The 5 Most Common Medical Billing Denials — And How to Fix Them

1. Missing or Invalid Prior Authorization

Payers deny claims when prior auth was required but not obtained — or when the auth number is missing from Box 23. Fix: build a pre-auth matrix by payer and CPT range, and verify auth before the patient arrives.

2. Incorrect Patient Demographics

Name misspellings, wrong date of birth, or a transposed member ID account for roughly 25% of front-end denials. Fix: scan the insurance card at every visit and run eligibility verification 48 hours before the appointment.

3. Timely Filing Exceeded

Each payer has its own filing window — Medicare requires 12 months, some commercial plans only 90 days. Fix: submit claims within 5 business days of the date of service and document every submission with a clearinghouse confirmation number.

4. Bundling and Unbundling Errors

Submitting component codes that should be billed under a comprehensive code triggers NCCI edit denials. Fix: run all claims through an NCCI scrubber before submission.

5. Medical Necessity Not Supported

If the diagnosis code doesn’t justify the procedure in the payer’s LCD/NCD, the claim is denied. Fix: ensure the provider’s documentation supports the ICD-10 code chosen, and query the provider before claim submission when there’s a mismatch.