Average Sales Price information is published quarterly by the Centers for Medicare and Medicaid Services (CMS) in the ASP Medicare Part B Drug Pricing File or Not Otherwise Classified (NOC) Pricing File. Providers are encouraged to review the ASP Pricing files poste d quarterly by CMS and listed by HCPCS on CMS.gov for updates. Payment allowance limits that are not included in the ASP Medicare Part B Drug Pricing file or Not Otherwise Classified (NOC) Pricing File, are based on the published Wholesale Acquisition Cost WAC) or invoice pricing. In determining the payment limit based on WAC, the contractors follow the methodology specified in Publication. 100-04, Chapter 17, Drugs and Biologicals, for calculating the Average Wholesale Price (AWP), but substitute WAC for AWP . Providers are encouraged to check with their local MACs for information on established rates. Providers are also encouraged to check with payers to determine if an invoice is required to be submitted with the claim and/or in Box 19 of the CMS-1500 claim form.