What Is a Claim Denial?
A claim denial is a payer's decision, made after it has processed a claim, to refuse to pay some or all of it. The claim reached the payer, was adjudicated, and came back with a reason. That is what separates a denial from a rejection — and the difference decides who fixes it, how, and how long they have.
Updated 8 min read
Reviewed by Anwaar Tayyab
Director of Billing Operations ·
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Key takeaways
- A denial is a decision. The payer adjudicated the claim and refused it, in whole or in part, and returned standardized codes explaining why.
- A rejection is not a denial. A rejected claim failed an edit before adjudication, so there is no determination to appeal — it is corrected and resubmitted rather than argued.
- A denial is not the end of the claim. It is corrected and resubmitted, appealed, or written off — and choosing wrongly between those three is itself a common way to lose the money.
- Almost every denial is caused upstream of the denial, in registration, authorization, coding, or enrollment. That is why denials are read as data about a process, not just as a queue of work.
What a denial actually is
When a claim arrives at a payer, it goes through adjudication — the payer's process for deciding what, if anything, it owes. The payer checks the patient's coverage on the date of service, applies the plan's benefits and its own policies, and compares the claim against the contract it holds with the provider. A denial is one of the outcomes of that process: the payer has decided, and the decision is no.
The decision comes back on the remittance advice, carrying standardized codes that state the reason. A CARC gives the adjustment reason and, through its group code, says who bears the amount; a RARC adds the detail that makes the reason specific enough to act on. Those codes are the payer's account of its own decision, and they are the starting point for every response to it.
Partial denials are denials
Denial or rejection?
These two words are used interchangeably in conversation and they should not be. They describe different events, at different stages, and they call for different work. A rejection is a claim stopped by an edit — at the clearinghouse or at the payer's front door — before anyone adjudicated anything. A denial is the payer's decision after adjudication.
| Dimension | Rejection | Denial |
|---|---|---|
| When it happens | Before adjudication — the claim fails a format or data edit and is returned. | After adjudication — the payer has processed the claim and decided. |
| What went wrong | A structural or data problem: a malformed field, an invalid identifier, a member ID that does not match. | A coverage, policy, or contract problem: no authorization, not medically necessary under the policy, filed late, wrong plan billed first. |
| Where you see it | Usually in a clearinghouse or payer acknowledgment report. Medicare also returns some incomplete or invalid claims through the remittance process itself — still a return, still with no appeal rights. | On the remittance advice, with CARC and RARC codes stating the reason. |
| Can it be appealed? | No. There is no decision to contest, because the payer never made one. | Yes — an appeal asks the payer to reverse its decision, where the decision was wrong. |
| How it is resolved | Correct the data and resubmit. The payer receives it as a first submission. | Correct and resubmit, appeal, or write off — depending on whether the claim or the decision was wrong. |
| Does it count in the denial rate? | No. Nothing was denied, so a rejection is not in the numerator — and rejections are tracked in a separate pre-billing measure rather than in the denial rate. | Yes — it is what the denial rate measures. |
The practical consequence is a clock. A rejection is fixed and resubmitted quickly, but only if somebody reads the report it arrived in — and unlike a denial, no money movement announces it. An unworked rejection can sit invisible until the timely filing window closes, at which point a claim that was never wrong on its merits cannot be paid at all.
One instance of that is worth naming because it is so easily mistaken for a denial and so routinely worked as one. Where a claim carries an unlisted procedure code without the required narrative, CMS's instruction is to return it as unprocessable — a return rather than a determination, with no appeal rights, needing correction and resubmission while the filing clock keeps running. It presents in a worklist exactly like the denials around it.
Hard and soft denials
Within denials, a second distinction decides whether the money is still reachable. It is a working distinction rather than a code on the remittance: the payer does not label a denial hard or soft, the biller does, based on what the reason permits.
- Soft denial
- The payment is still possible without an appeal. Something is missing or wrong and can be supplied or corrected — records the payer asked for, an item the claim reported incorrectly. The claim is fixed and resubmitted, and no formal challenge is needed.
- Hard denial
- The payer has made a decision that will not change by resubmitting. Recovering the money means appealing it — or accepting it and writing the balance off. A medical-necessity decision and a timely-filing denial are both hard, but only one of them is usually worth appealing.
Choosing the wrong response wastes the deadline
Where denials come from
A denial is almost never made where it is found. By the time it appears on a remittance, the cause is weeks old and sits somewhere earlier in the revenue cycle — usually in a step nobody thought of as billing at the time.
At registration
The patient's coverage is captured wrongly, or their other coverage is not captured at all. The claim is then billed to the wrong plan, or to a plan that was not active on the date of service. See eligibility verification and coordination of benefits.Before the service
A service that required prior authorization was delivered without one, or with one that did not cover what was actually done.At coding and documentation
The service is reported in a way the payer's policy does not support, or the record does not establish the link to the patient's condition that medical necessity requires.In enrollment
The provider is not credentialed with the payer, or the enrollment lapsed, so the claim is denied on who rendered the service rather than on what was done. See credentialing.In the calendar
The claim was correct and simply arrived after the payer's filing window closed. Nothing about the care is ever reached.
This is why denials are treated as data rather than as a queue. A denial worked and paid is one claim recovered; the same denial traced to the registration step that produced it prevents the next hundred. Why Claims Get Denied works through the reason categories in detail.
