What is Appeal?
Also called: claim appeal · reconsideration · redetermination
An effective appeal answers the specific CARC and RARC rather than restating that the service was performed. If the denial cites medical necessity, the appeal cites the coverage policy and points to the documentation satisfying it. If it cites missing authorization, the appeal supplies the authorization number or argues the retroactive exception.
Because roughly 70% of appealed denials are overturned, an appeal backlog is not an administrative annoyance. It is a receivable being written off by default.
Where Vizora handles this
Primary sources
Where "Appeal" is defined by the bodies that set the rules, rather than by us.
- Medicare claims appeals process (opens in a new tab)
Centers for Medicare & Medicaid Services — The five levels of appeal, what each requires and the deadline for each. Missing a level's deadline ends the appeal regardless of the claim's merits.
- Claim Adjustment Reason Codes (CARC) (opens in a new tab)
X12 — The authoritative, maintained CARC list. Our denial code lookup explains these in plain English; X12 is where the canonical definitions live.
- Claims denials and appeals research (opens in a new tab)
KFF — Independent analysis of in-network denial rates and how rarely denials are appealed on the marketplace side. Useful counterweight to vendor-published statistics.
Last reviewed August 20, 2026
Related terms
Denial
A denial is a claim the payer adjudicated and refused to pay. It differs from a rejection, which never entered adjudication. That distinction determines your remedy: a rejected claim is corrected and resubmitted, while a denied claim must be appealed within the payer's deadline.
Timely Filing
Timely filing is the deadline by which a payer must receive a claim. Limits commonly range from 90 days to one year from the date of service, vary by payer and contract, and are shorter for secondary claims. A claim denied for timely filing is generally unappealable and unbillable to the patient.
Medical Necessity
Medical necessity is a payer's determination that a service was appropriate for the patient's condition under its coverage policy. It is established by the pairing of diagnosis and procedure codes and supported by the documentation — which means a medically necessary service can still be denied if the coding does not demonstrate it.
CARC
A claim adjustment reason code explains why a payer adjusted or denied a payment. Maintained by X12, each CARC carries a group code — CO for contractual obligation, PR for patient responsibility, OA for other adjustment — which determines whether the balance may be billed to the patient.
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