Health insurance claim denial appeal — medical bill and appeal letter illustration

Health Insurance Claim Denied for Non-Covered Services 2026: IRO Appeals and State Remedies

Daylongs · May 14, 2026 · 16 min read

#health insurance #claim denial #non-covered services #IRO #independent review #insurance appeal #insurance

The Denial Letter Is Not the Final Answer

Health insurers deny claims for a range of reasons, some legitimate, some contestable. The critical misunderstanding most patients have is that a denial letter is a final decision. It is not — it is the opening of a dispute process that, if properly pursued, reverses the denial in a meaningful percentage of cases.

The federal Affordable Care Act guarantees the right to appeal health plan denials, including the right to independent review by an external organization that is not paid by your insurer. Most patients never use this right. Those who do often recover substantial reimbursements.

ACA external review information: healthcare.gov | State insurance commissioner directory: naic.org

Why Non-Covered Service Denials Are Different from Other Denials

Denials fall into two broad categories: procedural (you needed prior authorization, used an out-of-network provider) and substantive (the service itself is not covered or not medically necessary). Non-covered service denials are substantive and harder to reverse — but not impossible.

The distinction that matters:

Categorical exclusion (“this service is not in the plan”): appeals rely on arguing that the service should be classified differently, or that coverage applies by virtue of another provision
Medical necessity denial (“this service is not medically necessary for your condition”): appeals rely on clinical evidence that the service is necessary, supported by your physician and published guidelines
Experimental/investigational (“this treatment is not proven”): the strongest ground for IRO appeal based on clinical literature

How to Read Your Denial Letter and EOB

Your Explanation of Benefits (EOB) contains a reason code for the denial. Before appealing, identify the exact reason — it determines your strategy.

Common denial reason codes and what they mean:

Code Type	Meaning	Appeal Strategy
Not medically necessary	Insurer’s reviewer determined no clinical need	Physician letter, clinical guidelines, peer literature
Service not covered	Categorical exclusion in your plan	Argue service category, read plan language carefully
Experimental/investigational	Treatment not proven effective	IRO is most effective route; submit clinical literature
Authorization not obtained	Prior authorization was required but not requested	May be procedurally barred; check network agreement
Out-of-network provider	Provider not in plan network	Check No Surprises Act applicability; prior approval

The Internal Appeal: What to Include

An internal appeal is your first required step. Make it count — the record you build here becomes the foundation for an IRO review.

Elements of an effective internal appeal:

Copy of the denial letter and EOB — reference the specific reason code
Physician’s letter of medical necessity — must be specific to your condition, not boilerplate; ideally signed by a specialist
Clinical guidelines — NCCN guidelines (for cancer), professional society recommendations, or other authoritative clinical standards that endorse the treatment
Peer-reviewed literature — published studies showing effectiveness for your specific diagnosis
Your insurer’s own criteria — many insurers publish their coverage determination guidelines; if the insurer’s own criteria supports the service, cite it directly

Format matters: Structure the appeal as a logical argument. Address each denial reason with corresponding evidence. A disorganized appeal is harder for reviewers to rule on favorably.

External Review: The IRO Process

After an internal appeal is denied (or if the insurer fails to act timely), you may request external review.

What the IRO does:

Assigns board-certified physician reviewers who specialize in the relevant medical area
Reviews all submitted materials — both yours and the insurer’s
Issues a decision that is binding on the insurer under most state and federal law

How to request:

Non-ERISA plans (individual market, state-regulated): contact your state insurance commissioner
ERISA plans (most employer-sponsored plans): the federal external review process through your plan’s administrator or through a federally-contracted IRO list available at healthcare.gov

Timeframes:

Standard review: within 45 days of request
Expedited review (urgent medical situations): within 72 hours

Worked Scenarios

Scenario A: MRI Denied as Not Medically Necessary

Patient with persistent lower back pain; orthopedic specialist orders MRI
Insurer denies: “Criteria for MRI not met — conservative treatment not exhausted”
Patient had received 6 weeks of physical therapy with no improvement

Internal appeal:

Orthopedic surgeon documents 6-week PT course and continuing dysfunction
Includes American College of Radiology appropriateness criteria for lumbar MRI in patients with failed conservative treatment
Cites insurer’s own published coverage criteria, which allow MRI after 6 weeks of failed conservative care

Outcome: Internal appeal approved; MRI covered. Total cost at stake: approximately $1,200–$2,500 depending on region.

