Why insurers deny claims
The most common denial reasons are: prior authorization not obtained or not approved, the service was deemed not medically necessary, the provider or service was out-of-network, a claim was filed incorrectly or past the deadline, or the service is excluded from your plan.
The denial reason code on your Explanation of Benefits is the starting point for your appeal. Different reasons require different responses. A prior authorization denial requires different documentation than a medical necessity denial.
The internal appeal process
An internal appeal is a formal request for your insurer to review its own decision. Under the Affordable Care Act, all non-grandfathered health plans must allow at least one internal appeal. You must file within 180 days of receiving the denial notice, though your plan may allow more time.
Your appeal must be in writing and should include: the claim number, the date of service, the specific denial reason, the medical justification for the service, a letter of medical necessity from your treating physician, and any relevant clinical guidelines or research that support the treatment.
Urgent and expedited appeals
For ongoing or urgent care, you can request an expedited internal appeal. Insurers must respond within 72 hours for expedited reviews, versus 30 to 60 days for standard reviews. Expedited appeals apply when waiting for the standard timeline would seriously jeopardize your health.
You can also request expedited external review simultaneously with an expedited internal appeal in urgent situations.
External review
If your internal appeal is denied, you have the right to an independent external review. External reviewers are certified organizations that are not affiliated with your insurer. Their decision is binding on the insurer.
You have four months from the internal denial to request external review. The external reviewer must decide within 45 days (or 72 hours for expedited reviews). Under ACA rules, this right applies to most medical necessity denials and rescissions. Grandfathered plans and some self-funded employer plans may use state or alternative processes.
Writing an effective appeal letter
The appeal letter should be precise and clinical, not emotional. State the claim number, the date of service, the service that was denied, and the specific denial reason. Then methodically rebut each ground for denial using your physician's letter, clinical guidelines, and any applicable coverage provisions.
Reference specific policy language from your Summary of Benefits and Coverage. If your plan covers a service for condition A but the insurer denied it for condition B, show why your diagnosis qualifies under the covered condition. Get your doctor to write a detailed letter that addresses the insurer's specific medical necessity criteria.
Frequently asked questions
What percentage of insurance appeals succeed?
Data varies by insurer and denial type. KFF analysis found that marketplace plan enrollees won about 39% to 59% of internal appeals and a higher percentage of external reviews, depending on the insurer. The success rate is higher when appeals include physician documentation and cite specific clinical guidelines.
Can I appeal a denial after 180 days?
Generally no, for internal appeals. The 180-day deadline is set by ACA rules. Some plans allow more time. If you miss the deadline, ask your insurer if a late appeal will be accepted and document any extenuating circumstances. Your state insurance commissioner may have additional options.
Do I need a lawyer to appeal?
No. Most internal appeals and external reviews can be handled without a lawyer. For complex or high-value denials, a patient advocate or healthcare attorney can help. Many patient advocacy organizations provide free assistance.
What happens if I lose the external review?
After external review, your remaining option is to file a complaint with your state insurance commissioner or bring a civil lawsuit if you are in a fully-insured state plan. Self-funded employer plans are governed by federal ERISA law, which has different remedies.