Your insurer denied a claim, refused a treatment, or called something "not medically necessary." It arrives like a verdict. But a large share of appealed denials get overturned — and the striking part is how few people ever appeal. The system is built to deflect the people who'll give up. The whole move is to not give up: calmly, in writing, on time.
Why "no" often isn't final
Many denials are fixable mistakes, not judgments
A wrong billing code, a missing prior authorization, a typo, an "out-of-network" flag that's wrong — a huge share of denials are clerical, not a real decision about your care. Those get fixed once you point them out.
"Not medically necessary" is often boilerplate
It's a common default denial that a letter from your doctor — explaining why the care was necessary, with records — frequently overturns.
Almost no one appeals — so appealing puts you ahead
Only a small fraction of denials are ever challenged. The insurer is betting you won't. Simply starting the appeal beats the bet.
There's usually a referee above the insurer
If the insurer's own (internal) appeal fails, you often have a right to an external, independent review by someone who doesn't work for them (in the US, external review; rights vary by country and plan). That changes how seriously they treat you.
What that means for you
Read the denial for two things: the reason and the deadline
The denial letter or EOB must state why and how long you have to appeal. Both are your foundation — and appeal windows can be short, so act quickly.
Get your doctor on your side
A "letter of medical necessity" and the supporting records from your provider are the single most powerful thing in most appeals. Doctors' offices do this routinely — ask.
Calm, written, and persistent beats angry
Treat it as a process, not an argument. Every call logged, every letter dated, each step escalated — that's what works.
The ladder — how to appeal
- Get the denial and its exact reason in writing, plus the appeal deadline. Start a log: dates, names, reference and claim numbers, what was said.
- Call to understand the reason — and rule out a simple error. Many denials are a wrong code or missing document the provider can correct, no formal appeal needed. Ask the insurer and your provider's billing office to compare notes.
- File the internal appeal — in writing, before the deadline. State what was denied, why it should be covered (cite your plan's own coverage language), and attach your doctor's letter of medical necessity and records. Keep copies.
- Request an external / independent review if the internal appeal fails. You often have the right to an outside reviewer whose decision the insurer must follow. The denial letter should explain how; if not, ask, or contact your insurance regulator.
- Bring in help. Your state/national insurance regulator or ombudsman, a patient-advocate or disease-specific nonprofit, or — if it's an employer plan — your HR/benefits team. Many will push on your behalf for free.
- Don't pay the disputed amount under pressure while you appeal, and keep escalating calmly. An open appeal changes what the provider and insurer can do.
Your appeal kit
Tick as you go.
The close
Insurers, like most institutions, win disputes by attrition — not by being right. The thing that beats that is an ordinary person who reads the denial, gets their doctor's backing, and climbs the appeal ladder one calm, written, on-time step at a time. You don't need to be an expert; you need a reason in writing, a deadline you respect, and the patience to use the ladder. More often than people expect, the "no" doesn't survive it. And if the bill itself looks wrong rather than the coverage, start with Is Your Medical Bill Wrong?