JW vs JZ Decision Chart
For Medicare Part B drugs from single-dose containers. Answer three questions, in order. When you need the units calculated, use the JW & JZ modifier calculator.
| Step | Question | If YES | If NO | Source |
|---|---|---|---|---|
| 1 | Did the drug come from a single-dose container? | Go to step 2. | Neither modifier. Bill the administered units only — JW/JZ never apply to multi-dose vials. | CMS Claims Processing Manual Ch. 17 §40 |
| 2 | Was any of the drug discarded? | Go to step 3. | Append -JZ to the single administered line (attests zero waste). | CMS Change Request 13056 (MLN Matters MM13056) |
| 3 | Is the discarded amount at least one full HCPCS billing unit? | Two lines: administered units with no modifier, plus discarded units with -JW. | Append -JZ to the administered line. Sub-unit waste is never billed with -JW. | CMS JW/JZ Modifier FAQ (incl. sub-unit rule and Q15 worked case) |
Before you submit
- Convert milligrams to units with the HCPCS descriptor unit size first — units come from the code descriptor, never from vial size.
- The chart record should show the vial size opened, the amount administered and the amount discarded, so the JW line can be audited back to the vial.
- Different drugs on the same claim are decided separately — one drug can be -JW while another is -JZ.
- Medicare Advantage and commercial plans usually follow this CMS convention, but that is plan policy: check the payer's drug-wastage rules before billing either modifier off Medicare.
Sources (checked 2026-10-23, re-verified every November): CMS Change Request 13056 / MLN Matters MM13056; CMS JW/JZ Modifier FAQ (hospital outpatient PPS); CMS Medicare Claims Processing Manual, Chapter 17, Section 40. Full working with your own vial sizes: JW & JZ drug waste calculator. Related: NDC 10 to 11 digit converter for the same claim.