Check this list to see if any problem spots look familiar If Medicare sometimes denies your claims on the grounds that you sent a duplicate claim or because you billed for bundled services, you're not alone. Here's a list of Medicare's top-10 denials, compiled by averaging data from nine different Medicare carriers: • duplicate claim submissions • bundled services • individual provider number and/or group number missing from 24k or 33 of the CMS-1500 form • the payer does not deem the diagnosis linked to the procedure a "medical necessity" for that service • Medicare is the secondary payer but is being billed as primary • noncovered services • patient is not a Medicare beneficiary • UPIN and name of ordering or referring physician is missing or invalid • incorrect modifier usage • procedure is a "screening" service and therefore not eligible for payment.