BillSherpa · Emergency & Panic Guides · Updated 2026

My insurance denied my claim — step by step guide to fighting back

Getting an insurance denial feels like hitting a wall. But here's what the insurance company doesn't tell you: more than half of all denied claims that are appealed get reversed. The denial is not the end of the road.

First: understand why it was denied

Common denial reasons include: not medically necessary, out of network, prior authorization required, coding error, experimental treatment, or duplicate claim. The reason determines your appeal strategy.

Step by step: how to appeal

1. Read the denial letter carefully — note the specific reason code, claim number, date of service, and appeal deadline. The deadline is critical.
2. Get your medical records for the denied service from your provider. You have the right to receive them within 30 days under HIPAA.
3. Ask your doctor to write a letter of medical necessity explaining why the service was required for your specific condition.
4. Submit your internal appeal — appeal letter, doctor's letter, medical records, and supporting clinical guidelines. Send certified mail. Keep copies.
5. If internal appeal fails: request external review by an independent third party. Their decision is binding on the insurance company in most cases.
6. File a complaint with your state insurance commissioner if the insurer is unresponsive or improperly denies your appeal.

Deadlines you cannot miss

• Internal appeal: Usually 180 days from the denial letter date
• External review: Usually 60 days after the internal appeal final decision
• State complaint: Varies by state — typically 1–2 years from denial