Claim Denial

A claim denial is a payer's formal refusal to reimburse a healthcare provider for a submitted claim. Denials are communicated via Explanation of Benefits (EOB) documents for paper remittances and Electronic Remittance Advice (ERA) transactions for electronic processing, both of which include standardized codes explaining the reason for the denial.

Denials are not permanent. Most can be reversed through a reconsideration, corrected claim, or formal appeal, provided the provider understands the reason for the denial, responds correctly, and does so within the payer's required timeframe. The critical variable is whether the billing team works the denial at all: industry data suggests roughly 50-65% of denied claims are never reworked, representing permanent revenue loss.

What is the difference between a denial and a rejection?

These terms are often used interchangeably but refer to distinct outcomes in the claim adjudication process.

A rejection occurs before adjudication. The claim fails basic technical validation at the clearinghouse or payer and is returned to the provider without being processed. Rejections typically indicate format errors, missing required fields, or invalid code combinations. A rejected claim must be corrected and resubmitted; it has not been "denied" and does not carry a CARC code.

A denial occurs after adjudication. The payer received and processed the claim but determined not to pay it (or to pay less than billed). Denials carry CARC and often RARC codes and are subject to the payer's appeals process. The provider must follow specific reconsideration or appeal procedures to contest a denial.

What are the most common denial categories?

Denials cluster into recognizable categories, each requiring a different resolution approach:

Eligibility denials: The patient was not covered under the submitted plan on the date of service. Resolution typically requires verifying the correct payer and member ID, potentially resubmitting to a different plan or as self-pay.

Authorization denials: The service required prior authorization that was not obtained. Resolution depends on whether authorization can be obtained retroactively. Some payers allow this, others do not.

Medical necessity denials: The payer determined the service was not medically necessary based on the documentation submitted. Resolution requires a formal appeal with supporting clinical documentation, often including the treating physician's notes and relevant clinical guidelines.

Coding and bundling denials: The procedure codes, modifiers, or diagnosis codes are incorrect, or the payer has a bundling rule that prevents separate reimbursement for certain code combinations. Resolution requires a corrected claim.

Timely filing denials: The claim was submitted after the payer's filing deadline. Resolution requires demonstrating, with documentation such as clearinghouse confirmation, that the original submission was timely.

Coordination of benefits (COB) denials: The payer received a claim but believes another plan should be primary. Resolution involves coordinating between the two payers to establish correct primary/secondary billing order.

Duplicate claim denials: The payer believes the claim duplicates a previously processed claim. Resolution requires verifying whether a true duplicate was submitted or whether the payer incorrectly matched the claim to a prior one.

What does the denial resolution process look like?

Resolution paths vary by denial type, but the general process follows a consistent pattern: identify the denial reason from the CARC/RARC codes, categorize the denial, determine the correct action, gather any required documentation, and submit the appropriate response within the payer's deadline.

Most commercial payers allow one level of reconsideration (an informal review) before requiring a formal appeal. Medicare has a defined five-level appeals process: redetermination, reconsideration, Administrative Law Judge hearing, Medicare Appeals Council review, and federal court review. Medicaid appeals processes vary by state.

Why does denial volume matter at the system level?

The average denial rate across U.S. healthcare providers is approximately 5-10% of submitted claims by volume. At scale, this creates enormous administrative burden. Estimates suggest that the healthcare industry spends over $19 billion per year on the administrative work of processing, appealing, and writing off denied claims, a cost that ultimately passes through to providers, payers, and patients.