What happens to a denial
Every denial ends in one of three places, and the reason code is what decides which. The claim is corrected and resubmitted, because the claim was wrong. The decision is appealed, because the claim was right. Or the balance is written off, because neither of the first two is warranted and pursuing it would cost more than it recovers.
Writing off is a legitimate outcome and not automatically a failure — but it should be a decision, not a default that happens when a deadline passes unnoticed. The denial appeal process sets out the ordered steps for the second path, and Appealing a Denial explains how to build the argument the process carries. The second path also does not stop at one attempt: an upheld appeal usually has a level above it, which is the levels of appeal.
The measure to watch is the mix, not the headline
Common questions
Is a denied claim the same as a rejected claim?
No, and the difference is the most consequential one in denial work. A rejected claim failed an edit before the payer adjudicated it, so there is no decision to appeal; it is corrected and resubmitted. A denied claim was adjudicated and refused, and it can be appealed. They usually surface in different places too — a denial arrives on the remittance advice, while a rejection comes back in an acknowledgment report that no payment movement announces. Not always, though: Medicare returns some incomplete or invalid claims through the remittance process itself, and those are still returns rather than decisions, carrying no appeal rights.
Can every denial be appealed?
Every denial can be appealed in principle, but not every denial should be. An appeal argues that the payer's decision was wrong; where the claim itself carried an error, correcting and resubmitting it is faster and more likely to be paid. Appeals are also governed by deadlines set by each payer, and a late appeal is generally decided on the date rather than the merits.
What is the difference between a hard and a soft denial?
A soft denial can still be paid without a formal challenge — something was missing or wrong, and supplying or correcting it resolves the claim. A hard denial will not change by resubmitting: recovering it requires an appeal, or a decision to write the balance off. The labels are a working distinction made by the biller from the reason given; the payer does not mark a denial as hard or soft.
Why do denials matter if the claim can just be resubmitted?
Because reworking a claim costs staff time that the original, correct claim would not have needed, and because not every denial is recoverable — a claim denied for late filing usually cannot be paid at all. Each denial also has a cause upstream in registration, authorization, coding, or enrollment, so a denial that is only worked rather than traced will keep being produced.
Key terms in this article
Defined once, on their own pages.
Continue learning
Where to go next on denials.
Why Claims Get Denied
The reason categories behind denials, and what each one points back to.
Reading a Denial
How to read CARCs, RARCs, and group codes on the remittance advice.
Denial rate
The metric that measures how often claims are denied, and how to read it.
The Denial Appeal Process
The ordered steps for challenging a payer's decision.
Corrections
The article said a rejected claim never entered the payer's system and was seen in an acknowledgment report rather than on the remittance. The second half is not reliably true: CMS's instruction for an incomplete or invalid Medicare claim (Pub. 100-04, Ch. 1, §80.3.1) lists return through the remittance process as one of the return routes, with a record of the claim retained, while still not denying it and not affording appeal rights. What separates a rejection from a denial is that no determination was made — not where the notice arrives. The key takeaway, the comparison table, and the first FAQ answer now say that. The same table also said a rejection sits outside both the numerator and the denominator of the denial rate. Only the numerator half holds: HFMA's remittance denial rate counts remittances carrying a denial indicator, and a returned claim is not denied — but its denominator is claims remitted, which a claim returned through the remittance process may well be. That row now rests on the absence of a denial, and on rejections being tracked in a separate pre-billing measure.
Authoritative sources
- 42 CFR § 405.924 — Actions that are initial determinations (opens in a new tab)
The Medicare contractor makes initial determinations on claims for benefits under Part A and Part B, and this section enumerates what counts as one. It states that a finding that a request for payment or other submission does not meet the requirements for a Medicare claim is not considered an initial determination — the regulatory basis for a rejected or returned claim having no decision in it to contest, since only an initial determination is appealable (42 CFR § 405.926, § 405.940).
- CMS Medicare Claims Processing Manual, Pub. 100-04, Chapter 1, §80.3 — Incomplete or invalid claims (opens in a new tab)
Defines an unprocessable claim and lists the routes by which one is returned to the provider, including detection inside the claims processing system and return through the remittance process. States that a claim returned as unprocessable for incomplete or invalid information does not meet the criteria to be considered a claim, is not denied, and is not afforded appeal rights, and instructs contractors not to deny such claims and afford appeal rights — the provider corrects and resubmits instead.
- X12 — Claim adjustment reason codes, and the claim adjustment group codes reported with them (opens in a new tab)
The X12 external code list for the codes that state why a claim or service line was paid differently than it was billed, published alongside the two-character group codes that accompany them and generally assign responsibility for the adjustment amount. One of the external code lists X12 maintains for the remittance advice, together with the remittance advice remark codes.
- HFMA MAP Keys — remittance denial rate (AR-5) and denial write-offs (AR-6) (opens in a new tab)
Healthcare Financial Management Association. Publishes the industry's standard revenue-cycle KPI definitions with their inclusions and exclusions. The remittance denial rate divides claims denied by claims remitted, counts claims adjudicated at the claim level, and counts zero-payment and partial-payment remittances alike where a denial is present — while claims the payer rejected during submission, rather than denied, are tracked in a pre-billing key instead.