Medicare Part B Outpatient Drug Coverage and J-Codes

Medicare Part B covers drugs that are administered by a healthcare professional in a clinical setting — as opposed to Part D, which covers self-administered drugs. The primary billing mechanism for Part B drugs is the J-code, an HCPCS Level II code that identifies the specific drug and unit of measure. Browse all J-codes in the code browser. The physician fee schedule includes Part B drug payment amounts for each J-code.

Medicare pays for most Part B drugs at Average Sales Price (ASP) plus 6%. ASP is calculated from drug manufacturers' sales data and is updated quarterly by CMS. The payment rate for a J-code is therefore dynamic — it changes every quarter based on market pricing. Billers should not assume a J-code's payment rate is fixed; check the current rate before entering a contract or quoting a patient's cost share.

Part B drug claims require the NDC in addition to the J-code. The NDC identifies the specific product administered — manufacturer, drug, packaging. Use the NDC lookup tool to cross-reference the dispensed product's NDC with its J-code before claim submission. Mismatches between NDC and J-code are a common cause of drug claim rejections.

Certain drugs have a benefit category question — Part B may not cover a drug if it is considered self-administered by most patients under typical circumstances. Documenting why the drug was administered by a professional rather than self-administered helps support coverage. Review quarterly updates for any coverage policy changes affecting Part B drug coverage, as CMS occasionally changes a drug's benefit category.