On a Medicare Part B claim for a drug supplied in a single-dose vial, the JW and JZ modifiers tell CMS what happened to the contents: JW reports the units you had to discard, and JZ attests that the entire vial went into the patient with nothing left over. One of the two is required on every eligible claim line submitted on or after October 1, 2023, and claims missing the appropriate modifier can be returned as unprocessable.1Centers for Medicare & Medicaid Services. JW and JZ Modifier FAQs
Which Drugs the Modifiers Apply To
The rules cover drugs packaged in single-dose containers or single-use packages as identified on the manufacturer’s FDA-approved labeling. Once one of these vials is opened, the remainder cannot be saved for another patient, which is why CMS wants the waste tracked.
Multi-dose vials are outside the reporting mandate entirely. They contain preservatives that allow multiple needle entries, so no JW or JZ modifier goes on a claim line for a drug supplied that way. The packaging type on the label is what determines whether the rules apply, so verify it before administration.
When To Use the JZ Modifier
Use JZ when the full contents of a single-dose vial were administered and nothing was discarded. It is a positive attestation that zero waste occurred, and it has been mandatory since July 1, 2023.2Centers for Medicare & Medicaid Services. New JZ Claims Modifier for Certain Medicare Part B Drugs Leaving JZ off a no-waste claim carries the same consequence as leaving JW off a claim where waste did occur: the claim is treated as incomplete and can be returned.
When To Use the JW Modifier
Use JW whenever any portion of a single-dose vial is discarded. The medical record needs to capture three numbers at the time of service: the total amount in the vial, the amount administered, and the amount discarded. Those figures are then converted into billing units using the HCPCS code assigned to the drug.
A simple example. If the HCPCS code defines one billing unit as 1 mg and you draw 3 mg from a 5 mg vial, you administered 3 units and discarded 2 units. The 2 discarded units are reported on a separate claim line with the JW modifier attached.3Centers for Medicare & Medicaid Services. Billing and Coding: JW and JZ Modifier Billing Guidelines
Billing Units and the Rounding Rule
Fractional billing units are not allowed on Part B claims, and this creates a scenario that trips up billing staff. If the amount administered and the amount discarded together fit within a single billing unit, you report one unit on one line with the JZ modifier and do not add a JW line at all.1Centers for Medicare & Medicaid Services. JW and JZ Modifier FAQs
Say a drug’s billing unit equals 10 mg and the vial contains 10 mg. You administer 7 mg and discard 3 mg. Because the administered and discarded amounts fall inside the same billing unit, you bill one unit, JZ only. Adding a JW line for the 3 mg would double-count that unit and create an overpayment.3Centers for Medicare & Medicaid Services. Billing and Coding: JW and JZ Modifier Billing Guidelines JW only comes into play when the discarded amount represents whole billing units beyond what was administered.
How To Structure the Claim Lines
When waste qualifies for JW reporting, the claim needs two line items. The first line lists the drug’s HCPCS code with no modifier and the number of units administered. The second line repeats the same HCPCS code, adds the JW modifier, and lists only the discarded units. Each line carries its own calculated submitted charge corresponding to that line’s units.4Centers for Menter for Medicare & Medicaid Services. Billing and Coding: JW and JZ Modifier Billing Guidelines
When the entire vial was used, the claim is a single line: HCPCS code, JZ modifier, units administered.2Centers for Medicare & Medicaid Services. New JZ Claims Modifier for Certain Medicare Part B Drugs The two-line structure applies on both the CMS-1500 (professional) and UB-04 (institutional) forms, though the field layout differs.
Providers and Drugs That Are Exempt
Rural Health Clinics and Federally Qualified Health Centers do not apply JW or JZ modifiers, because drugs administered in those settings are not separately payable under Part B. Payment is bundled into the clinic’s all-inclusive or prospective payment rate for the visit, so there’s no separate drug line to modify.1Centers for Medicare & Medicaid Services. JW and JZ Modifier FAQs
Radiopharmaceuticals are not exempt. If a radiopharmaceutical is separately payable under Part B and comes in a single-dose container, the JW and JZ rules apply just as they do to any other single-dose drug. CMS has addressed this directly, so nuclear medicine claims should not be treated as carved out.1Centers for Medicare & Medicaid Services. JW and JZ Modifier FAQs
Documentation Standards
CMS does not prescribe a specific format, a location within the medical record, or a designated staff role for documenting waste. It requires accuracy: the record must reflect the correct amounts administered and discarded, and purchasing and inventory records must reconcile with what’s billed. Software-generated calculations are acceptable so long as the output is accurate.1Centers for Medicare & Medicaid Services. JW and JZ Modifier FAQs
Your local Medicare Administrative Contractor may add documentation expectations on top of the national standard, so a call to the MAC is worth making. From an audit perspective, CMS uses these modifiers to identify discarded drug amounts across the program, and reported waste that looks inconsistent with your purchasing records or patient volume shows up as a data anomaly.
What Happens if You Get It Wrong
A returned claim is the mildest outcome. Claims submitted on or after October 1, 2023, without the appropriate modifier may be returned as unprocessable until resubmitted correctly.1Centers for Medicare & Medicaid Services. JW and JZ Modifier FAQs
Systematic misreporting of administered or discarded amounts can trigger liability under the False Claims Act. As of 2025, civil FCA penalties range from $14,308 to $28,619 per false claim, plus three times the damages the government sustains, and these figures adjust annually for inflation.5Federal Register. Civil Monetary Penalties Inflation Adjustments for 2025 In a busy infusion or oncology practice, per-claim penalties stack quickly across dozens of claims a week. Enforcement in this area more often targets patterns of sloppy documentation than intentional fraud, which makes staff training on the modifier rules a straightforward investment.