Denial Pattern Library

The denial patterns AR teams see most — what each one means, why it happens, and how to prevent it before the claim goes out. Each article is original editorial content tied to the matching denial guide and real CARC codes.

Payer-specific notes appear only where the source registry has verified data — exact per-payer denial rankings vary by book of business and are not published.

Timely Filing Denials

The claim was submitted after the payer's filing deadline — the single most common reason clean claims go unpaid.

Full guide: Timely Filing →

Missing or Expired Authorization

CARC 197CARC 15

The service needed prior authorization and the payer has no record of an approval.

Full guide: Authorization →

Eligibility / Coverage Denials

CARC 27CARC 204

The payer could not confirm the patient was covered on the date of service.

Full guide: Eligibility & Coverage →

Medical Necessity Denials

CARC 50CARC 151

The payer determined the service was not medically necessary per its policy.

Full guide: Medical Necessity →

Missing Information / Unprocessable Claims

The payer returned the claim unprocessed because required data was missing.

Full guide: Missing Information →

Coding & Modifier Denials

The code, modifier, or diagnosis combination did not match what the payer expected.

Full guide: Coding & Modifiers →

Duplicate Claim Denials

The payer already processed the same claim and won't pay it twice.

Full guide: Duplicate Claims →

Non-Covered Service Denials

CARC 96CARC 204

The service is excluded from the patient's benefit plan — a coverage decision, not a data problem.

Full guide: Non-Covered Services →

Documentation Request Denials

The payer needs medical records before it will adjudicate the claim.

Full guide: Documentation Required →

Coordination of Benefits Denials

The claim should be paid by another insurance first, or the wrong plan was billed.

Full guide: Coordination of Benefits →