Claims Appeal

A claims appeal is the formal process to challenge a denial from your insurance company. Insurers can refuse to pay for a service for several reasons: the service is not a covered benefit, it was deemed not medically necessary, the provider was out-of-network, or prior authorization was not obtained. Federal law gives you the right to push back on every one of these denials.

Why most denials are appealable

Studies from CMS and state regulators consistently show that a meaningful share of properly documented appeals are overturned. Around half of well-documented external reviews end with the insurer’s decision reversed. Yet most members never file. The denial letter looks final, the language is intimidating, and the deadlines are short. None of that means the denial is correct.

The two-level structure

Federal law (the ACA, applied through 45 CFR Part 147) guarantees:

• Internal appeal: a full review by the insurance company itself, conducted by reviewers who were not involved in the original denial. Usually 30 days for a pre-service denial, 60 days for a post-service denial. Expedited review (within 72 hours) is available when delay would harm your health.
• External review: an independent review by a third party (your state’s Department of Insurance, the federal HHS contractor, or an independent review organization). Decisions are binding on the insurer. You typically get up to four months after the final internal denial to request external review.

Both levels are free. You do not need a lawyer.

What to include

Strong appeals share a structure:

• A copy of the denial letter and the Explanation of Benefits (EOB)
• A short cover letter that names the claim, the date of service, and the specific reason you believe the denial is wrong
• Medical records that document the diagnosis and the reasoning for the treatment
• A letter of medical necessity from your provider, especially if the denial cited “not medically necessary”
• Relevant clinical guidelines — many specialty societies publish them publicly, and citing them strengthens your case
• For network denials: documentation of every in-network provider you tried before going out-of-network

Common winning angles

• The denial cited the wrong policy provision or an outdated medical guideline
• The service was actually covered under a different benefit category
• The provider was in-network at the time of service even if the directory now shows otherwise
• The prior authorization was obtained but logged incorrectly
• The diagnosis code submitted does not match the clinical record (often a billing error your provider can correct)

Deadlines matter

Most internal appeals must be filed within 180 days of receiving the denial. Missing that deadline can forfeit your right to external review. Open the denial letter the same day it arrives and put the appeal deadline on your calendar.

Related terms

• Explanation of Benefits (EOB)
• Prior Authorization
• In-Network
• Out-of-Network

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