CMS established two Healthcare Common Procedure Coding System (HCPCS) Level II modifiers to identify 340B-acquired drugs:
Modifier “JG” Drug or biological acquired with 340B drug pricing program discount.
Modifier “TB” Drug or biological acquired with 340B drug pricing program discount, reported for informational purposes.
When applicable, providers are required to report either modifier “JG” or “TB” on OPPS claims (bill type 13X) beginning January 1, 2018. Though modifier “TB” is an informational modifier, reporting is mandatory for applicable providers.
For more information: https://www.cms.gov/Medicare/Medicare-Fee-for-Service-Payment/HospitalOutpatientPPS/Downloads/Billing-340B-Modifiers-under-Hospital-OPPS.pdf