Good news: The most common rejection reasons are also some of the easiest to prevent If you've compiled a list of your top-10 denials, compare it with Medicare's so you can determine where you stand compared to other practices' most frequent denial reasons. Each Medicare carrier lists its top-10 reasons for denying claims. The following denials represent the top-10 reasons, compiled by averaging data from nine different Medicare carriers: 1. Duplicate claim submission 2. Bundled services 3. Individual provider number and/or group number missing from 24k or 33 of the CMS-1500 claim form 4. The payer does not deem the diagnosis linked to the procedure a "medical necessity" for that service 5. Medicare is the secondary payer but is being billed as primary 6. Noncovered services 7. Patient is not a Medicare beneficiary 8. UPIN and name of ordering or referring physician is missing/invalid 9. Incorrect modifier use 10. Procedure is a "screening" service and therefore not eligible for payment.