Scenario B: Cancer Treatment Denied as Experimental

Patient with stage III ovarian cancer; oncologist recommends PARP inhibitor maintenance therapy
Insurer denies: “Treatment considered investigational for this indication”
FDA approved the drug for this indication in a prior year

IRO appeal:

Oncologist submits FDA approval documentation for the specific indication
Includes NCCN guidelines listing the drug as a category 1 recommendation
IRO overturns denial; insurer required to cover
Cost of drug: approximately $12,000–$18,000/month — a significant recovery

What the Industry Relies On That You Should Know

Insurance company medical directors who deny claims often do so based on criteria the insurer developed internally — criteria that do not always match published clinical standards. The IRO process directly addresses this by substituting an independent physician’s assessment.

The conventional advice from patient advocacy groups is “just file the appeal.” The better advice is: file a targeted appeal that directly contradicts the insurer’s stated reason using language and evidence the IRO reviewer — a specialist physician — will find credible. A generic letter saying “this treatment is important to me” loses. A letter with clinical guideline citations, peer literature, and FDA approval documentation wins far more often.

State Insurance Commissioner Complaints

If the insurer is not following required appeal procedures, delaying responses beyond required timeframes, or engaging in bad-faith claims handling, a state insurance commissioner complaint is an additional tool.

Find your state’s commissioner: naic.org (National Association of Insurance Commissioners)

Commissioner complaints:

Create a regulatory record
Prompt the insurer to review the file more carefully
Can result in formal regulatory action for repeated violations

The Industry Logic That Works Against Patients

Health insurers use algorithms and internal clinical criteria to adjudicate claims. Understanding how these systems work gives you a strategic advantage when appealing.

Most large commercial insurers — Aetna, Cigna, UnitedHealth, Anthem — maintain their own coverage determination policies (sometimes called medical policies or clinical guidelines). These policies define what the insurer considers medically necessary for each service. They are distinct from, and sometimes more restrictive than, published evidence-based guidelines.

The key asymmetry: The insurer’s internal reviewer who denied your claim may be a registered nurse or physician using criteria written by the insurer’s medical management department — criteria designed to reduce claim payments. The IRO physician who reviews an external appeal is a board-certified specialist in the relevant field, applying current clinical evidence.

This is why external IRO review reversal rates are meaningful: the IRO reviewer is not constrained by the insurer’s proprietary criteria. They apply clinical evidence and specialty standards directly.

Practical implication: When building your appeal, do not try to satisfy the insurer’s internal criteria (which you may not have full access to). Instead, make the clinical case that any competent specialist would find compelling — the IRO reviewer will apply that standard.

How Prior Authorization Failures Create Denial Risk

Prior authorization (PA) requirements are the most common procedural reason for non-covered service denials. Under the ACA and most state laws, the insurer must clearly communicate PA requirements. But the process still generates significant confusion.

When PA is required and you did not get it:

For elective, scheduled services: you are typically responsible for obtaining PA before the service. If your provider did not obtain it and you did not verify, you may still owe the full cost, even if the service would otherwise be covered.
For emergency services: federal and most state laws prohibit insurers from denying coverage solely on the basis of failure to obtain prior authorization for emergency care. If an emergency department claim is denied for lack of PA, this is appealable.
For urgent care: often a middle ground; check your plan’s specific urgent care definitions

The retroactive denial problem: Sometimes a PA is granted but then retroactively denied after the service is provided, based on the insurer’s post-service review concluding that the service was not medically necessary. This is a particularly frustrating scenario because you followed the rules.

Retroactive denial appeals should include: the original PA approval documentation, the provider’s clinical notes confirming the service was delivered as authorized, and an argument that the insurer cannot retroactively determine medical necessity after already approving the service.

