Last reviewed: May 23, 2026 · CMS IOM Pub 100-04 Ch 17 · Methodology
A working reference for the HCPCS modifiers that actually appear on specialty drug claims under Medicare Part B and commercial payers. Each modifier has its own deep-dive page with decision trees, per-payer requirements, worked examples on real J-codes, denial patterns, and source citations. This hub is organized for the patient care coordinator, biller, or PA specialist who needs to ship a clean claim today.
Alphabetized by modifier code. Each entry links to the deep-dive page with payer rules, worked examples, and denial patterns.
| Modifier | Topic | Deep-dive page |
|---|---|---|
| E1 – E4 | Eyelid quadrant modifiers (upper-right, lower-right, upper-left, lower-left). Appear on ophthalmic injection claims when payer policy requires quadrant specificity. | Eye anatomic → |
| GA | ABN issued, expected denial. Patient acknowledged liability. Use when service is expected to be denied as not medically necessary and an Advance Beneficiary Notice was given. | GA / GZ / GY → |
| GY | Statutorily excluded from Medicare. Forces denial that secondary payer may pick up. Different from GZ (which is the "I should have issued the ABN" modifier). | GA / GZ / GY → |
| GZ | Expected denial, no ABN issued. Practice absorbs the cost — cannot bill the patient. Reflects an ABN-process failure. | GA / GZ / GY → |
| JC | Skin substitute used as a graft. Limited drug-billing applicability — primarily for Apligraf/Dermagraft-class products. | JC / JD / JE → |
| JD | Skin substitute used outside graft application. Reporting for wound-care drug claims. | JC / JD / JE → |
| JE | Administered via dialysate. Used on certain ESRD drug claims. | JC / JD / JE → |
| JG | 340B drug acquired under the 340B Drug Pricing Program. Required on Medicare Part B claims for 340B-acquired drugs. | JG → |
| JW | Drug amount discarded from a single-dose container. Reports the wasted units on a separate claim line. | JW → |
| JZ | Zero drug amount discarded from a single-dose container. Required on Medicare Part B claims where the dose consumed the full vial. | JZ → |
| KX | Documentation requirements specified in policy are met. Attests LCD criteria are on file. Common on immunoglobulin, growth hormone, and certain MS drug claims. | KX → |
| LT / RT | Left / right anatomic side. Bilateral intravitreal injections report two lines (one LT, one RT), not modifier 50. | Eye anatomic → |
| TB | 340B alternative used by some state Medicaid programs in place of JG. Apply per the payer's published guidance. | TB → |
| (suffix) | Biosimilar identification convention. Each biosimilar has its own HCPCS code; no separate "biosimilar modifier" exists. The informally used "JR" is not a real HCPCS modifier. | Biosimilar suffix → |
Common biller scenarios and the modifier the claim line needs. Click through for the full deep-dive.
Pediatric or weight-based dose that doesn't consume the full vial. Documented waste.
→ Two claim lines. Line 1: J9271 × 60 units (no waste modifier). Line 2: J9271 × 40 units with JW.
Whole-vial dose with zero discarded amount on a Medicare Part B claim.
→ One claim line with JZ. Required since CMS began enforcing in 2024.
Drug was sourced through the 340B Drug Pricing Program; claim is reimbursed under standard Part B rules.
→ Append JG to the J-code line. Some state Medicaid programs require TB instead — check payer guidance.
Intravitreal injections in both eyes during the same visit.
→ Two claim lines for the J-code and CPT 67028. One with RT, one with LT. Not modifier 50.
Local Coverage Determination specifies that supporting documentation must be on file and that the claim attests to it.
→ Append KX to the J-code line. Missing KX denies as missing documentation.
You issued an ABN and the patient signed it.
→ Append GA. If you should have issued an ABN but didn't, GZ (practice cannot bill the patient). If the service is statutorily excluded entirely, GY.
Summary of the top five payers' positions on each modifier covered here. Deep-dive pages have the full payer-by-payer rules, fax numbers, and appeal language.
| Modifier | Medicare | UnitedHealthcare | Aetna | Cigna | Humana |
|---|---|---|---|---|---|
| JW | Required | Required | Required | Required | Required |
| JZ | Required | Required | Required | Recommended | Required (MA) |
| JG | Required (340B Part B) | Per policy | Per policy | Per policy | Per policy |
| TB | N/A | N/A | N/A | N/A | N/A (Medicaid only) |
| KX | LCD-driven | Per medical policy | Per medical policy | Per medical policy | LCD-driven (MA) |
| GA / GZ / GY | Required (ABN) | N/A (commercial) | N/A (commercial) | N/A (commercial) | Required (MA) |
| RT / LT | Required (per eye) | Required (per eye) | Required (per eye) | Required (per eye) | Required (per eye) |
| E1 – E4 | Per LCD | Per medical policy | Per medical policy | Per medical policy | Per medical policy |
"Required" means a missing modifier triggers a hard reject on most claim lines for that payer. "Per policy" means commercial medical-policy bulletins drive line-level behavior; check the deep-dive page for the bulletin reference. "N/A" means the modifier does not apply to that payer's benefit channel.
Append JW to a separate claim line that reports the discarded units. Bill the administered units on a different line with no waste modifier. JW and JZ are mutually exclusive on a single line.
Yes for Medicare Part B since the CMS edit cycle began enforcing in mid-2024. Commercial payer alignment varies; UHC, Aetna, Cigna, and Humana have largely followed the Medicare convention but a small number of legacy adjudication systems still warn-and-pass rather than reject.
JG indicates a 340B-acquired drug billed on a Medicare Part B claim. TB is the informational modifier some Medicaid programs require on 340B drugs that bypass the standard 340B-claim flag. Apply per the payer's published guidance — Medicare uses JG; some state Medicaid programs require TB.
Two claim lines with RT and LT respectively, not modifier 50. Intravitreal injections (CPT 67028) are reported per eye, not as a bilateral procedure.
No. Biosimilar product identification on Part B claims uses the biosimilar-specific HCPCS code (which the manufacturer suffix maps to), not a separate modifier. The "JR" shorthand sometimes used informally is not a recognized HCPCS Level II modifier.
KX attests that the documentation supporting medical necessity for the specific LCD is on file. Common on immunoglobulin, growth hormone, and certain MS drug claims where the MAC LCD specifies KX as the attestation mechanism. Without KX on a KX-required line, the claim denies as missing required documentation.
GA — ABN was issued and the patient acknowledged liability. GZ — service is expected to be denied and no ABN was issued (practice absorbs the cost). GY — item is statutorily excluded from Medicare. The three are not interchangeable; GA and GZ are about the ABN process, GY is about the coverage category.
CMS modifier rules change every year. Manufacturer refund rules under Section 1847A(h) of the Social Security Act started enforcing in 2024 and have continued to evolve. Payer policies layer on top — one payer may require KX where another doesn't. We update this reference quarterly against the CMS Internet-Only Manuals and the MLN Matters articles, and on an event-driven basis when a payer policy or rule change crosses our reader-feedback channel. The CareCost editorial team reviews each modifier page on publication and on each material update; the full process is in the Editorial Policy.