Appealing a Denial: When, What, and How Long You Have
An appeal is not a resubmission with a stronger tone. It is a formal argument that the payer decided wrongly under its own rules, and it succeeds or fails on two things: whether it was the right response to that denial at all, and whether it answers the specific reason the payer gave with evidence attached.
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Key takeaways
- Appeal when the decision was wrong. Correct and resubmit when the claim was wrong. Choosing wrongly costs the deadline, and the deadline is usually what decides the claim.
- An appeal answers the reason the payer gave. Restating that the service was performed answers nothing the payer disputed.
- Deadlines are set by the payer — in policy or in the contract — and run from the decision, not the date of service. There is no single industry window.
- Medicare publishes a defined multi-level appeals process; commercial payers set their own levels. The rules that apply are always that plan's.
- Not appealing is a legitimate decision. Not appealing by accident, because a deadline passed unnoticed, is not.
First: should this be an appeal at all?
This question decides more outcomes than the quality of the writing does. An appeal argues that the claim was right and the decision was not. If the claim carried an error — a wrong code, a missing item, the wrong plan billed first — then the payer's decision was correct on what it received, and no argument will change it. That claim needs correcting and resubmitting, which is faster and far more likely to be paid.
Reading the codes is what answers this, which is why reading the denial comes before deciding the response. The reason code and its group code together usually tell you whether the payer is disputing your claim or applying its policy.
| If the denial says | The right response | Why |
|---|---|---|
| The claim reported something incorrectly | Correct and resubmit | The decision was right on what was received. An appeal argues a point the payer never got wrong. |
| Information is missing | Supply it — usually a corrected claim, not an appeal | Nothing is in dispute yet. This is a soft denial: the payer is asking, not refusing. |
| The service was not medically necessary | Appeal, with the clinical record | The evidence that answers it usually already exists and simply was not in front of the reviewer. See medical necessity. |
| No authorization was on file | Depends — check before choosing | If one existed, appeal with the reference. If none existed, an appeal argues the payer should waive its own rule, which is a much weaker case. |
| The claim was filed late | Appeal only with proof of timely receipt | The argument that works is documentary — an acknowledgement showing receipt inside the window. Some payers recognize limited exceptions, so the plan’s own policy is worth reading before writing the balance off; absent proof of receipt or a stated exception, there is little to argue. See timely filing. |
| Another plan is primary | Bill the other plan — not an appeal | The payer is right: it is not first. See coordination of benefits. |
The row that costs the most money is the fourth. Authorization denials look identical whether an authorization existed or not, and the two need opposite responses — so the check comes before the decision, not after a rejected appeal.
The clock, and where it is defined
Appeals are governed by deadlines, and a missed deadline generally ends the matter regardless of the merits. This is the part of appeals that is least forgiving and most often misunderstood, for a specific reason: there is no single industry deadline to learn. The window is set by each payer, in its published policy or in the provider contract, and it varies between them.
Two different clocks, running from different events
Medicare is the case where the structure is public and defined. CMS publishes a multi-level appeals process for Medicare claims — a first-level review by the contractor that made the decision, then successive levels of independent review, each with its own deadline and its own filing requirements. Commercial payers set their own structure: often an internal review, sometimes a second internal level, sometimes an external one, with the specifics in the contract.
No day counts are printed here on purpose. Medicare's timeframes are published by CMS and are subject to change, and every commercial payer's are its own. A number copied into an article is a number that can be wrong at the moment someone relies on it — and in a matter decided by dates, being approximately right is the same as being wrong. The applicable deadline is the one in that payer's current policy, every time.
What an appeal has to argue
An appeal that recites the encounter fails. The payer is not disputing that the patient was seen or that the service was performed — it is disputing something specific, stated in the reason code. An appeal that does not answer that specific point has not engaged with the decision at all, however thorough it is about everything else.
- Name the decision being contested
- Identify the claim, the line, and the reason returned. The reviewer needs to know which decision is being challenged before anything else in the letter means anything.
- Answer the reason that was given
- Address the payer's stated basis directly. If the reason is that necessity was not established, the appeal establishes it. If the reason is that no authorization was on file, the appeal produces the authorization. One point, answered.
