What Are Your Odds of Winning an Insurance Appeal? The Data

Most patients who receive an insurance denial don't appeal. Studies consistently find that fewer than 1% of denied ACA marketplace claims ever result in a formal appeal. Yet the patients who do appeal win a significant portion of the time. If you're wondering whether it's worth trying, the data says: yes, it almost certainly is.

The Baseline: How Often Do Appeals Succeed?

The honest answer is that appeal success rates vary significantly by:

• The type of insurance (Medicare Advantage, ACA marketplace, employer plan)
• The type of denial (medical necessity, network, experimental treatment)
• The quality of the appeal (documentation, specificity, physician involvement)
• The level of appeal (internal vs. external)

That said, published data gives us real benchmarks:

ACA marketplace external appeals: States that publish external appeal data show overturn rates of 30–50% for independent medical reviews. This means that if your internal appeal fails and you escalate to External Independent Review: Complete Guide" class="auto-link">external review, you have roughly a 1-in-3 to 1-in-2 chance of winning.

Medicare Advantage internal appeals: CMS data shows that Medicare Advantage plans reverse approximately 75% of denials at the internal appeal stage when patients submit complete medical records and physician documentation. This is a remarkable number — it suggests that most Medicare Advantage denials would not stand up to scrutiny if patients actually pushed back.

Medicare Advantage ALJ hearings: When denials reach the Administrative Law Judge stage, patients win over 80% of cases in some claim categories. The ALJ process is slow (often 6–12 months), but the success rate rewards persistence.

ERISA employer plan appeals: Success rates are harder to aggregate because these plans aren't required to report appeal data publicly. Research suggests internal appeal success rates of 25–40% when appeals include physician support letters and clinical documentation, compared to under 10% for unsubstantiated appeals.

What the Data Reveals About Denials

The high appeal overturn rates reveal something important about the initial denial process: a large proportion of denials are wrong.

When independent medical reviewers — physicians with no financial relationship with the insurer — reverse 30–50% of external appeals, they are finding that the insurer's denial was not supported by the clinical evidence. These aren't borderline cases where a reasonable person might disagree. These are cases where the independent reviewer found that the insurer's decision was simply incorrect.

This pattern is consistent with investigative reporting that has documented algorithmic denial practices, bulk reviews without individualized patient assessment, and the application of internal criteria that are more restrictive than accepted medical standards.

Variables That Most Affect Your Odds

Physician involvement

The single most powerful predictor of appeal success is whether your treating physician actively participates in the appeal. Appeals supported by a physician letter, peer-to-peer review, or medical record narrative from the treating provider succeed at substantially higher rates than appeals filed without physician input.

If your doctor believes the denial is wrong, ask them to help. Most will.

Specificity of the appeal

Generic appeals that simply say "I disagree with the denial" have low success rates. Appeals that:

• Identify the specific criteria the insurer claimed weren't met
• Present evidence showing those criteria were actually met
• Reference clinical guidelines and published evidence

...succeed at dramatically higher rates.

Denial type

Some denial types are easier to overturn than others:

• Administrative denials (coding errors, missing authorizations, timely filing) are the easiest to overturn — often a simple correction resolves them.
• Medical necessity denials succeed on appeal when physician documentation is strong. Success rates climb significantly with each level of appeal and physician involvement.
• Experimental/investigational denials for FDA-approved treatments with clinical guideline support are successfully overturned in a large percentage of external appeals.
• Blanket coverage exclusions (treatment categories excluded from the plan entirely) are the hardest to overturn through the appeal process, though they may be challengeable through other means.

Level of appeal

Each level of appeal gives you a better shot:

• Internal appeal (level 1): Lowest success rate, but worth filing
• Internal appeal (level 2, if available): Higher success rate
• External/independent review: Highest success rate at the insurer-review stage
• ALJ hearing (Medicare): Exceptional success rates

The Expected Value Calculation

Even conservative estimates suggest that filing an appeal is almost always worth it:

If a $10,000 denial has a 35% chance of being overturned, the expected value of appealing is $3,500. The cost of filing an appeal is primarily time — a few hours to gather documentation and write a letter. That's an exceptional return on time invested.

For denials involving ongoing treatment needs (medications, therapy, chronic care), the expected value compounds — a successful appeal can mean years of authorized coverage.

Fight Back With ClaimBack

The data supports fighting back. ClaimBack helps you build the kind of well-documented, specific appeal that succeeds — with guidance tailored to your specific insurer and denial type. Start at https://claimback.app/appeal.

Related Reading

• Insurance Appeal Success Rates by Insurer
• Internal vs. External Insurance Appeals
• How to Write an Insurance Appeal Letter