HCPCS code J9173: Billing guide for durvalumab (Imfinzi)

Key Takeaways

HCPCS code J9173 describes Injection, durvalumab, 10 mg (Imfinzi); 1 billable unit equals 10 mg of drug administered.

J9173 became effective January 1, 2019, replacing the temporary C-code previously used for durvalumab claims.

JW modifier reporting has been mandatory since January 1, 2017. The JZ modifier became mandatory for dates of service on or after July 1, 2023, with claims-editing and denial enforcement beginning October 1, 2023.

Pabau’s claims management software supports structured drug billing workflows, NDC line-item reporting, and modifier tracking for oncology infusion practices.

HCPCS code J9173 is the permanent Level II code for Injection, durvalumab, 10 mg — the checkpoint inhibitor sold under the brand name Imfinzi. One billable unit equals 10 mg of drug; a 1,500 mg dose requires 150 units on the claim line.

J9173 is maintained by the Centers for Medicare and Medicaid Services (CMS) under the HCPCS Level II code set. J-codes are used for drugs administered in the physician office, infusion center, or hospital outpatient department under the buy-and-bill model.

The code became effective for dates of service on or after January 1, 2019, when CMS assigned the permanent J-code. Before that date, practices used a temporary C-code to report durvalumab claims.

Key code properties at a glance for HCPCS code J9173

Drug information: Durvalumab (Imfinzi) and FDA-approved indications

Durvalumab is a human monoclonal antibody that targets PD-L1, blocking its interaction with PD-1 and CD80 receptors. The National Cancer Institute’s SEER*Rx CanMED database classifies J9173 as Immunotherapy, Major Drug Class: Checkpoint Inhibitor, Minor Drug Class: PD-L1.

The FDA first approved durvalumab in 2017 for previously treated urothelial carcinoma under the accelerated approval pathway. AstraZeneca voluntarily withdrew that indication in February 2021 after the confirmatory DANUBE trial failed to show an overall survival benefit over chemotherapy. Durvalumab’s approved indications have since expanded well beyond bladder cancer.

Current FDA-approved indications include non-small cell lung cancer (NSCLC), small cell lung cancer (SCLC), biliary tract cancer, hepatocellular carcinoma, endometrial cancer, muscle-invasive bladder cancer, BCG-naive high-risk non-muscle-invasive bladder cancer, and resectable gastric or gastroesophageal junction (GEJ) adenocarcinoma.

Because indications continue to expand, coders should verify the current prescribing label before submitting claims. An ICD-10 diagnosis code linked to an approved indication is a prerequisite for medical necessity on most payer claims.

• Non-small cell lung cancer (NSCLC): unresectable Stage III following concurrent chemoradiotherapy; resectable NSCLC as neoadjuvant and adjuvant treatment
• Small cell lung cancer (SCLC): extensive-stage, in combination with chemotherapy; limited-stage, following concurrent chemoradiotherapy
• Biliary tract cancer: locally advanced or metastatic, in combination with gemcitabine and cisplatin
• Hepatocellular carcinoma: unresectable, in combination with tremelimumab-actl
• Endometrial cancer: primary advanced or recurrent, mismatch repair deficient (dMMR) disease (approved 2024)
• Muscle-invasive bladder cancer: neoadjuvant and adjuvant, in combination with gemcitabine and cisplatin around radical cystectomy (approved 2025)
• BCG-naive high-risk non-muscle-invasive bladder cancer: in combination with BCG (approved 2026)
• Resectable gastric or gastroesophageal junction (GEJ) adenocarcinoma: neoadjuvant and adjuvant, in combination with FLOT chemotherapy (including oxaliplatin), approved 2025

Payer prior authorization criteria often map directly to these indications. A claim submitted with a diagnosis code outside an approved indication is likely to deny on medical necessity grounds.

Practices managing multiple oncology infusion patients benefit from digital intake and billing forms that capture the treating diagnosis at the point of service, linking it to the correct ICD-10 code before the claim is built.

HCPCS code J9173 NDC crosswalk and vial sizes

Many payers require National Drug Code (NDC) numbers reported on the claim in addition to the HCPCS J-code. Imfinzi is available in two single-dose vial sizes. Both vials must be reported using J9173, but the units billed and the NDC suffix digits differ.

