Does appealing cost anything?

No. Internal appeals and independent external review are free and are your legal right. A state insurance-commissioner complaint is also free.

Guides · Pillar guide · Updated July 2026

The complete guide to appealing a health insurance denial

Insurers denied roughly 1 in 5 in-network claims last year — about 85 million denials. Fewer than 1% were appealed, yet ~44% of internal appeals win and independent review overturns 40–50% of what reaches it. The gap isn't the odds. It's that almost no one understands the denial, and almost everyone misses the deadline. This guide closes both.

Step 1 — Decode the denial

Your denial arrives as a code on your Explanation of Benefits (EOB): CO-50, PR-197, and about a hundred others. The code is the whole story — it tells you what the insurer is actually claiming and how beatable it is. Look it up on our full list of denial codes or in the free decoder.

Step 2 — Set your clock (this is where appeals die)

Your deadline depends entirely on how you get your insurance, and the differences are brutal: 180 days for most employer and marketplace plans, 120 days for Original Medicare, about 90 days for Medicaid, and only 65 days for Medicare Advantage. Miss it and the denial stands — no matter how strong your case. Set the clock before anything else.

Step 3 — Is it urgent?

If this is care you still need right now, don't mail a letter — call and request an expedited appeal. When your health is at risk they must decide within 72 hours.

Step 4 — Build your case and write the letter

Match your evidence to the denial reason: a letter of medical necessity for a "not medically necessary" denial, a corrected code for a billing-error denial, proof of coverage dates for an eligibility denial. Send it certified and keep copies.

Step 5 — Climb the ladder

A "no" is never the last rung. After the internal appeal comes independent external review — a doctor who doesn't work for your insurer, whose decision binds them — then, depending on your plan, ALJ hearings and a state insurance-commissioner complaint. See the whole ladder here.

Don't fight it alone — and don't miss the deadline

AppealClock translates your denial, drafts your appeal letter, and watches every deadline so you can't miss it. Free, no account, your medical details never leave your device.

Start your appeal & set your clock →

Common questions

How long do I have to appeal a health insurance denial?: It depends on your coverage: 180 days for most employer and marketplace plans, 120 days for Original Medicare, about 90 days for Medicaid (varies by state), and only 65 days for Medicare Advantage.
Does appealing cost anything?: No. Internal appeals and independent external review are free and are your legal right. A state insurance-commissioner complaint is also free.