Summary & Overview
HCPCS M1145: MFN Model Drug Add-On Amount, Per Dose
HCPCS Level II code M1145 designates a per-dose add-on amount tied to the Most Favored Nation (MFN) drug pricing model. It captures an additional per-dose payment associated with drugs subject to the MFN pricing framework and is intended to be reported on relevant drug administration claims; the descriptor explicitly excludes billing with line items carrying the jw modifier. Nationally, this code matters because it affects reimbursement reporting for certain high-cost or specialty drugs administered in outpatient settings and can influence provider revenue and payor adjudication for those doses.
Key payers in this coverage set include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of what the code represents, the typical sites of service where it applies, and which major payers are considered in national coverage discussions. The publication outlines benchmarks and policy context relevant to billing and claims processing for drug add-on payments, summarizes common modifiers associated with drug administration that may appear elsewhere in claims, and flags areas where input data were not provided. Data not available in the input are noted where applicable.
Billing Code Overview
HCPCS Level II code M1145 describes a most favored nation (mfn) model drug add-on amount, billed per dose. This add-on is intended to be reported on claims to capture an additional per-dose payment tied to drugs priced under an mfn model. The descriptor specifies that it should not be billed on line items that carry the jw modifier.
Service type: Drug administration/add-on payment for a drug dose.
Typical site of service: Outpatient infusion or injection settings where drug doses are administered and billed separately, including hospital outpatient departments and physician office infusion centers.
Clinical & Coding Specifications
Clinical Context
A patient receiving an infused, Medicare Part B–covered prescription biologic at an outpatient infusion center is charged an additional per-dose payment under the Most Favored Nation (MFN) model. For example, a 67-year-old patient with rheumatoid arthritis presents to an ambulatory infusion suite for a scheduled intravenous biologic medication. The facility documents the drug administration, records the specific drug NDC and dose, and bills the drug itself on the line item. Separately, the facility appends the HCPCS Level II add-on code M1145 to capture the MFN model add-on amount per dose when applicable. The clinical workflow includes verifying coverage and MFN applicability, ensuring the drug line does not carry the JW (drug discarded/not administered) modifier, recording infusion administration details in the medical record (start/stop times, lot number, dose), and submitting a clean claim with appropriate facility or professional identifiers. Typical sites of service are outpatient hospital infusion centers, physician office infusion suites, and ambulatory surgical centers where parenteral biologics or specialty injectables are administered and reimbursed under Medicare Part B or commercial payors adopting MFN payment adjustments.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
22 | Increased procedural services |