NDC suffix digits (“xx”) vary by lot number. Coders must use the active lot NDC at the time of billing, not a generic placeholder. The ACCC confirmed the 500 mg/10 mL vial NDC as 0310-4611-50 in its J-code announcement. Verify current active NDCs through the pharmacy dispensing system or AstraZeneca’s coding guide at the point of billing.

NDC reporting on the CMS-1500 (OMB Form 1500) follows the 11-digit format: labeler (5 digits), product (4 digits), package (2 digits), separated by hyphens (e.g., 00310-4611-50). The quantity reported alongside the NDC represents the exact number of units dispensed from that specific NDC, expressed in milliliters for liquid injectable drugs.

Practices using lab and drug management tools that integrate with dispensing records can automate this crosswalk rather than relying on manual entry. You can look up current HCPCS-NDC crosswalks using the NLM Clinical Table Search API for programmatic code lookups.

Durvalumab is one of several single-dose vial drugs with parallel NDC and JW/JZ requirements. Pabau’s guide to HCPCS code J2350 (ocrelizumab) walks through a comparable billing workflow for a different specialty infusion drug.

JW and JZ modifier requirements for J9173

CMS phased in JW and JZ modifier reporting for Part B single-dose vial drugs over several years. The JW modifier has been mandatory since January 1, 2017.

The JZ modifier became optional on January 1, 2023, then mandatory for dates of service on or after July 1, 2023. Claims-editing and denial enforcement began October 1, 2023. J9173 is explicitly listed in the CMS JW/JZ modifier policy document.

The rule is straightforward. If drug is discarded from a single-dose vial after the patient’s dose is prepared, the discarded amount is billed on a separate claim line using the JW modifier.

If no drug is discarded — the full vial is administered, or dose rounding eliminates waste — the JZ modifier is appended to attest to zero wastage. Both modifiers cannot appear together on the same line.

JW vs. JZ: Which to use and when

A practical example: a patient’s weight-based dose calculates to 1,320 mg. The practice uses three 500 mg vials (1,500 mg total). The administered dose is 132 units (1,320 mg ÷ 10 mg per unit), and the discarded amount is 18 units (180 mg).

Do not append JZ to the administered-units line — JZ is reserved for lines with zero waste. Claim line 1 should carry the 132 administered units with no modifier. Claim line 2 should carry the 18 discarded units with the JW modifier.

Drug dose rounding policies can affect whether wastage occurs. AstraZeneca’s coding guide for Imfinzi addresses dose rounding and wastage in detail. Coders should obtain and retain that guide as a desk reference.

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Medicare reimbursement and fee schedule for J9173

Medicare Part B reimburses J9173 at the Average Sales Price (ASP) plus 6%, updated quarterly by CMS. Because ASP rates change every quarter, hardcoding a dollar figure in billing reference documentation is unreliable.

The correct approach is to consult the current CMS ASP quarterly drug pricing files, published on the CMS Physician Fee Schedule lookup tool, at the start of each quarter. For a broader look at billing software options, see Pabau’s roundup of the best medical billing software in the US.

Beyond ASP, practices encounter two additional pricing benchmarks in the buy-and-bill model:

• WAC (Wholesale Acquisition Cost): the manufacturer’s list price to wholesalers. Often used as a pricing floor in commercial payer contracts.
• AWP (Average Wholesale Price): a published benchmark, historically 20-25% above WAC, used by some commercial payers as a reimbursement basis (e.g., AWP minus a contracted percentage).
• ASP (Average Sales Price): the CMS-calculated net price after rebates and discounts, updated quarterly. This is the Medicare Part B reimbursement basis for J9173.

Place of service and reimbursement differences

Reimbursement rates for J9173 vary by place of service. In the hospital outpatient department (POS 22), CMS reimburses under the Outpatient Prospective Payment System (OPPS), which assigns Ambulatory Payment Classification (APC) rates that may differ from the ASP+6% rate paid in the physician office (POS 11) or freestanding infusion center (POS 22 or 49).

Practices billing from multiple settings need to verify the applicable rate for each setting separately. For a broader view of how procedure code fee schedules work across payer types, see Pabau’s guide to procedure code fee schedules.

