Your Insurance Denied Your Claim. Here's What to Do Next.
Charlie Alfarah, MEd, CDP® | MEd, Curriculum & Instruction (Science Education) · BS Health Sciences · Senior Certified Pharmacy Technician · DEI practitioner · Background in health and life insurance plan structure
You opened the letter. It says denied. And for a second, it feels like that's the end of it.
It isn't. Only 11% of patients ever appeal an insurance denial — but 53% of those appeals are overturned. The system isn't designed to make that statistic easy to find. This post is the exact process for fighting back.
What Your Denial Letter Is Actually Telling You
Most people read the denial and stop. That's what the letter is designed to make you do. It's formal, it sounds final, and it buries the one piece of information that actually matters.
The one sentence that matters most
Every denial letter contains a stated reason — usually a reason code plus a plain-language explanation. That sentence is the target of your entire appeal. Everything you write responds directly to it. Before you do anything else, find that sentence and write it down.
What "medical necessity" means when they use it against you
The most common denial reason is that the treatment wasn't deemed "medically necessary." It sounds clinical. It isn't. Medical necessity is an administrative determination made by a reviewer — not your doctor, not a specialist, often not even a physician in your condition's specialty. Your doctor said you need this. An insurance reviewer disagreed. That gap is exactly what an appeal is built to close.
Why Most People Never Appeal (And Why That's a Mistake)
Insurance companies denied claims at rates between 20% and 32% in 2024. UnitedHealthcare: 32%. Anthem: 23%. Aetna: 20%.
They count on most patients stopping at the denial. The letter is long, the language is confusing, and nothing in it tells you that appealing is free, that the deadline is months away, or that most people who appeal win. That's not an accident.
You have a legal right to appeal every denial. That right costs nothing to use.
What you need to know before you do anything else:
You have the right to appeal — and a hard deadline to do it (usually 30–180 days).
You need three documents before you write anything: the denial letter, your EOB, and your doctor's notes.
"Medical necessity" is the phrase insurers use to deny. Your appeal must use it back.
If your internal appeal fails, you can request an independent external review.
Appealing is free. Internal and external appeals cost nothing under federal law.
Most people who appeal win more than half the time. The system is beatable.
Your Appeal Window Is Shorter Than You Think
Federal law requires most insurers to give patients at least 180 days to file an appeal — but some plans start that clock the day the letter is sent, not the day you receive it. Don't assume you have time. Check the deadline on your denial letter and put it in your calendar today.
Internal appeal: the first step
An internal appeal goes directly back to your insurance company. This is the mandatory first step — you generally can't request an external review until you've completed the internal process. Most insurers have 30 to 60 days to respond to a standard internal appeal. For urgent or ongoing treatment, you can request an expedited review with a decision in 72 hours.
External review: if they say no again
If your internal appeal is denied, you can request an independent external review. An independent third party — not your insurer — reviews the denial. Their decision is binding. The insurer has to accept it. This is the level most people never know exists, and it's the most powerful tool in the process.
What You Need Before You Write a Single Word
Don't start writing until you have all three of these. An appeal filed without them has no target and no evidence. It will fail.
The denial letter
This is your roadmap. The specific denial reason tells you exactly what your appeal has to address. If it says "not medically necessary," your appeal is a medical necessity argument. If it says "experimental or investigational," your appeal cites peer-reviewed evidence for the treatment. The denial letter tells you what you're arguing against.
Your EOB
Your Explanation of Benefits confirms what was billed, what was denied, and what your plan says about coverage. Before you pay anything or accept any denial, read your EOB. What the EOB says you owe is what you owe — nothing more.
Your doctor's documentation
Clinical notes, referral letters, prior treatment history, lab results — anything your doctor has that supports the medical case for what was denied. If you're dealing with a step therapy denial, you specifically need documentation of every prior treatment you've already tried. No paper trail means you're starting from zero.
How to Write an Appeal Letter That Gets Read
An appeal letter has one job: answer the denial reason with evidence. Specific beats thorough. A focused two-page letter with the right documentation will outperform a six-page letter that buries the point.
