Administration codes, modifiers, benefit routing and unit math for infused and injected drugs.
Specialty drug claims carry two halves: a J-code that identifies the drug and its billing units, and a CPT code that identifies the administration. Get either half wrong — the unit basis, a missing JW line, the wrong benefit — and the claim is denied or underpaid. These pages are the reference we maintain for both halves, sourced from the CMS ASP file, HCPCS descriptors and published payer policy.
Four explainers cover the concepts the code-level pages assume you already know.
| Page | What it answers |
|---|---|
| Buy-and-bill → | How a practice acquires, administers, and bills a drug it purchased itself — and where the margin actually sits. |
| Medical vs pharmacy benefit → | Which benefit a drug bills under, how to check, and what changes on the claim when it flips. |
| White, brown and clear bagging → | What changes on the claim when the payer supplies the drug — and which billing options disappear. |
| Billing glossary → | Plain definitions for ASP, WAC, J-code, JW/JZ, site of care, accumulator, and the rest. |
The most common way a specialty drug claim goes wrong is the unit conversion. Billing units come from the HCPCS descriptor, not the vial size and not the milligrams administered — Aranesp and Neupogen are microgram-based, so a milligram assumption is off by a factor of a thousand. The infusion billing units calculator converts a dose into billable units, resolves the vial combination, and separates the administered amount from any discarded amount — which is what determines whether the drug line carries a JW report of the discarded units or a JZ attestation that none were.
Which administration code applies depends on route, whether the drug is chemotherapeutic, and the sequence of services in the encounter. Full decision tree, hour-counting rules and NCCI bundling edits on the CPT administration codes hub.
| CPT code(s) | What it reports |
|---|---|
| 96360-96361 → | Hydration IV infusion |
| 96365-96366 → | Therapeutic IV infusion, initial and additional hours |
| 96369-96371 → | Subcutaneous infusion |
| 96372 → | Therapeutic IM/SC injection |
| 96374-96376 → | IV push, initial and sequential |
| 96401-96402 → | Chemo IM/SC administration |
| 96409-96411 → | Chemo IV push |
| 96413-96415 → | Chemo IV infusion, initial and additional hours |
| 96417 → | Chemo IV infusion, each additional sequential |
| 67028 → | Intravitreal injection |
Modifiers carry the facts the code itself cannot: discarded drug, 340B acquisition, medical necessity, laterality. Full reference and payer divergence on the billing modifiers hub.
| Modifier | What it reports |
|---|---|
| JW → | discarded drug amount |
| JZ → | zero discarded amount |
| JG → | 340B-acquired drug |
| TB → | 340B, informational |
| KX → | requirements met |
| GA / GZ / GY → | ABN and liability |
| JC / JD / JE → | skin substitute and dialysis |
| Biosimilar suffixes → | Biosimilar suffixes |
| RT / LT and eye anatomic modifiers → | RT / LT and eye anatomic modifiers |
Every drug we cover has its own page with the J-code, billing-unit basis, vial sizes, covered diagnoses and payer notes. Browse the drug billing index, or see Medicare Part B coverage and payer prior-authorization playbooks.
Start with buy-and-bill, which explains the claim lifecycle end to end, then read medical vs pharmacy benefit to learn which claims route where. The glossary defines every term used across these pages.
The J-code (or Q-code) identifies the drug and its billing units. The CPT administration code identifies the work of giving it — the infusion or injection itself. Nearly every specialty drug claim carries both, and they are priced on different fee schedules.
Billing units come from the HCPCS descriptor, not the vial size or the milligrams administered. Our free billing units calculator converts a dose into billable units and splits administered from discarded amounts for JW and JZ reporting.
No. These pages cover coding rules, Medicare published rates, and payer policy that is public record. What a specific patient owes under a specific plan depends on that plan’s negotiated rates and the patient’s benefit design — that is what the CareCost estimator is for.
CareCost Estimate parses payer and Medicare pricing data for infusion practices. These reference pages exist because the coding rules are public but scattered across HCPCS descriptors, the quarterly CMS ASP file, MAC articles and individual payer policies. Unit bases and vial sizes are bound to the current CMS ASP Drug Pricing file and its NDC-HCPCS crosswalk; payer rules cite the payer's own published policy. Corrections: report an error.