Utilization review denied my treatment. How does independent medical review work?

When utilization review (UR) finds a requested treatment not medically necessary and denies or changes it, the only way to challenge that decision is independent medical review (IMR) under Labor Code 4610.5. The denial letter must include an Application for Independent Medical Review, DWC Form IMR, filled in except for the worker’s signature. The signed form must be filed within 30 days of service of the UR decision, or 10 days if the dispute is only over a drug on the state formulary’s drug list. A medical reviewer assigned by Maximus Federal Services, the organization the Division of Workers’ Compensation (DWC) has designated for IMR, reviews the records and generally decides within 30 days. The decision binds both sides, and an appeal is allowed only on narrow grounds.

What is utilization review?

Utilization review is the process claims administrators use to decide whether a treatment request from the treating doctor is medically necessary. Requests are measured against the Medical Treatment Utilization Schedule (MTUS), the state’s treatment guidelines, under Labor Code 4610. Every employer must have a UR process, run directly or through its insurer or a contractor (4610(g)).

Anyone handling the claim can approve a request (Fact Sheet A). Only a licensed physician who is competent to evaluate the clinical issues can modify or deny one for medical necessity or for incomplete information (4610(g)(3)(A)). The DWC’s detailed UR and IMR rules are in Title 8 of the California Code of Regulations (8 CCR), sections 9792.6.1 to 9792.15.

How long does UR have to decide?

For treatment not yet given (a prospective review), Labor Code 4610(i)(1) allows up to five normal business days from receipt of the request and the information reasonably needed to decide, and never more than 14 days from the doctor’s recommendation. If the worker faces an imminent and serious threat to health, the limit is 72 hours after the information is received (4610(i)(3)). A review of care already provided has 30 days from receipt of the information reasonably needed to decide (4610(i)(2)).

A denial or modification goes to the requesting doctor within 24 hours of the decision, and in writing to the worker within two normal business days for a prospective review (4610(i)(4)). The letter must give the reasons, the criteria or guidelines used and the clinical reasons for the decision (4610(i)(5)).

What must come with the denial letter?

The Application for Independent Medical Review, DWC Form IMR. Under Labor Code 4610.5(f) and 8 CCR 9792.9.5(e), the claims administrator must complete every field except the worker’s signature and include an addressed envelope. The letter must also say that any dispute goes through independent medical review, within the deadline printed on the form.

If the claims administrator does not send the required form and notice, the time to request IMR does not start until it does (4610.5(h)(3)).

How do I ask for IMR, and how long do I have?

The worker signs the DWC Form IMR and files it, with a copy of the UR decision, within 30 days of service of the written UR decision (8 CCR 9792.10.1). The window is 10 days when the decision only concerns a drug on the MTUS Drug List. Filing can be by mail, fax or electronic transmission, and a copy of the signed form goes to the claims administrator.

The request can come from the worker, the worker’s attorney, or a parent, relative or other designee, and the treating physician may join in and advocate for the worker (Labor Code 4610.5(j); 8 CCR 9792.10.1(c)). The address and fax numbers are on the form and the DWC’s IMR page.

If the claims administrator was also disputing liability for the treatment on other grounds when UR decided, the 30 days run from service of a notice that the other dispute has been resolved (4610.5(h)(2)).

Who decides the IMR, and how fast?

The DWC’s administrative director first checks that the request is eligible: timely, signed, complete, and not tied up in a liability dispute (4610.5(k); DWC IMR FAQ). Maximus then assigns a medical reviewer, who reads the records and does not examine the worker.

Under 8 CCR 9792.10.6(g), as amended operative April 1, 2026, the final determination is due within 30 days of receipt of the application and supporting documents for a regular review. The limits are three days for an expedited review of treatment not yet given and five business days for a dispute only over an MTUS Drug List drug. The administrative director can approve up to three more days in extraordinary circumstances or for good cause.

What happens after the IMR decision?

The determination counts as the administrative director’s decision and binds all parties (Labor Code 4610.6(g); 8 CCR 9792.10.6(h)). If it finds the treatment medically necessary, the claims administrator must authorize it within five working days, or reimburse within 20 days if the care was already given, unless liability is disputed on other grounds (8 CCR 9792.10.7).

