How to appeal a denied insurance claim
A practical guide to appealing a denied claim — internal vs. external review, what to include, and the deadlines you cannot miss.
Roughly 1 in 7 in-network claims gets denied, and a meaningful share of those denials are overturned on appeal. You have a legal right to a fair appeal process — but you have to act quickly and follow the procedure exactly.
Know your two levels of appeal
- Internal appeal — Reviewed by the insurer. Required first step. Must be filed within 180 days of the denial.
- External review — An independent third party reviews the case. Available after the internal appeal is exhausted, or immediately for urgent care. Insurer must accept the decision.
Step-by-step internal appeal
- Read the denial letter carefully
It will state the specific reason for denial and cite plan language or medical policy. This is the target you need to refute.
- Request the full claim file
Federal law gives you the right to free copies of all documents the insurer used to make its decision — medical records, plan documents, and reviewer notes. Request these in writing.
- Get a letter of medical necessity from your provider
The single most effective document in an appeal. It should describe your condition, the treatment, why it was medically necessary, and cite clinical guidelines or studies.
- Write a concise cover letter
State your member ID, claim number, denial date, and the specific decision you want reversed. Reference the plan language that supports coverage.
- Submit before the deadline
Send the appeal package by certified mail or via the insurer's portal. Keep copies of everything. Save the tracking number.
- Wait for the decision
Insurers must respond in 30 days for pre-service claims, 60 days for post-service. For urgent care, the answer is due within 72 hours.
If the internal appeal is denied
- Request an external review
You have 4 months from the final internal denial to request external review. Submit the form provided in your denial letter.
- Provide any new evidence
Additional records, second opinions, or new clinical studies that weren't in the first appeal.
- Wait for the binding decision
An independent reviewer (often a board-certified physician in the relevant specialty) decides. The insurer is required to comply with the decision.
FAQ
- Can I appeal a prior authorization denial before getting care?
Yes — and you should. Pre-service appeals have faster timelines (30 days, or 72 hours for urgent care) and let you avoid paying for care that gets denied later.
- Do I need a lawyer?
Usually not for the first two appeals. If you exhaust internal and external review and still believe coverage was wrongly denied, an attorney specializing in ERISA or health insurance law can advise on next steps.
- What if my employer is self-funded?
ERISA self-funded plans follow the same internal-appeal rules but their external review may go through a state or federal process depending on plan design. Check the denial letter for instructions specific to your plan.