the claims administrator.
UR evaluates the medical necessity of that requested care. It may address treatment such as physical therapy, diagnostic imaging, medication, injections, surgery, medical equipment, or a specialist referral. The reviewer generally considers the medical record and California's Medical Treatment Utilization Schedule, or MTUS, which contains evidence-based treatment guidelines.
A UR decision can:
A modification is not the same as a full approval. If a doctor requests twelve therapy sessions and UR authorizes six, the remaining six have been modified or denied and may be part of an IMR request.
The treating physician, not the injured worker, normally starts the authorization process by submitting a complete RFA for a specific course of treatment. California's 2026 regulations standardize the form and the way receipt is measured. A request can be returned as incomplete if required information is missing. Under the current rules, the claims administrator must either accept an incomplete request as complete or return it to the physician with the reasons no later than five business days after receipt.
Medical support matters. A useful RFA should identify the requested treatment, connect it to the work injury, explain why it is needed, and address the relevant MTUS guidance. If the request falls outside the usual guideline, the physician may need to explain why the worker's circumstances support a different approach. A denial caused by missing records or thin reasoning may be harder to reverse unless the missing medical information reaches the proper reviewer on time.
Treatment access can also depend on where the worker receives care. LTHZ Law's guide to medical provider networks in workers' compensation explains how an MPN can affect doctor selection. An MPN issue and a UR issue can occur in the same claim, but one concerns access to providers while the other concerns the medical necessity of requested treatment.
For a complete prospective or concurrent treatment request, California's current regulations generally require a UR decision within a period appropriate to the worker's condition and no later than five business days after receipt. The first day in the count is generally the first normal business or working day after receipt of the completed request.
An expedited request generally must be decided within 72 hours after receipt of the written information reasonably necessary to make the decision. The requesting physician must document why the worker faces an imminent and serious threat to health or why the regular timeframe would be detrimental. Simply labeling a request urgent may not be enough.
Retrospective review, which evaluates treatment already provided, generally has a 30-day decision period after receipt of the request and sufficient information. Drug-formulary disputes have their own rules. Extensions, deferrals, receipt rules, and incomplete requests can alter the practical timeline, so the dates and stated reason in the actual notice should be checked carefully.
The California UR timeframe regulation contains the current five-business-day, 72-hour, and 30-day standards. The rules were reorganized in 2026, so older articles and forms may point to prior section numbers.
Do not rely only on the word "denied." Read the full determination and compare it with the RFA. Important questions include:
A clerical problem is different from a medical disagreement. If UR reviewed a different treatment than the doctor requested, omitted material records, or contains a clear factual mistake, the physician and claims administrator may need to address that problem immediately. Still, informal calls do not necessarily stop an IMR deadline.
IMR is the administrative process used to resolve an eligible medical-necessity dispute after UR modifies or denies treatment. The California Division of Workers' Compensation assigns the case to an independent medical review organization. A physician reviewer examines the relevant records, the UR decision, the treating physician's support, applicable treatment guidelines, and other permitted medical evidence.
IMR is not a new examination of the injured worker. It is generally a records-based review. It also is not the same as a qualified medical evaluation. A QME can address issues such as injury causation, disability, apportionment, work restrictions, or whether a condition has reached maximum medical improvement. The QME process in California serves a different role and normally is not the appeal route for a UR medical-necessity decision.
IMR is also different from disputing whether the employer is legally responsible for the injury or body part. If the claims administrator disputes liability for the treatment for a reason other than medical necessity, the dispute may need to be resolved through agreement or the Workers' Compensation Appeals Board before IMR proceeds.
When UR modifies or denies treatment for medical-necessity reasons, the claims administrator should send the worker an IMR application with the decision. California DWC instructs injured workers to include the complete UR determination, sign the application, include any required representative form, and submit the materials according to the instructions. A copy must also be sent to the claims administrator.
The filing deadline is generally:
The deadline is measured from service of the decision, not from the next doctor visit or the day symptoms worsen. The California DWC's IMR instructions tell workers to follow the deadline printed on the application. Labor Code section 4610.5 also contains exceptions and timing rules, including when required notice was not provided or when another liability dispute delays eligibility. Those exceptions are fact-specific and should not be treated as permission to file late.
