Insurance Claim Denied? Here's Exactly What to Do — ClaimBack

Getting a denial letter from your insurance company feels like hitting a wall. But here is the reality most people never hear: over 50% of insurance appeals succeed when the patient actually files one. Insurers count on the fact that fewer than 1% of denied claims are ever appealed. That means the denial process is, in many cases, a business strategy — not a final medical decision.

Why Insurance Claims Get Denied

Understanding why your claim was denied is the essential first step before you can build an effective appeal. Insurance companies deny claims for a limited number of reasons, and each one has a specific counter-strategy.

Not medically necessary. The insurer's reviewer determined the treatment does not meet their internal clinical criteria. This is the most common denial reason and also the most commonly overturned on appeal. Your doctor's clinical judgment often directly contradicts the insurer's automated desk review.

Prior Authorization Denied: How to Appeal" class="auto-link">Prior authorization not obtained. Many procedures, medications, and specialist visits require pre-approval. If your provider did not obtain prior authorization before delivering care, the claim may be denied even if the treatment itself would have been approved. Under 29 CFR § 2560.503-1 (ERISA claims procedure regulations), insurers must disclose all applicable authorization requirements in the denial letter.

Out-of-network provider. You received care from a provider outside your plan's network. Under the No Surprises Act (42 U.S.C. § 300gg-111), you may be protected from surprise bills for emergency services and certain non-emergency services at in-network facilities — an important defense against many out-of-network denials.

Service not covered. The specific treatment, procedure, or medication is excluded under your plan's terms. However, many exclusions have exceptions — especially when medical necessity can be demonstrated or when the treatment is considered an essential health benefit under the ACA, 42 U.S.C. § 18022.

Timely filing exceeded. Your provider submitted the claim after the insurer's filing deadline. This is typically a provider-side error, and state insurance regulations often require exceptions for documented good cause.

How to Appeal a Denied Insurance Claim

Step 1: Read Your Denial Letter and Request Your Claims File

Your denial letter contains the exact reason for denial, the policy provision cited, your appeal deadline (typically 180 days for commercial plans, 60 days for Medicare/Medicaid), and instructions for filing. Request your complete claims file under ERISA Section 503 or the ACA — you are legally entitled to the medical reviewer's notes and the clinical policy bulletin used to evaluate your claim.

Step 2: Gather Supporting Medical Evidence

Collect medical records documenting your diagnosis and treatment history, a letter from your treating physician explaining why the treatment is medically necessary for your specific situation, clinical guidelines from relevant medical associations, peer-reviewed studies supporting the treatment, and the insurer's own clinical policy bulletin so you can show how your case meets their criteria.

Step 3: Write a Targeted, Evidence-Based Appeal Letter

Your appeal letter must reference your policy number, claim number, and denial date; quote the exact denial reason and rebut it with specific evidence; cite the applicable laws (ACA Essential Health Benefits, ERISA, Mental Health Parity Act (MHPAEA) Explained" class="auto-link">MHPAEA, state mandates); include your physician's letter of medical necessity; and state clearly what outcome you are requesting.

Step 4: Submit and Track Your Appeal

Send your appeal via certified mail with return receipt and through the insurer's online portal. Keep copies of every document submitted. Note the insurer's response deadline — 30 days for pre-service claims, 60 days for post-service claims under ACA regulations. Follow up in writing if no timely response is received.

Step 5: Escalate to External Independent Review: Complete Guide" class="auto-link">External Review or Your State Insurance Department

If the internal appeal fails, request an external review — an independent third party evaluates your case free of charge. External reviews overturn insurer denials 40 to 60 percent of the time. Simultaneously, file a complaint with your state Department of Insurance to create a regulatory record of the insurer's conduct.

What to Include in Your Appeal

• Denial letter with the specific reason code and the policy provision cited
• Treating physician's letter of medical necessity directly addressing the insurer's denial criteria
• Medical records, diagnostic results, and treatment history
• Clinical practice guidelines from the relevant medical specialty society supporting the treatment
• Evidence that prior required treatments were tried and the specific outcomes documented

Fight Back With ClaimBack

The appeal process is free, and external review costs nothing under the ACA. The only investment is your time — and the potential return is the full value of your denied treatment. Over 50% of properly filed appeals succeed. ClaimBack analyzes your denial, identifies the specific regulations and clinical guidelines that apply, and generates a professional appeal letter tailored to your case. ClaimBack generates a professional appeal letter in 3 minutes. Start your free claim analysis → Free analysis · No credit card required · Takes 3 minutes

Related Reading

• How to Write an Insurance Appeal Letter
• What Is Medical Necessity?
• Internal vs External Insurance Appeal