Infusion administration codes are billed alongside J9173 but are not bundled with it. The primary infusion code 96413 (chemotherapy infusion, up to 1 hour) and the add-on code 96415 (each additional hour) apply to the infusion service. J9173 covers the drug itself. Both are required on the same claim for a complete billing record.

Prior authorization requirements and payer coverage for J9173

Prior authorization (PA) requirements for J9173 vary substantially by payer. Medicare does not require PA for most Part B drugs billed under buy-and-bill, but Medicare Advantage plans and commercial insurers routinely do. PA requirements are not uniform across a payer’s product lines.

Common PA triggers for durvalumab claims include confirmation of histologic diagnosis, documentation of prior lines of therapy (where relevant by indication), ECOG performance status, and PD-L1 expression testing results (for NSCLC indications).

Some payers apply step therapy requirements, requiring evidence that certain first-line regimens were tried or considered before approving durvalumab. Solid HIPAA-compliant claim documentation practices keep the supporting clinical data organized and retrievable when a PA appeal is needed.

For Medicare coverage, the local coverage determination (LCD) or national coverage determination (NCD) applicable to J9173 reflects the FDA-approved indications. Practices should review payer-specific medical necessity criteria (such as those published by payers administering Prime Therapeutics or Moda Health contracts) before the first claim submission for a new patient.

Keeping these criteria on file and reviewing them at annual formulary updates reduces denial volume. Well-organized oncology practice workflows integrate PA tracking directly into scheduling so that infusion appointments are not booked without confirmed authorization.

How to bill J9173: Step-by-step workflow

Accurate J9173 billing requires coordinating drug administration records, pharmacy dispensing data, and claim construction into a single workflow. The steps below reflect the standard oncology billing sequence for a buy-and-bill drug infusion, one part of the broader healthcare revenue cycle management process that connects intake, coding, billing, and collections.

1. Confirm the dose. Check the ordered dose against the patient’s chart and the pharmacy prep record. Note exact mg given — and mg wasted, if any.
2. Calculate units. Administered mg ÷ 10 = units. So 1,200 mg = 120 units. Count any wasted units separately.
3. Record the NDC. Take the 11-digit NDC from the vial label, formatted 5-4-2 (labeler-product-package). Easiest to capture at prep time, not later.
4. Add the modifier. Wastage? Two lines — administered units (no modifier) and discarded units (JW). No wastage? Add JZ to the administered line.
5. Link the diagnosis. The ICD-10 code must match the FDA-approved indication — e.g. C34.xx for NSCLC, C22.x/C24.x for biliary tract cancer.
6. Add infusion codes. Bill 96413 for the first hour and 96415 for each extra hour — separate lines from J9173.
7. Submit and track. Watch the filing deadline and flag the claim if it doesn’t process in time. Check specifically for quantity edits, NDC mismatches, and modifier rejections.

The AAPC Codify HCPCS code lookup provides additional crosswalk data, modifier guidelines, and payer edit information for J9173. Practice management platforms with structured drug inventory tracking reduce NDC errors at the source by linking dispensing records to the claim-building module.

Conclusion

Durvalumab claims under J9173 involve more moving parts than most HCPCS J-codes: quarterly ASP rates, mandatory JW/JZ modifier reporting, NDC documentation by lot, place-of-service rate differences, and payer-specific PA criteria that require ongoing maintenance.

Pabau’s claims management software supports the structured billing workflows oncology and infusion practices need: NDC line-item capture, modifier tracking, and diagnosis-to-indication linkage built into the claim-building process. To see how Pabau handles drug billing documentation for infusion practices, book a demo with the team.

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Need help structuring oncology billing documentation? Pabau’s practice management software guide covers how integrated billing and documentation workflows reduce claim errors across specialty practices.

Billing other checkpoint inhibitors? Pabau’s HCPCS code J9299 guide covers billing for nivolumab (Opdivo), another PD-1/PD-L1 checkpoint inhibitor with similar buy-and-bill and modifier requirements.

Looking for HIPAA-compliant documentation workflows? HIPAA compliance for medical offices outlines the documentation standards that support clean oncology claim submissions.

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