A worker can authorize a representative to assist, and the treating physician can provide support. Additional records should be focused and relevant: the RFA, recent reports, imaging or test results, treatment history, prior response to care, and a reasoned explanation of why the requested treatment is medically necessary. More pages are not automatically more persuasive.
Most IMR matters proceed on a regular schedule. An expedited IMR may be available when delay presents an imminent and serious threat to the worker's health. The physician must provide the required certification or supporting statement. Discomfort, inconvenience, or a preferred appointment date may not satisfy that standard.
California law generally calls for a standard IMR determination within 30 days after receipt of the request and supporting documentation. For an eligible expedited review of treatment not yet provided, the statutory period is generally three days after the required application and supporting information are received. Record-submission timing and extraordinary circumstances can affect the overall calendar.
Because the DWC's older IMR FAQ currently warns that it does not yet reflect every regulation effective April 1, 2026, workers should use the current application, current DWC instructions, and the notice issued in their own case.
The IMR determination is generally binding on the parties. If the reviewer finds the treatment medically necessary, the claims administrator ordinarily must authorize treatment that has not yet been provided within five working days after receiving the written decision, or sooner when medically appropriate. If IMR upholds the denial, the requested treatment generally remains unauthorized through workers' compensation.
An IMR determination can be appealed to the WCAB only on limited statutory grounds, not simply because a party disagrees with the medical conclusion. The petition deadline is generally 30 days from mailing of the final determination. Issues such as fraud, conflict of interest, discrimination, plainly erroneous fact, or action beyond the reviewer's authority can require close legal analysis.
A treating physician may sometimes submit a later RFA supported by a documented material change in facts, as allowed by the governing rules. Repeating the same request without new support is not necessarily a fresh path around an unfavorable decision.
Medical treatment is only one category of available benefits. LTHZ Law's overview of California workers' compensation benefits explains how medical care fits alongside temporary disability, permanent disability, and other potential benefits.
No. UR addresses whether a specific treatment request is medically necessary. A claim can be accepted while a particular treatment is modified or denied. Conversely, a claims administrator may dispute liability for the claim or body part separately from medical necessity.
The proper process depends on why treatment is disputed. A medical-necessity decision on a treating physician's RFA generally belongs in UR. A dispute about liability, causation, provider status, or an incomplete request may follow different rules. The wording of the notice matters.
Not in the ordinary clinical sense. IMR is an administrative, records-based review by an independent physician reviewer. The reviewer decides whether the disputed treatment is medically necessary under the governing standards.
Most medical-treatment disputes have a 30-day IMR request deadline after service of the UR decision. MTUS drug-formulary disputes generally have a 10-day deadline. Read the application and notice immediately because service rules and limited exceptions can affect the calculation.
Generally, IMR is the process for reviewing a UR medical-necessity decision. A QME addresses other medical-legal disputes and does not replace a timely IMR application.
Late or procedurally defective UR can create legal issues, but the remedy depends on the facts, applicable law, and current case authority. A worker should preserve the RFA, transmission proof, UR letter, envelopes or electronic notices, and all dates, then seek advice promptly rather than assuming treatment is automatically authorized.
The employer or claims administrator bears the cost of the state IMR process. The injured worker does not pay the IMR organization's review fee.
A treatment dispute can turn on a short deadline, the wording of an RFA, missing medical support, or whether the disagreement is truly about medical necessity. Keeping the RFA, UR determination, proof of service, IMR form, medical reports, and correspondence together can make the problem easier to evaluate.
If treatment in your California workers' compensation case was delayed, modified, or denied, contact LTHZ Law for a free consultation. An attorney can review the notices, identify the correct dispute process, and explain the next steps that may be available.
This article is for general informational purposes only and is not legal or medical advice. Workers' compensation procedures and deadlines depend on the facts, the treatment request, the notice, and current law. Reading this article does not create an attorney-client relationship.