If the denial is upheld, the UR decision remains effective for 12 months from its date for the same treatment from the same doctor or practice group, unless a new request shows a documented change in the material facts (Labor Code 4610(k)).

Either side may file a verified appeal with the Workers’ Compensation Appeals Board (WCAB) within 30 days of the date the determination was mailed. The determination is presumed correct and is set aside only on clear and convincing proof of one of five grounds (Labor Code 4610.6(h)):

• The administrative director acted without or beyond its powers.
• Fraud.
• A reviewer’s material conflict of interest.
• Bias based on race, sex, religion, disability or another listed trait.
• A plainly erroneous finding of fact on a matter of ordinary knowledge, not one of professional opinion.

Winning that appeal does not order the treatment. The dispute goes back for a new review by a different IMR organization or reviewer, and no judge may make a finding of medical necessity contrary to the IMR (4610.6(i)).

What are the steps from a treatment request to an IMR decision?

Step	Who acts	Time limit	Rule
Request for authorization, with supporting documents	Treating physician	When treatment is recommended	LC 4610(g)(2)(A)
UR decision on treatment not yet given	Physician reviewer for the claims administrator	5 business days from receipt; never more than 14 days from the recommendation	LC 4610(i)(1)
UR decision when health is under imminent and serious threat	Physician reviewer	72 hours	LC 4610(i)(3)
UR decision on care already given	Physician reviewer	30 days	LC 4610(i)(2)
Written denial to the worker, with DWC Form IMR and envelope	Claims administrator	2 business days after a prospective decision	LC 4610(i)(4)(B), 4610.5(f)
IMR request	Worker, attorney or designee	30 days from service of the UR decision (10 for MTUS Drug List drugs)	LC 4610.5(h); 8 CCR 9792.10.1
IMR determination	Maximus medical reviewer	30 days regular; 3 days expedited; 5 business days for drug list disputes	LC 4610.6(d); 8 CCR 9792.10.6(g)
Treatment authorized after an IMR approval	Claims administrator	5 working days (20 days to reimburse care already given)	LC 4610.6(j); 8 CCR 9792.10.7(a)
Appeal to the WCAB	Either side	30 days from mailing of the determination	LC 4610.6(h)

Sources: Labor Code 4610, 4610.5 and 4610.6; 8 CCR 9792.10.1, 9792.10.6 and 9792.10.7; the DWC IMR FAQ. Read October 8, 2026.

What do people get wrong about UR and IMR?

• Treating a UR denial as a denied claim. UR rules on one treatment request, and the claim itself can still be accepted. A denied claim is a different dispute, covered in my workers’ comp claim was denied.
• Taking a treatment dispute to a QME. The DWC’s FAQ for employees says a qualified medical evaluator may not comment on a request for medical treatment, and Labor Code 4610.5(e) says a UR decision may be reviewed or appealed only by IMR.
• Leaving the form unsigned. Fact Sheet A says the IMR form arrives completed but unsigned and must be signed and sent to start the process. The IMR FAQ adds that a late application cannot be corrected.
• Waiting on an internal UR appeal. The regulations make it voluntary, say it “neither triggers nor bars” IMR, and allow it only after the worker has been told the IMR filing deadline (8 CCR 9792.9.5(e)(13) and 9792.10.1(f)).

What should I read next?

• What a UR denial case involves: utilization review denials.
• Doctors, MPNs and second opinions: medical treatment and MPN doctors.
• When the whole claim is denied: my workers’ comp claim was denied.
• Medical disputes other than treatment: what is a QME exam.

Whether a particular treatment should have been approved is a medical and legal question about one case, and this page does not answer it.

Where does the Law Office of Jesse Melendrez fit?

A treatment denial can sit next to other questions in the same claim, such as whether the body part has been accepted or whether temporary disability continues. For a represented worker, the attorney can file the IMR application (8 CCR 9792.10.1(c)(1)) and track the deadlines that follow.

The Law Office of Jesse Melendrez is in Newport Beach. We limit our practice to California workers’ compensation and represent injured workers only, with cases at the WCAB district offices in Santa Ana, Anaheim, Los Angeles, Riverside and San Diego. Attorney Jesse Melendrez (State Bar of California #263751) has represented injured workers since 2009.

This page explains how UR and IMR work. It is not legal advice about your treatment. If you would like us to look at your UR letter, tell us what happened.