What to Do When You Cannot Afford to Wait

The standard appeal process — internal review (30-60 days) followed by IRO (45 days) — can take three to four months. For serious medical conditions, waiting that long may not be clinically acceptable.

Expedited Internal Appeal

The ACA requires that insurers provide expedited internal appeal resolution within 72 hours when the standard timeframe would seriously jeopardize your health. To request expedited review:

Your treating physician must document that the standard timeline is clinically unacceptable
Submit this documentation with your appeal request, marked “EXPEDITED REVIEW REQUEST” clearly on all correspondence

Expedited External (IRO) Review

Available when: the service is urgently needed, the standard external review timeline would cause serious harm, or the denial is for an urgent ongoing course of treatment. IRO must resolve within 72 hours of request.

Concurrent Care Protection

If you are receiving an ongoing course of treatment that has been approved, and the insurer wants to reduce or terminate that treatment, the ACA requires that the insurer give you advance notice and allow you to appeal before the treatment is terminated. This “concurrent care” protection prevents abrupt mid-treatment denials from taking effect immediately.

State Emergency Insurance Department Contact

Most states have an emergency insurance complaint line or procedure for situations requiring immediate response. Identify this contact at naic.org before you need it.

Document Checklist for a Strong Appeal

Before submitting any internal appeal or IRO request, gather the following:

Medical documentation:

Complete copy of your Explanation of Benefits (EOB) with all denial reason codes
Original claim form and itemized bill from the provider
Physician’s letter of medical necessity — specific to your condition, signed by the treating specialist, not a general statement
Relevant diagnostic records (imaging reports, lab results, specialist consultation notes) demonstrating the clinical indication for the service
Treatment notes showing prior conservative treatments attempted (especially important for medical necessity appeals)
Peer-reviewed articles or clinical guidelines supporting the treatment — pulled from PubMed, NCCN, or professional society websites

Plan documentation:

Your Summary of Benefits and Coverage (SBC)
Relevant plan language — the actual policy sections, not just the denial letter summary
The insurer’s published medical coverage policies (most large insurers post these on their website under “coverage policies” or “clinical guidelines”)
Any prior authorization records, including approval history for similar services in prior years

Administrative records:

All correspondence with the insurer, including phone call notes (date, time, representative name, summary of conversation)
The denial letter with the specific date and appeal deadline
Any previous appeal decisions and their stated reasons

How to Escalate When IRO Is Not the Right Tool

An IRO external review is the standard second-line remedy, but it is not the only escalation path, and it does not cover every situation.

When IRO Review Is Not Available

ERISA self-funded plans without federal external review: Some large employer self-funded plans have limited external review rights. Check your plan’s Summary Plan Description (SPD) for the specific external review process.
Coverage disputes vs medical necessity disputes: IRO jurisdiction is primarily over medical necessity and experimental/investigational denials. A dispute over whether a service is categorically excluded from your plan (a coverage dispute) may be outside IRO scope — it requires legal argument about plan contract language.
Medicare beneficiaries: Medicare has its own appeals process separate from commercial insurance, handled through the BFCC-QIOs (Beneficiary and Family Centered Care Quality Improvement Organizations) and the Medicare Appeals Council.

Alternative Escalation Paths

State Insurance Department Complaint: Beyond just providing information, insurance department complaints create a regulatory record. If the insurer has a pattern of improper denials, regulators can act. Find your state’s department at naic.org.

Employee Benefits Security Administration (EBSA): For ERISA employer-sponsored plans, EBSA within the U.S. Department of Labor enforces your appeal rights. If an employer’s plan is not following required appeal procedures, EBSA can investigate. Contact: dol.gov/agencies/ebsa.

State Attorney General Consumer Protection Division: Bad-faith insurance practices — patterns of denying valid claims without reasonable investigation — may constitute consumer protection violations. Some state AGs have insurance-specific enforcement units.

Legal Action: After exhausting administrative remedies (required before suing under ERISA), federal court is available for ERISA plan disputes. For non-ERISA plans (individual market, state-regulated), state breach of contract and bad-faith claims are available. An attorney consultation — many take insurance cases on contingency — can assess whether litigation makes economic sense.

