How to Appeal a Health Insurance Denial in 2026
Your insurance company denied your claim. Now what? The good news: most appeals succeed when patients actually fight back. This guide walks you through every option, from your first internal appeal to binding external review, with template letters you can use today.
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Why You Should Always Appeal a Denial
Insurance companies count on you giving up. According to KFF (Kaiser Family Foundation), fewer than 1% of people who receive a claim denial ever file an appeal. Yet when patients do appeal, the results are striking:
Appeal success rates by denial type
Sources: KFF Marketplace data (2024), HealthAffairs research, state insurance department reports
The math is simple: even the lowest-success category (“not covered”) gives you roughly a 1-in-3 chance of winning. For most denial types, your odds are closer to 2-in-3. And filing an appeal costs nothing except your time.
The denial rate is rising
Insurers denied about 19% of in-network claims in 2024, down slightly from 22.5% in 2023 but still historically high. UnitedHealthcare, the largest U.S. insurer, denied roughly 32% of claims. If you have insurance, there is a meaningful chance you will face a denial at some point.
Understanding Your Denial Letter
Every denial letter (sometimes called an Explanation of Benefits, or EOB) must include specific information by law. Here is what to look for and why each part matters for your appeal.
Key sections of a denial letter
The specific reason your claim was rejected (e.g., “not medically necessary,” “prior authorization required,” “not a covered benefit”). This determines your appeal strategy.
The specific section of your plan that the insurer says supports the denial. Request the full clinical policy bulletin if only a general reference is given.
You typically have 180 days from the date on the letter to file an internal appeal. Mark this date immediately.
How and where to submit your appeal (mailing address, fax number, or online portal). Your insurer must provide this information.
Information about requesting an independent external review after exhausting internal appeals. Under the ACA, this is your legal right.
First call to make after receiving a denial
Call the number on your denial letter and ask for three things:
- The specific clinical policy bulletin or medical criteria used to deny your claim
- The name and credentials of the reviewer who made the denial decision
- Confirmation of your appeal deadline and the mailing/fax address for appeals
Write down the date, time, name of the representative, and a reference number for every call.
The 5 Types of Denials and How to Fight Each One
Different denial reasons require different strategies. Identify your denial type below, then follow the targeted approach.
“Not Medically Necessary”
The most common denial type. Success rate on appeal: ~70%
The insurer claims you did not need the treatment, or that a cheaper alternative would have worked. They often base this on their own internal clinical policy bulletin rather than your doctor’s judgment.
How to fight it
- Request the insurer’s specific clinical criteria and show how you meet each requirement
- Get a detailed letter of medical necessity from your treating physician
- Include peer-reviewed medical literature supporting the treatment
- Document any alternative treatments that were tried and failed
- Request a peer-to-peer review between your doctor and the insurer’s medical director
“Prior Authorization Required”
Denied because approval was not obtained before the service. Success rate on appeal: ~65%
Your provider performed a service without getting advance approval from your insurer. This can happen when a provider forgets to submit the request, or when an emergency required immediate action.
How to fight it
- If your provider failed to get authorization, ask them to submit a retroactive authorization request
- For emergencies, argue that prior authorization was impossible due to the urgent nature of care
- Check if your state has a “gold carding” law that exempts certain providers from prior auth requirements
- If the provider error caused the denial, ask the provider to absorb the cost or help with the appeal
“Not a Covered Benefit” or “Excluded Service”
The service is excluded from your plan. Success rate on appeal: ~35%
The insurer says the service is specifically excluded from your plan. This is the hardest denial to overturn, but it is still worth appealing.
How to fight it
- Read your full plan document (not just the summary). Exclusions are sometimes more narrow than they appear.
