In this guide7 sections
California’s Independent Medical Review (IMR) system upheld insurers’ treatment denials even more often in 2025 than the year before. According to the Division of Workers’ Compensation’s 2026 IMR report, reviewers overturned only 10.2% of utilization review decisions in 2025, down from 12.7% in 2024. If your doctor’s treatment request is denied or cut back, you still have options, but the deadlines are short and the way you build the record matters.
Key takeaways
- In 2025, IMR upheld 89.8% of the utilization review (UR) decisions it reviewed, up from 87.3% in 2024.
- You generally have 30 days after the UR decision is served to request IMR, or 10 days for drug formulary disputes (Labor Code §4610.5(h)).
- IMR is paid for by the employer; you file a one-page application that comes with the denial letter.
- An untimely UR decision is invalid, and the Workers’ Compensation Appeals Board (WCAB) can then decide whether the treatment is medically necessary.
- IMR decisions can be appealed only on narrow grounds, within 30 days of mailing (Labor Code §4610.6(h)).
What the 2025 numbers show
The DWC’s report analyzing 2025 data found:
| Measure | 2025 |
|---|---|
| IMR applications received | 201,037 |
| Final IMR decision letters issued | 152,351 (up 7.6% from 2024) |
| UR decisions overturned | 10.2% (12.7% in 2024) |
| UR decisions upheld | 89.8% (87.3% in 2024) |
| Share of disputes involving prescription drugs | 30.6% |
Overturn rates varied by type of care. The highest were for treatment programs (18.5%), behavioral and mental health care (18.3%) and evaluation and management visits (16.8%). The lowest included injections (6.7%) and transportation (3.6%).
Once a dispute reaches IMR, the odds favor the denial. Your strongest chances often come earlier, with a well-supported treatment request, and in spotting procedural defects in the UR decision.
How utilization review works
Every employer must have a UR program to review your doctor’s treatment requests (Labor Code §4610). Key rules:
- Deadlines. A prospective decision is due within five normal business days of receiving the request, and never more than 14 days from the doctor’s recommendation. Urgent requests must be decided within 72 hours.
- Who can deny. Only a licensed physician competent to evaluate the clinical issue may modify or deny treatment for medical necessity reasons.
- Written notice. Denials and modifications must be sent to you in writing, along with an IMR application form and envelope.
- The guidelines. UR and IMR apply the Medical Treatment Utilization Schedule (MTUS).
For more detail, see what utilization review is and our Labor Code §4610 guide.
How to request IMR
- Check the deadline printed on your application. It is usually 30 days from service of the UR decision, or 10 days for formulary drug disputes.
- Complete and sign the IMR application (form DWC IMR-1) and attach a copy of the full UR decision. The DWC’s IMR page has the form and mailing instructions.
- Send supporting records. You and your treating doctor can submit information showing why the treatment is medically necessary.
- Watch for the decision. Standard reviews are decided within 30 days of receiving the request and records, with faster timelines for urgent cases.
If your claim’s liability is disputed, IMR generally isn’t available until that issue is resolved. Learn more in what an IMR is.
Ways to challenge a denial
- Look for an untimely UR decision. The WCAB has held that an untimely UR decision is invalid and not subject to IMR, and the WCAB may then decide medical necessity itself. Other UR disputes must go through IMR.
- Strengthen the next request. A request that explains your functional limits, failed prior treatments and how the care fits the MTUS gives the reviewer more to work with.
- Appeal on the limited grounds allowed. An IMR decision is presumed correct and can be set aside only for reasons such as fraud, a reviewer’s material conflict of interest, bias, acting beyond legal authority, or a plainly wrong finding of fact that is a matter of ordinary knowledge. The appeal must be filed within 30 days of the decision’s mailing.
Example (hypothetical): Carlos’s doctor requests 12 physical therapy sessions after a shoulder surgery. The UR denial arrives three weeks after the request. Because the decision may have been untimely, Carlos’s attorney can ask the WCAB to decide the request instead of going through IMR.
Frequently asked questions
Do I have to pay for IMR?
No. The DWC says employers pay the costs of IMR.
What if I miss the IMR deadline?
The UR decision generally becomes final for that request. Your doctor may be able to submit a new request if your condition or the supporting facts change, so talk to your doctor or a lawyer quickly.
Can the WCAB judge overrule an IMR decision?
Not on medical necessity. If an appeal succeeds, the dispute goes back for a new IMR with a different reviewer; a judge can’t substitute a contrary medical necessity decision.
Is IMR the same as a QME?
No. IMR resolves treatment disputes; a QME evaluates broader medical issues such as disability and work restrictions. See the difference between IMR and a QME.
Talk to a California workers’ comp lawyer
Employees First Labor Law represents workers exclusively, including injured workers in workers’ comp cases. If your treatment was denied or delayed, we offer free virtual consultations to review your UR and IMR letters. Contact us or call (310) 853-3461.
This article is general information about California law as of 2026, not legal advice for your situation. Reading it does not create an attorney-client relationship.