Understanding the “Experimental or Investigational” Denial

This category of denial is one of the most aggressively challenged in external review and one where patients most frequently prevail — when properly documented.

What Insurers Mean by “Experimental”

Insurers typically define experimental as: not yet approved by the FDA for the specific indication, not supported by sufficiently strong peer-reviewed evidence, or not yet widely accepted in the relevant medical community.

The problem: insurer criteria for “experimental” often lag behind current medical practice by 2-5 years. Treatments that have become standard of care in academic medical centers may still be classified as experimental by insurers using older coverage policies.

How to Document an Experimental Denial Appeal

FDA approval documentation: If the drug or device is FDA-approved for your specific indication, obtain the FDA approval letter or product labeling. The FDA’s database is publicly accessible at fda.gov.
NCCN Category 1 designation: For cancer treatments, NCCN (National Comprehensive Cancer Network) guidelines are the gold standard. Category 1 designation (“based upon high-level evidence, there is uniform NCCN consensus”) is powerful IRO evidence.
Professional society endorsements: American Heart Association, American College of Cardiology, American Gastroenterological Association — for each specialty, the relevant professional body’s clinical practice guidelines carry significant weight with IRO physician reviewers.
Peer-reviewed literature search: PubMed (pubmed.ncbi.nlm.nih.gov) is free and publicly accessible. Search for your specific treatment and diagnosis — include the most recent studies (last 3 years carry more weight) and those with the highest patient numbers or randomized controlled trial design.
The insurer’s own criteria: Many insurers post their clinical coverage policies online. If their own policy has not been updated and the treatment now meets their stated criteria, document this discrepancy directly.

Timing and Deadlines: What You Cannot Miss

Missing a deadline in the insurance appeal process can permanently forfeit your right to recovery, even if you would have won on the merits.

Stage	Deadline	Notes
Internal appeal filing	Typically 180 days from denial (ACA minimum)	Verify your specific plan; many plans set shorter deadlines
Internal appeal decision — pre-service	30 days (ACA standard)	For services not yet received
Internal appeal decision — post-service	60 days (ACA standard)	For services already received
External IRO request	Typically 120 days after internal appeal denial	State law may vary; check with your state commissioner
IRO decision — standard	45 days from request
IRO decision — urgent/expedited	72 hours	For urgent medical situations; request this when medically appropriate

Clock management tip: Request the insurer’s acknowledgment of your internal appeal submission in writing. This confirms the receipt date and starts the required response clock. If the insurer fails to respond within the required period, you may be entitled to request external review immediately even without a formal internal denial.

The Surprise Billing Connection: What It Does and Does Not Cover

The No Surprises Act (effective January 2022) has caused significant confusion about what it protects against — and what it does not.

What the No Surprises Act covers:

Unexpected bills from out-of-network providers at in-network facilities (emergency care and some scheduled care)
The insurer must generally pay out-of-network providers at the in-network rate, protecting you from balance billing

What the No Surprises Act does not cover:

Services that are categorically excluded from your plan’s coverage — the Act does not expand what services a plan must cover
Non-covered services are still non-covered regardless of network status
Elective care where you receive a Good Faith Estimate and consent in writing to out-of-network costs

If your claim was denied because the service is not covered by your plan (not because of network issues), the No Surprises Act’s dispute process does not apply. You need the standard appeal process described above.

Questions to Ask Before a Major Non-Covered Procedure

These questions, asked in advance, create a record that can support your appeal if a denial occurs:

To your treating physician:

“Can you document in my chart why this specific procedure is medically necessary for my diagnosis?”
“Are there alternatives that would be considered covered, and why do you believe this approach is superior for my case?”
“Can you cite the clinical guidelines that support this recommendation?”
“Will you be available to write a letter of medical necessity if my insurer denies coverage?”

To your insurer (before treatment):

“Is this specific procedure covered under my plan for my diagnosis code [CPT code / ICD-10 code]?”
“Does this procedure require prior authorization?”
“What clinical criteria must be met for this procedure to be covered?”
“Can you send me a written confirmation of what you just told me?”