- Argue the service falls under a different covered category (e.g., “reconstructive” rather than “cosmetic”)
- Check if ACA essential health benefits mandate coverage for your plan type
- For experimental/investigational treatments, provide clinical trial data and medical literature showing the treatment is accepted standard of care
“Out-of-Network Provider”
Denied because the provider was not in your plan’s network
You received care from a provider outside your insurance network. Note: the No Surprises Act (effective January 2022) protects you from surprise out-of-network bills for emergency services and certain non-emergency situations at in-network facilities.
How to fight it
- For emergencies, cite the No Surprises Act and the prudent layperson standard
- If no in-network provider was available, request a network adequacy exception
- If you were referred to an out-of-network provider by an in-network doctor, document the referral chain
- Check if the provider was incorrectly listed as out-of-network in the insurer’s directory
Coding or Billing Error
Wrong diagnosis code, incorrect procedure code, or data-entry mistake. Success rate on appeal: ~78%
The claim was denied because of an incorrect CPT code, wrong ICD-10 diagnosis code, or a simple typo. These are the easiest denials to fix.
How to fight it
- Call your provider’s billing department and ask them to review the codes submitted
- Compare the codes on your EOB with the codes on your itemized bill
- Ask the provider to submit a corrected claim (not a new claim) with the right codes
- If the insurer made the coding error, call them directly with the correct information
Internal Appeal: Step-by-Step
An internal appeal is your first formal challenge to the denial. Your insurance company must assign a reviewer who was not involved in the original decision. You have 180 days to file, and the insurer must respond within 30 days (pre-service) or 60 days (post-service).
Internal appeal timeline
Read the denial, note the reason, and mark your 180-day deadline on your calendar.
Request the clinical criteria, reviewer credentials, and confirm appeal submission instructions.
Get your doctor’s letter of medical necessity, relevant medical records, and any supporting research.
Use the template below. Send via certified mail with return receipt requested. Keep copies of everything.
The insurer has 30 days (pre-service) or 60 days (post-service) to respond. If they miss the deadline, your claim is “deemed denied” and you can proceed to external review.
Internal Appeal Letter Template
Tip: Always send appeals via certified mail with return receipt requested, or fax with a confirmation page. Keep copies of everything you send.
What makes a strong appeal?
- Doctor’s letter of medical necessity
- Specific plan language that supports coverage
- Peer-reviewed medical literature
- History of failed alternative treatments
- Emotional arguments without clinical backing
- Vague statements about your condition
- Threats of legal action (save that for later)
- Missing the filing deadline
Peer-to-Peer Review: How Your Doctor Can Overturn It
A peer-to-peer review is a phone call between your treating doctor and the insurance company’s medical director. It is one of the most effective and fastest ways to overturn a denial, particularly for “not medically necessary” decisions.
How peer-to-peer review works
Your doctor (or their staff) contacts the insurer to schedule a peer-to-peer review. The insurer must respond to schedule the call within 48 hours.
Your doctor explains the clinical reasoning, your specific situation, why alternative treatments are not appropriate, and how the treatment meets the plan’s medical criteria.
The insurance medical director may approve the claim on the spot, or issue a decision within a few days. This can bypass the entire formal appeal process.
Tips for a successful peer-to-peer
- Ask your doctor to prepare by reviewing the insurer’s specific clinical criteria before the call
- Have your doctor focus on objective clinical evidence, not emotional arguments
- Document which alternative treatments were tried and why they failed
- Reference published clinical guidelines and peer-reviewed studies
- Request the call early, as some insurers have tight windows (24-72 hours) for scheduling
Important: A peer-to-peer does not replace your formal appeal
File your written internal appeal at the same time you request a peer-to-peer review. If the peer-to-peer succeeds, you can withdraw the written appeal. But if you wait for the peer-to-peer and it fails, you may have lost valuable time on your appeal deadline.
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External Review: The Nuclear Option That Works
If your internal appeal is denied, you have the right to an external review by an Independent Review Organization (IRO). This is your most powerful tool. The IRO is completely independent from your insurance company, and its decision is legally binding on your insurer.
