CMS and Its Claims Processing Contractors Issued Conflicting Guidance on the Proper Use of the KX Modifier for Part B Immunosuppressive Drug Claims  

Medicare Part B paid for some immunosuppressive drugs billed with the KX modifier that were not eligible for Part B payment. Of the 75 claims in our random sample, pharmacies had documentation to support the KX modifier for 65 claims but did not have support for the remaining 10.