Documentation discipline: Every phone call to your insurer should be followed by a written summary sent via the insurer’s member portal or secure message system, confirming what was discussed. This creates a contemporaneous record.

Tracking Your Appeal: Maintaining a Claims Journal

Every patient who has experienced a major insurance denial should keep a claims journal — a chronological record of every interaction related to that claim. This documentation habit has prevented many appeals from failing due to missing evidence.

Your claims journal should include:

Date and content of every denial letter received (staple the originals)
Date, time, representative name, and summary of every phone call with the insurer
Dates when you submitted documents, and the method (portal upload, certified mail, fax)
Dates of every appointment and test relevant to the claim
Any written communications received or sent (emails, portal messages, letters)
The specific language from your policy, highlighted, that supports your position

When you appear before an IRO or file a regulatory complaint, this record allows you to establish that you followed all required procedures, met all deadlines, and that the insurer’s position is factually and procedurally unsupported. A claimant with documentation wins more often than one who relies on memory.

What are the main reasons health insurers deny claims for non-covered services?

Common reasons include: the service is listed as an exclusion in your plan, the insurer determines it is not medically necessary, it requires prior authorization that was not obtained, the provider was out-of-network, or the service is considered experimental or investigational.

What is an internal appeal and how do I file one?

An internal appeal is a formal request to your insurer to reconsider a denial. Under the ACA, health plans must allow at least one internal appeal and must resolve it within 30 days for pre-service appeals and 60 days for post-service appeals. File in writing, include the denial letter, your physician's supporting documentation, and a clear explanation of why the denial is incorrect.

What is an Independent Review Organization (IRO) and when can I use it?

An IRO is an external entity, independent of your insurer, that reviews denied claims for medical necessity. After exhausting internal appeals, you have the right to request an external review by an IRO. Under federal and state law, the IRO's decision is binding on the insurer — this is a significant consumer protection.

How do I request external review by an IRO?

After your internal appeal is denied (or if your plan is not completing it within required timeframes), you may request external review through your state's insurance commissioner office or directly through the federal external review process at healthcare.gov for ERISA plans.

What is the deadline to request external review?

You generally have four months (120 days) after receiving the denial of your internal appeal to request external review. This varies by state, so verify with your state insurance department.

What is an Explanation of Benefits (EOB) and why does it matter for appeals?

An EOB is the document your insurer sends after processing a claim, showing what was billed, what was paid, and what was denied and why. The reason code and denial reason on the EOB are the starting point for any appeal — you need to address the specific reason stated, not just argue generally.

Can I appeal if my plan says a treatment is experimental or investigational?

Yes, and this is one of the strongest grounds for an IRO appeal. The IRO applies clinical standards and current medical evidence — if peer-reviewed literature supports the treatment for your condition, the IRO may override the insurer's experimental classification.

What if my doctor says it is medically necessary but the insurer disagrees?

Your physician's letter of medical necessity is essential but not always sufficient alone. An effective appeal also includes clinical guidelines supporting the treatment, peer-reviewed studies on the treatment's effectiveness, and precedents from similar IRO or court decisions.

How successful are external appeals?

Success rates vary by state, plan type, and reason for denial. External reviews of denials based on medical necessity show meaningful overturn rates — in some states, consumers win external reviews in 30–40% of cases. Experimental/investigational denials have lower overturn rates.

Does the No Surprises Act protect against non-covered service denials?

The No Surprises Act (effective 2022) addresses surprise billing from out-of-network providers, not the issue of a service being categorically excluded from coverage. These are different issues. The No Surprises Act does not expand what services are covered.

Can I contact my state insurance commissioner for help?

Yes. State insurance commissioners oversee insurance company conduct, and a complaint can prompt the insurer to review the denial more carefully. Commissioners can also provide information about your state's external review rights. Look up your state's commissioner at naic.org.

What if the denial is for a service I already received and paid out of pocket?

You can still appeal a post-service denial. An IRO can determine medical necessity retroactively. If the IRO overturns the denial, the insurer must reimburse you for the covered amount.

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