Claim Denials · 2026 Guide
How to appeal a denied health insurance claim
A denial is not a final answer. It is the start of a process that most people never use, and that often works.
You can appeal almost any denied health insurance claim. You usually have 180 days from the date on the denial notice to file an internal appeal, and shorter for Medicare Advantage or urgent care. When patients and providers do appeal, they win roughly 40 to 80 percent of the time. Yet fewer than 1 percent of denied claims are ever appealed, which means most recoverable money is simply left behind.
Why so few people appeal, and why that is a mistake
Insurers operate on a simple assumption: most denials will never be challenged. The data supports them. Fewer than one percent of denied marketplace claims were appealed in 2023, according to KFF's analysis of federal data. The reasons are familiar. Denial letters are dense, deadlines are easy to miss, and most people do not know that an appeal is even an option.
That gap is the opportunity. More than half of all denials stem from administrative or procedural issues, not from a real medical judgment, which means a large share are correctable. Reworking a single denied claim costs a practice an estimated $25 to $181 in staff time, which is exactly why so many go unchallenged. The appeal works. The barrier is that almost no one files one.
How to appeal a denial, step by step
The internal appeal is the first stage, and it is a real sequence with a fixed order. Follow it in this order.
- Read the denial notice and find two things. The denial reason or code, and the appeal deadline. Both are printed on the notice. The deadline is the one number you cannot miss.
- Request your claim file and plan policy. Ask the insurer for the records used to deny the claim, and pull the plan language that defines the benefit. The denial often contradicts the plan's own wording.
- Match the denial to the right argument. An administrative or coding error is framed as a correctable mistake. A medical-necessity denial is answered with clinical documentation and the treating provider's judgment. A prior-authorization denial is answered with proof of the authorization attempt and the urgency of care.
- Write the appeal letter. State the claim, the denial reason, and the specific basis for overturning it, citing the plan language and the clinical record. Keep it formal, factual, and tied to evidence.
- File before the deadline and keep proof. Submit through the channel the notice specifies, and keep a dated copy of everything. If the internal appeal is upheld, request an independent external review.
Deadlines vary, and missing one ends the case. ACA plans commonly allow 180 days for an internal appeal. Medicare Advantage windows are shorter, and urgent or pre-service denials can require action within 72 hours. The exact deadline is on your denial notice.
Your odds depend on the denial type
Not all denials are equal. Administrative and coding denials, which come from missing information or a billing error, are overturned most often. Medical-necessity denials are harder but very winnable when the clinical record is strong, because payer policies frequently apply stricter criteria than the broader medical evidence. Across all types, appeals succeed roughly 40 to 80 percent of the time when they are filed.
For medical practices and billing teams
If your practice is absorbing a denial rate of 10 percent or higher, the problem is not whether appeals work. It is throughput: building documented, payer-specific appeals fast enough to beat the deadline, on every recoverable claim, without burning out your staff.
TruByte AI drafts the appeal for you. You submit a denial, and it returns the denial reason decoded, the win odds, the filing deadline, and a finished appeal letter for your review and signature. Every letter is reviewed by a person before it goes to the payer. It was built by a Registered Nurse, because clinical judgment is what wins the medical-necessity fights.
Fight your next denial free
We will draft your first five appeals at no cost. You see what comes back before you pay anything.
Start with a free appealFrequently asked questions
Can a denied health insurance claim be appealed?
Yes. Every health insurer must offer an internal appeal, and most denials can also go to an independent external review if the internal appeal is upheld. The right to appeal is built into the law for non-grandfathered plans.
What are my odds of winning an appeal?
Roughly 40 to 80 percent, depending on the denial reason. Administrative and coding denials are reversed most often. Medical-necessity denials are winnable with strong clinical documentation.
How long do I have to appeal?
Commonly 180 days from the date on the denial notice for ACA plans, shorter for Medicare Advantage, and as little as 72 hours for urgent or pre-service denials. The exact deadline is on your denial letter.
What is the difference between an internal appeal and an external review?
An internal appeal asks the insurer to reconsider its own decision. If it upholds the denial, an external review sends the case to an independent third party whose decision the insurer must follow.