Most denied insurance claims are not final. Insurers deny a meaningful share of claims on first submission, and a real portion of appealed claims get overturned or partially paid once someone actually pushes back. The process has two stages, internal appeal then external review, each with its own deadline and its own rules for what evidence counts. Knowing which stage you are in, and what the denial code actually means, matters more than how frustrating the letter feels. This guide walks through both stages and the tactics that most often change an outcome.
How the appeal process works
- Read the explanation of benefits or denial letter closely. It will cite a specific reason: not medically necessary, out-of-network, missing prior authorization, a coding error, or a plan exclusion. The reason determines your entire strategy.
- Call the insurer to confirm the exact denial code and what documentation would resolve it. This is not the appeal itself, just reconnaissance, and it is free.
- File a formal internal appeal in writing, referencing the claim number, the denial reason, and including supporting documents: medical records, a letter of medical necessity from your provider, and any relevant plan language.
- Request a peer-to-peer review if the denial involves medical necessity. Your treating doctor can speak directly with the insurer's reviewing physician, which resolves a surprising number of coverage denials that a letter alone cannot.
- If the internal appeal is denied, request an external review. For most plans, an independent third party unaffiliated with the insurer makes the final call, and that decision is typically binding on the insurer.
- Track every deadline in writing. Internal appeal windows are commonly around 180 days from the denial date; external review windows are often much shorter, sometimes 60 days or less after the internal appeal is denied.
Internal appeal vs external review
|
Internal appeal |
External review |
| Who decides |
The insurer, often a different reviewer than the original |
An independent third-party reviewer |
| Typical deadline to file |
Around 180 days from denial |
Often 60 days or less after internal denial |
| Typical response time |
Weeks; days for urgent cases |
Weeks; days for urgent or expedited cases |
| Cost to you |
Free |
Free in most jurisdictions |
| Is the decision binding? |
No, you can still escalate |
Usually binding on the insurer |
Urgent medical situations generally qualify for expedited review at both stages, which can compress these timelines to a matter of days. If your situation is time-sensitive, say so explicitly and ask about expedited or urgent-care appeal tracks.
What actually changes a decision
Generic appeal letters rarely move an insurer. What tends to work is matching the evidence to the specific denial reason: a letter of medical necessity for a "not medically necessary" denial, corrected billing codes for a coding-error denial, or documentation of an in-network referral for an out-of-network denial. For example, on a hypothetical $8,000 claim denied for lack of prior authorization, the fix is not a persuasive letter — it is going back to get the authorization documented and retroactively applied, which insurers often accept when the care itself was appropriate.
Persistence also matters more than most people expect. A claim denied once, appealed with the same information, and denied again is a dead end. A claim denied once, appealed with new documentation targeted at the actual denial code, has a real shot. If both appeal stages fail and the amount is significant, a written complaint to your state insurance regulator, or for employer plans the Department of Labor, can prompt a second look.
Common mistakes
Paying the bill before appealing. Payment can be read as accepting the charge, and it removes the financial pressure that motivates you to keep pushing. Appeal first; ask the provider to hold the balance or delay collections while the appeal is pending.
Missing the appeal deadline. These windows are shorter than people assume, and once they pass, most plans will not reopen the claim regardless of how strong your case is. Mark the deadline the day you get the denial letter.
Sending a generic complaint instead of targeted evidence. "This is unfair" does not move a reviewer. The specific denial code with matching documentation does.
Not asking your provider for help. Providers appeal denials constantly and often have templates, coding staff, and a billing advocate who can request a peer-to-peer review on your behalf at no extra cost.
FAQ
How long does an insurance appeal take?
Internal appeals often take a few weeks; external review can take a similar amount of time unless the case qualifies as urgent, in which case both stages can move in days.
Do I need a lawyer to appeal a denied claim?
No, most appeals are handled directly with the insurer and do not require legal representation. A lawyer becomes worth considering only for large, complex, or repeatedly denied claims.
What if I miss the internal appeal deadline?
Some plans allow a limited grace period for good cause, such as a medical emergency, but this is not guaranteed. Filing on time is always the safer path.
Can an external review really overturn an insurer?
Yes. External review decisions are typically binding on the insurer in a way internal appeals are not, which is why exhausting the internal process to unlock external review matters.
Where to go next
If an unpaid claim has already turned into a bill you cannot cover, our medical debt settlement guide covers negotiating what is left. If you need to bridge costs while an appeal is pending, see how to get a personal loan, and if a stalled bill has already hit your credit, how to raise your credit score fast covers the recovery playbook.