External review: key facts
How to request an external review
Check your denial letter. It must include instructions for requesting external review. If it does not, contact your insurer or state insurance department.
Submit a written request within 4 months of your internal appeal denial. Include your denial letters, appeal letters, and all supporting documentation.
Add new evidence. You can submit additional documentation that was not part of your internal appeal, including new medical records, updated research, or a second opinion.
Wait for the decision (up to 45 days). The IRO will review all medical evidence and issue a final determination. If they rule in your favor, your insurer must cover the service.
External Review Request Letter Template
Check with your state insurance department for any state-specific forms that may be required for external review requests.
Expedited Appeals for Urgent Situations
If waiting for a standard appeal timeline would seriously endanger your health, you can request an expedited (urgent) appeal. Your insurer must respond within 72 hours.
When you qualify for an expedited appeal
- Life-threatening conditions
The standard appeal timeline could seriously jeopardize your life or ability to regain maximum function.
- Severe pain management
You are experiencing severe pain that cannot be adequately managed without the denied treatment.
- Ongoing treatment interruption
You are currently receiving treatment (hospital stay, infusion series, medication regimen) that will be interrupted by the denial.
Key expedited appeal rules
- You can file an expedited internal appeal and an expedited external review at the same time
- You can request an expedited appeal by phone (you do not have to wait for a written submission)
- Your doctor can request the expedited appeal on your behalf
- The insurer must respond within 72 hours for both internal and external expedited reviews
- If the insurer does not respond within 72 hours, the claim is deemed approved in many states
State Insurance Department: When to Escalate
Filing a complaint with your state’s department of insurance adds regulatory pressure that an insurer cannot ignore. State regulators can investigate improper denials, fine insurers, and in some states, conduct their own independent review.
When to file a state complaint
- Your insurer is not following proper appeal procedures or timelines
- You believe the denial violates state insurance law
- Your insurer has not responded to your appeal within the required timeframe
- You want additional leverage while your appeal is pending
- The insurer is engaging in bad faith practices (repeated denials without clear reasoning)
States with the strongest consumer protections
Free Independent Medical Review (IMR) through the DMHC. The decision is binding on your insurer, and approval rates are among the highest in the country.
Strong external review process through the Department of Financial Services. Covers utilization review decisions and experimental treatment denials.
The Office of the Insurance Commissioner provides free appeal assistance and has a robust external review program.
Office of Patient Protection handles medical necessity disputes with an independent review process.
Every state has a department of insurance. Search “[your state] department of insurance complaint” to find your state’s filing process.
ERISA vs. Non-ERISA: Know Your Plan Type
If you get health insurance through your employer, your plan is likely governed by ERISA (the Employee Retirement Income Security Act). ERISA plans follow federal rules rather than state insurance laws, which creates important differences in how your appeal works.
ERISA Plans (Employer-Sponsored)
- Governed by federal law
- You must exhaust internal appeals before filing a federal lawsuit
- Maximum of two mandatory appeal levels
- 30 days for pre-service decisions, 60 days for post-service
- State insurance laws generally do not apply
- If the plan violates appeal procedures, you may skip to federal court (“deemed exhaustion”)
- Lawsuits filed under ERISA Section 502(a)
Non-ERISA Plans
- Individual/marketplace plans, government plans, church plans
- Governed by state insurance law and the ACA
- State insurance department has full jurisdiction
- External review through state process or HHS federal process
- Broader remedies available (state bad faith laws, punitive damages)
- State consumer protection laws may apply
- Lawsuits filed in state court
How to determine your plan type
- Check your Summary Plan Description (SPD), which your employer or HR department can provide
- If your plan is “self-funded” or “self-insured” by your employer, it is almost certainly an ERISA plan
- Government employee plans, church plans, and individual marketplace plans are generally NOT ERISA plans
- When in doubt, call your plan administrator and ask directly
Real-World Denial Examples and How to Win Them
ER visit denied as “not an emergency”
You went to the ER with chest pain. It turned out to be acid reflux, and your insurer denied the claim because the final diagnosis was not an emergency.
