A denial letter is designed to feel final. It isn't. It's the opening offer in a process the law requires your insurer to run, and the numbers favor people who push back. The most upvoted post in a 6,794-post sample of health-billing threads we studied says it plainly: challenge every bill and denial, because a large share get reduced or reversed once someone actually reviews them.
The catch is that the fight is designed to cost you time. Hours on hold, transfers, letters that cite plan language nobody explains. This guide compresses it to the steps that matter.
Is appealing a denied claim actually worth it?
Yes. KFF's analysis of ACA marketplace plans found insurers denied a large share of in-network claims, consumers appealed fewer than 1 in 500 of those denials, and among appeals that were filed, a meaningful share were overturned. In Medicare Advantage the pattern is starker: more than 8 in 10 appealed prior-authorization denials get fully or partially overturned, yet only about 1 in 10 denials are appealed at all.
Step 1: Get the exact denial reason in writing
Your denial letter and your explanation of benefits (EOB) carry a denial code and a short reason. "Not medically necessary," "out of network," "prior authorization required," "experimental," or a coding rejection. If the reason is vague, call member services and ask two questions: "What is the specific denial reason code?" and "What plan language is this based on?" They must tell you.
Write down the date, the representative's name, and the call reference number. Ask for one if they don't offer it. Every fact you collect now is ammunition later (our guide to insurer phone calls covers the scripts and the escalation ladder when calls loop).
Step 2: Rule out the administrative stuff first
A large share of denials are clerical, and they die with one phone call or a corrected claim. Before writing any appeal letter, check for:
- A wrong procedure (CPT) or diagnosis (ICD) code (the itemized-bill decoder shows how to read them). Ask the provider's billing office to verify what they submitted and resubmit with a corrected claim if it's off.
- Missing information: chart notes, referral forms, an ID number typo.
- The claim went to the wrong insurer or an old plan on file.
- "No prior authorization" when one actually exists (see below).
If the fix is a corrected claim, the provider resubmits and the denial often just disappears. No formal appeal required.
Step 3: File the internal appeal
If the denial stands on its merits, file a formal internal appeal. Under the ACA, you generally have 180 days from the denial notice, and the insurer must decide within 30 days for care you haven't received yet or 60 days for care you already got. A strong appeal packet contains:
- A short cover letter: what was denied, why the denial is wrong, what you're asking for. One page.
- The denial letter and the relevant EOB.
- A letter of medical necessity from your doctor. Ask for it directly; clinics write these routinely.
- Records that support it: test results, chart notes, prior treatments that failed.
- Any prior authorization or reference numbers, and your call log.
Send it by the insurer's portal or certified mail so you can prove the date. If the care is urgent, say so explicitly and request an expedited appeal; plans must decide those quickly, in as little as 72 hours.
Step 4: If they say no again, go external
You then have the right to an external review: an independent third party, with no stake in the outcome, re-decides the claim, and the insurer is bound by the result. Your final internal denial letter must tell you how to request it. Standard reviews are decided within 45 days, expedited ones within 72 hours.
"But it was approved." When they deny it anyway
The most enraging denial pattern we see in patient threads: an MRI or procedure gets prior authorization, happens, and is then denied. People discover the fine print the hard way: prior authorization is not a guarantee of payment. It usually means the service was approved as medically necessary, while payment still depends on eligibility, coding, and plan terms at claim time.
It's still very winnable, because you hold the receipt. Call and give the authorization number, the approval date, and the name of anyone who confirmed it. Ask them to reprocess the claim against the existing authorization. If they refuse, that authorization letter is the centerpiece of your appeal, and the phrase "I received this service in good-faith reliance on your written authorization" belongs in your cover letter. Persistent bad-faith denials belong with your state insurance department, which takes consumer complaints and insurers answer to it.
Keep the receipts. All of them
Appeals are won on paper trails: who said what, when, and under which reference number. Keep the denial letter, EOBs, authorization numbers, and a log of every call. If a representative promises something, ask them to note it on the account, then write down that you asked.
How Kite handles this
This is the part Kite does for you. Text a photo of the denial letter and Kite reads it, explains the actual reason in plain English, drafts the appeal letter with your doctor's details filled in, and keeps every letter, number, and promise saved in your text thread. When someone says "that was never approved," you scroll up. Text Kite to start.
Free help if you're stuck
- Patient Advocate Foundation: free case management for denials tied to serious illness.
- Your state insurance department: consumer complaint lines that insurers must answer.
- If your coverage is through a large employer, the plan may be self-funded and federally regulated; your HR benefits contact can push, and the Department of Labor handles complaints.
- On Medicare? The process differs; see our plain-English Medicare appeals guide.