What Is an Independent Medical Review (IMR)?
Learn what an independent medical review is, when you can request one, how the IMR process works, and how it can overturn your insurance company's denial.
What Is an Independent Medical Review (IMR)?
An Independent Medical Review (IMR) — also called an External Independent Review: Complete Guide" class="auto-link">External Review or Independent External Review — is a process in which a neutral, third-party organization reviews your insurance company's decision to deny, reduce, or terminate a claim. The reviewing organization is independent of both you and your insurer, and its decision is legally binding on the insurer in most states.
IMR is the final step in the standard insurance appeal process. After you have exhausted your insurer's internal appeals, you have the right to request an external review by an IROs) Explained" class="auto-link">Independent Review Organization (IRO).
When Can You Request an Independent Medical Review?
You can generally request an IMR when:
- Your insurer has denied a claim on medical necessity grounds
- Your insurer denied a claim as experimental or investigational
- Your insurer has denied coverage for a course of treatment or continued hospitalization
- You have completed the internal appeals process and the denial was upheld
- You need an expedited review due to urgent or ongoing medical circumstances
Under the Affordable Care Act (ACA), all ACA-compliant health plans must provide access to independent external review. ERISA-governed employer-sponsored plans that are self-funded are not subject to state IMR laws but are covered under federal external review rules through the Department of Labor.
How Does the IMR Process Work?
Step 1: Exhaust internal appeals. You must generally complete your insurer's internal appeal process before requesting an IMR. However, if your insurer waives this requirement or fails to meet required timelines, you may request an IMR immediately.
Step 2: Request an external review. Submit a written request for external review to your insurer or directly to your state's department of insurance, depending on your state's rules. You typically have 120 to 180 days from the date of the denial notice to file (4 months under federal rules).
Step 3: The insurer assigns an IRO. Your insurer must select an accredited Independent Review Organization from a rotating list. The IRO must be independent — it cannot have a financial relationship with your insurer that would create a conflict of interest.
Step 4: The IRO reviews your case. The IRO assigns a physician reviewer with relevant clinical expertise. The reviewer examines your medical records, the insurer's denial rationale, applicable clinical guidelines, and peer-reviewed literature. You and your insurer may submit additional documentation.
Step 5: The IRO issues a decision. Standard external reviews: Decision within 45 days of the request. Expedited external reviews (urgent/ongoing care): Decision within 72 hours.
Step 6: The decision is binding. If the IRO overturns the insurer's denial, your insurer must cover the claim. The insurer cannot appeal an IRO decision in most cases.
ClaimBack generates a professional appeal letter in 3 minutes — citing real insurance regulations for your country. Get your free analysis →
What Is the IMR Approval Rate?
Studies and state reports consistently show that independent external reviews overturn insurer decisions at a significant rate. In states with published data, overturning rates for medical necessity denials often range from 30% to 60%. In California, where IMR data is publicly reported, the independent medical review process overturns insurer decisions in favor of patients in the majority of cases.
This means that if your internal appeal was denied, an independent review still offers a meaningful chance of getting your coverage approved.
What Types of Denials Can an IMR Review?
IMR can review:
- Medical necessity denials: The insurer said your treatment was not medically necessary
- Experimental/investigational denials: The insurer said the treatment is not proven or FDA-approved
- Level-of-care denials: The insurer said you did not need inpatient or a particular level of care
- Rescission denials: The insurer cancelled your coverage
- Timeliness violations: The insurer failed to make decisions within required timeframes
Most external reviews do not cover administrative denials (such as coverage eligibility disputes, billing errors, or out-of-network disputes governed by the No Surprises Act), which have separate appeal processes.
What Should You Include in an IMR Request?
To strengthen your external review:
- A detailed letter from your treating physician explaining medical necessity
- Copies of relevant medical records, test results, and treatment plans
- Peer-reviewed studies or clinical guidelines supporting the treatment
- A written explanation of why the insurer's denial criteria were incorrectly applied
- Copies of your insurer's denial letters and EOBs
- Your insurance policy and certificate of coverage
The more clinical evidence you submit, the stronger your case. IRO reviewers are physicians who respond to clinical arguments supported by evidence.
Is an IMR the Same in Every State?
No. While federal rules establish a floor, states have their own external review laws that may be more protective. For example, California's IMR process applies to a broader range of denials and has some of the highest published overturn rates. Some states use a centralized state-run process; others allow insurers to contract with accredited IROs directly.
If your plan is a self-funded ERISA plan, state IMR laws do not apply — federal rules govern the process instead.
Fight Back With ClaimBack
If your insurer has denied your internal appeal, an independent medical review is your next powerful step. ClaimBack helps you prepare a compelling case with the clinical evidence and appeal documentation that IRO reviewers look for.
Start your appeal at https://claimback.app/appeal.
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