Winning strategy
Cite the prudent layperson standard, which is federal law under the ACA. The standard says coverage must be based on your presenting symptoms (chest pain), not the final diagnosis (acid reflux). A reasonable person experiencing chest pain would seek emergency care. Request your ER triage notes, which document your symptoms at arrival, and include them in your appeal. This argument has a very high success rate.
Surgery denied as “not medically necessary”
Your orthopedic surgeon recommended knee replacement surgery, but your insurer says conservative treatment (physical therapy) should be tried first.
Winning strategy
Document every conservative treatment you have already tried and why it failed. Have your surgeon write a letter of medical necessity detailing your imaging results, functional limitations, and pain levels. Include records of physical therapy sessions, injections, and any other treatments attempted. Request a peer-to-peer review so your surgeon can discuss the case directly with the insurer’s medical reviewer.
Medication denied, “try step therapy first”
Your doctor prescribed a specific medication, but the insurer requires you to try (and fail on) cheaper alternatives first.
Winning strategy
If you have medical reasons why the step therapy drugs are inappropriate (allergies, prior adverse reactions, drug interactions, or a condition that makes the alternative ineffective), document these in your appeal. Many states now have step therapy exception laws. Your doctor can request an exception based on clinical judgment and include evidence of why the prescribed medication is the appropriate first-line treatment for your situation.
Frequently Asked Questions
What is the success rate for health insurance appeals?
Internal appeals succeed roughly 44-56% of the time overall. Success rates vary by denial type: administrative errors are overturned about 78% of the time, medical necessity denials about 70%, and prior authorization denials about 65%. External reviews by independent organizations overturn insurer denials in approximately 40-60% of cases. Despite these odds, KFF reports that fewer than 1% of denied claims are ever appealed.
How long do I have to appeal a health insurance denial?
You have 180 days (6 months) from the date you receive your denial notice to file an internal appeal. After an internal appeal denial, you have 4 months to request an external review. For urgent or expedited appeals, the insurer must respond within 72 hours. Do not wait until the last minute. Start your appeal as soon as possible to allow time for gathering documentation.
Can I appeal if I already paid the bill?
Yes. Paying a medical bill does not waive your appeal rights. You can still file an internal appeal and request external review even after you have paid. If the appeal is successful, your insurer must reimburse the amount they should have covered. Keep all receipts and proof of payment.
Does my insurance company have to tell me why they denied my claim?
Yes. Under the ACA, your insurer must provide a written explanation that includes the specific reason for the denial, the plan provision relied upon, a description of any additional information needed, and instructions for how to appeal. If your denial letter does not include this information, that itself may be grounds for a complaint to your state insurance department.
Should I hire a lawyer for my insurance appeal?
For most appeals, you do not need a lawyer. The internal appeal and external review processes are designed for consumers to use on their own. However, consider consulting an attorney if: your claim involves a large dollar amount, you have an ERISA plan and your internal appeals have been exhausted, or your insurer is acting in bad faith. Many patient advocacy organizations offer free help with appeals.
What happens to my bill while my appeal is pending?
Call the provider’s billing department and let them know you have filed an appeal. Most providers will place a billing hold on the disputed amount while the appeal is being processed. Ask for the hold in writing, and request that the account not be sent to collections during the appeal period. If you are on a payment plan, continue paying undisputed amounts to protect your account status.
What if my ER visit is denied as “not an emergency”?
Appeal using the “prudent layperson standard,” which is federal law under the ACA. This standard requires insurers to cover emergency services based on your symptoms at the time you sought care, not the final diagnosis. If you went to the ER with chest pain that turned out to be acid reflux, coverage must still apply because a reasonable person would seek emergency care for chest pain. Request your ER triage notes and include them in your appeal.
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