Basic structure:
Your name, member ID, claim number, and date of service
One paragraph stating what was denied and why you're appealing
A list of supporting documents you're including
A direct closing request for reconsideration
The structure that works
Mirror the insurer's language back at them. If they denied on medical necessity grounds, your appeal argues medical necessity — using your doctor's clinical notes as the evidence. Reference the specific plan language that covers the treatment. Insurers review appeals against plan documents. When you cite the same language they do, the appeal looks like it knows what it's talking about. Because it does.
The phrase insurers respond to
"This denial contradicts the clinical evidence submitted by my treating physician."
That sentence signals three things: you have evidence, your physician is on record, and you're not going away. It belongs in almost every appeal.
How Leo strengthens your appeal letter
Writing an appeal is where most people get stuck — not because they don't have a case, but because they don't know how to frame it. Leo walks you through a set of questions before you write a single word.
How has the denied treatment — or its absence — affected your daily functioning? Has it caused or worsened anxiety, depression, disrupted sleep, or impaired your ability to work or care for yourself or your family? Has this denial blocked access to other parts of your care — follow-up appointments, related medications, specialist referrals?
Those answers aren't just context. They're evidence. Insurers are required to consider the impact of a denial on a patient's health and quality of life. Most appeal letters skip this entirely. Leo makes sure yours doesn't.
Find it under Leo > Fight a Denial in the app.
What Happens After You Submit
Get a confirmation in writing — a case number, an email, something on record. From that point:
Expedited/urgent appeals: decision within 72 hours
Standard internal appeals: decision within 30 days
External reviews: decision within 45 to 60 days
While you wait, document everything. Call logs, follow-up emails, any communication with your insurer — write it down with dates. If the deadline passes and you haven't heard back, that silence is actionable. Contact your insurer in writing and request a status. If they've missed their own deadline, that's a compliance issue you can raise with your state insurance commissioner.
When the Appeal Fails: What's Left
Most appeals don't get here. But if yours does, three options remain.
State insurance commissioner
Every state has one. Filing a complaint costs nothing, takes under an hour, and creates a paper trail the insurer is required to respond to. It won't overturn the denial on its own, but it applies real pressure.
External independent review
If you completed the internal process and were denied again, and haven't yet requested an external review, this is your next move. It's free, required by law for most ACA-compliant plans, and the decision is binding.
The No Surprises Act (if balance billing is involved)
If your denial involves a bill from an out-of-network provider you didn't choose — an anesthesiologist, an ER physician, a specialist at an in-network facility — the No Surprises Act may mean you legally don't owe what they're billing you. This is a separate protection from the standard appeals process.
Frequently Asked Questions
How long do I have to appeal an insurance denial?
Usually 180 days from the denial date, but check your specific plan — some are shorter, and the clock may start from the date the letter was sent, not the date you received it.
What if I miss the appeal deadline?
You may be able to request a late appeal if you have a documented reason — illness, failure to receive notice, or another qualifying circumstance. If the insurer refuses, contact your state insurance commissioner.
Can my doctor appeal on my behalf?
Yes. A peer-to-peer review is when your treating physician calls the insurer's medical reviewer directly to argue the case. It doesn't replace your appeal — it supplements it. Ask your doctor if this is an option before you file.
What is an external review?
An independent third party — not affiliated with your insurer — reviews the denial. Their decision is binding on the insurance company. You can request this after your internal appeal has been exhausted.
Does appealing cost anything?
No. Internal and external appeals are free under federal law for most health plans.
What if my insurance is through my employer?
Self-funded employer plans operate under federal ERISA rules, not state insurance law. The appeals process is similar, but escalation complaints go to the U.S. Department of Labor — not your state insurance commissioner. External review rights still apply for most employer plans.
Your Next Step
Your insurance denied you. Your appeal window is open. And it costs nothing to use it.
Leo walks you through the questions that make an appeal letter stronger — quality of life, mental health, barriers to care — before you write a single word. Download ProjectLeo free and start your appeal today.
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Leo provides health information and guidance, but does not replace professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider about your health concerns.