- Attach the evidence, do not describe it
- The clinical record, the authorization reference, the acknowledgement showing timely receipt, the contract language. A reviewer decides on what is in front of them; a reference to a record that is not attached is not evidence.
- Cite the rule the payer is applying
- The strongest appeals argue within the payer's own framework — its coverage policy, its contract — rather than on general fairness. The argument is not that the decision was unreasonable; it is that the decision was wrong under the plan's own rules.
The evidence usually already exists
For the procedure itself — the ordered steps of building, submitting, and tracking an appeal — see The Denial Appeal Process, which is where those steps live.
Knowing whether the appeals are working
Appeals cost staff time on money that was already owed, so it is worth knowing whether they are landing. The measure is the appeal overturn rate — the share of appealed denials the payer reverses — and it is more interesting than it first looks, because it does not read in one direction.
A high overturn rate can mean the appeals are well-built. It can equally mean denials are being issued that should never have been issued — a decision reversed on appeal was a decision that was wrong the first time. It can also simply mean only the most certain cases are being appealed at all, while winnable ones are written off unexamined. A low rate can mean weak appeals, or that everything is being appealed regardless of merit.
So the rate is read beside how many denials were appealed, and which. You can calculate it from your own figures with the appeal overturn rate calculator, and read it against your denial rate — the two together say something neither says alone.
The best appeals program is a smaller one
Common questions
How long do I have to appeal a denial?
That depends on the payer, and we deliberately do not print a number. Appeal windows are set by each payer in its published policy or in the provider contract, and they vary; Medicare's levels and timeframes are published by CMS and are subject to change. The applicable deadline is always the one in that payer's current policy. Note also that the appeal clock runs from the payer's decision, not from the date of service — it is a different clock from timely filing.
Should I appeal or send a corrected claim?
Appeal when the claim was right and the decision was wrong; correct and resubmit when the claim itself carried an error. The reason code and its group code usually tell you which. This choice matters more than the quality of the appeal: an appeal arguing a point the payer never got wrong will not be granted, however well it is written, and the attempt is not free — the appeal window is running while it is considered.
What should an appeal actually contain?
It should identify the specific decision being contested, answer the exact reason the payer gave, attach the evidence rather than describe it, and argue within the payer's own rules — its coverage policy or the contract. An appeal that recites the encounter without addressing the stated reason has not engaged with the decision. A reviewer decides on what is in front of them, so a record referenced but not attached is not evidence.
Is a high appeal overturn rate good?
Not necessarily, which is what makes it an interesting metric rather than a simple one. A high rate can mean appeals are well-built — or that denials are being issued that should not have been, since a reversed decision was a wrong decision. It can also mean only the most certain cases are appealed while winnable ones are written off. Read it beside the volume appealed and the reasons behind them, and treat any external benchmark as directional rather than a target.
Can a rejected claim be appealed?
No. A rejection failed an edit before the payer adjudicated it, so there is no decision to contest — it is corrected and resubmitted, and it arrives at the payer as a first submission. Only a denial, which is a decision made after adjudication, can be appealed. This is why the denial-versus-rejection distinction is worth getting right early.
Key terms in this article
Defined once, on their own pages.
Continue learning
Where to go next on denials.
The Denial Appeal Process
The ordered steps of an appeal — the procedure this article decides when to use.
Appeal overturn rate calculator
Calculate the share of your appealed denials that were reversed.
Preventing Denials
The controls that make the appeal unnecessary in the first place.
CMS
The agency that publishes the Medicare appeals levels and their timeframes.
Authoritative sources
- Centers for Medicare & Medicaid Services — Medicare appeals (opens in a new tab)
Publishes the Medicare appeals levels, their filing requirements, and their current timeframes. The authoritative source for Medicare deadlines.
- X12 — Claim Adjustment Reason Codes (opens in a new tab)
Maintains the national code set stating the reason a claim was adjusted — the reason an appeal must answer.
- Healthcare Financial Management Association (HFMA) (opens in a new tab)
Publishes standard definitions for revenue-cycle metrics, including denial and appeal measures.