HCPCS code Q5104: Billing guide for infliximab-abda (Renflexis)

Key Takeaways

HCPCS code Q5104 describes injection, infliximab-abda, biosimilar (Renflexis), 10 mg per billing unit, effective April 1, 2018

Unit count equals total mg administered divided by 10: a 500 mg dose requires 50 units of Q5104

CMS identifies Q5104 as a single-dose container code, making JW and JZ wastage modifiers potentially required on every claim

Practice management software like Pabau helps infusion clinics track unit calculations, modifiers, and prior authorization status for biosimilar infusions

HCPCS code Q5104 bills one unit (10 mg) of infliximab-abda, the biosimilar sold as Renflexis and administered by IV infusion under the buy-and-bill model. This guide covers the code description, unit math, required modifiers, payer-specific rules, related biosimilar codes, and documentation standards that keep infusion clinic billing workflows clean.

HCPCS code Q5104: Definition and code description

HCPCS code Q5104 identifies one billing unit of infliximab-abda, the biosimilar to reference product infliximab (J1745), marketed under the brand name Renflexis. The official descriptor from HCPCS Level II system reads: Injection, infliximab-abda, biosimilar, (renflexis), 10 mg. Each billing unit equals 10 mg of drug administered.

CMS assigned Q5104 during the Q2 2018 HCPCS update, effective April 1, 2018. It replaced the earlier Q5102 code as part of the new biosimilar payment policy, which also removed the requirement for manufacturer-identifying modifiers. Renflexis is manufactured by Organon and Samsung Bioepis and is administered by intravenous infusion. The drug falls within the TNF inhibitor/anti-inflammatory biologic class.

Sound IV therapy clinic operations require staff to distinguish the HCPCS code (Q5104) from the drug brand name (Renflexis) and from the reference product code (J1745, for originator infliximab). These are not interchangeable at the claim level.

Is Q5104 a J code or a CPT code?

Q5104 is a HCPCS Level II code, specifically a Q code, not a CPT code and not a J code. Searches for a Q5104 CPT code or a Renflexis CPT code come up often because “CPT code” gets used loosely for any billing code.

Current Procedural Terminology (CPT) codes are maintained by the American Medical Association and cover services and procedures. The HCPCS Level II Q and J codes are maintained by CMS and cover drugs and biologics like this one.

Renflexis has no separate J code. Clinicians looking for a Renflexis J code or a Q5104 J code are almost always looking for this same code. The J-code descriptor belongs to the originator, since reference infliximab (Remicade) bills under J1745. For infliximab-abda (Renflexis), Q5104 is the single drug code to report, whatever an EHR field or payer portal labels it.

Unit calculation for HCPCS code Q5104

Unit errors are the most common reason Q5104 claims are rejected without medical necessity review. The calculation is straightforward: divide the total milligrams administered by 10.

Formula: Units billed = Total mg administered / 10

Infliximab is typically dosed at 5 mg/kg for most approved indications, with rheumatoid arthritis usually dosed at 3 mg/kg. The standard schedule runs at weeks 0, 2, and 6, then every 8 weeks.

Always bill for the dose administered, not the dose ordered, and document the patient weight and calculated dose in the clinical record before submitting the claim. Claims management software that records weight-based dose calculations in the patient chart helps eliminate unit transcription errors between the clinical team and the billing department.

Louisiana Medicaid note: Humana Healthy Horizons, a Louisiana Medicaid managed-care plan, caps Q5104 reimbursement at 49 units per date of service for pediatric ulcerative colitis patients ages 6 to 8, per plan notification HUM 7651. The cap does not apply to routine adult dosing. Clinics treating pediatric UC patients under this plan should verify units against the limit before submitting.

Required modifiers when billing HCPCS code Q5104

Two modifier categories apply to Q5104 claims, and missing either one is a guaranteed edit or denial.

JW and JZ wastage modifiers

CMS identifies Renflexis (Q5104) as a single-dose container drug. That classification triggers the JW/JZ modifier requirement for Medicare Part B and most commercial payers that follow CMS policy.

• JW modifier: Append to a separate line for the discarded/wasted portion of the vial. The JW line must show the number of units wasted, not administered. It is billed at $0.00 and serves as documentation that the provider appropriately managed vial wastage.
• JZ modifier: Append to the Q5104 line when there is zero wastage (the entire vial contents were administered). This modifier confirms no wasted drug occurred and eliminates the need for a separate JW line.

For example, a 70 kg patient receiving a 5 mg/kg dose gets 350 mg, or 35 units. Four 100 mg vials are opened: 400 mg available, 350 mg administered, 50 mg discarded.

The claim includes Q5104 x 35 units administered, plus Q5104 x 5 units with the JW modifier for the 50 mg (5 units) wasted. Maintaining HIPAA-compliant documentation practices requires that wasted drug amounts are recorded in the clinical chart, not just on the claim form, to support audit requests.

Site-of-care and infusion administration codes

Q5104 is the drug code only. Infusion administration must be billed separately using the appropriate CPT infusion administration code, typically 96365 for the initial hour and 96366 for each additional hour.

The place-of-service code must match the infusion setting: office (POS 11), on-campus outpatient hospital (POS 22), or off-campus outpatient hospital (POS 19). A freestanding infusion center that is not hospital-owned typically bills POS 11; POS 19 only applies when the infusion center is a hospital-owned, off-campus department.

Mismatched place-of-service codes are a frequent Medicare audit trigger for biosimilar infusion claims. IV therapy EMR software that links the drug administration record to the claim automatically flags place-of-service discrepancies before submission.

Payer coverage rules for HCPCS code Q5104

Coverage varies meaningfully by payer type. Do not assume Medicare Part B rules apply to Medicaid or commercial plans without checking each payer’s current policy.

Medicare Part B

Medicare Part B covers Q5104 when the drug is administered in a physician office, outpatient infusion center, or hospital outpatient setting. According to Part B biosimilar guidance, reimbursement runs at ASP plus a percentage add-on, which may differ from the add-on applied to the reference product J1745.

Specific ASP payment rates change quarterly. Verify current rates through the CMS fee schedule before billing.

Prior authorization requirements under Medicare Part B depend on the specific Medicare Advantage plan if the patient is enrolled in a managed care plan. Fee-for-service Medicare does not require prior authorization for Q5104 under most circumstances, but medical necessity documentation must support the infliximab indication in the clinical record.

State Medicaid programs

State Medicaid programs set their own coverage rules. NC Medicaid billing guidelines require providers to bill Q5104 specifically for Renflexis infusions, not J1745 or other biosimilar codes. California Medi-Cal recognizes Q5104 in its injections drug manual.

Humana Healthy Horizons, a Louisiana Medicaid managed-care plan, caps Q5104 reimbursement at 49 units per date of service for pediatric ulcerative colitis patients ages 6 to 8, per notification HUM 7651. This limit does not extend to routine adult dosing or to other Louisiana Medicaid claims for Q5104.

Programs that participate in the 340B drug pricing program also expect the UD modifier on Q5104 claims for 340B-acquired drug, billed at the reduced acquisition cost. Always check the current Medicaid bulletin for the relevant state before assuming coverage policy matches Medicare.

Commercial payers

Commercial payer behavior on Q5104 is the most variable. Blue Cross Blue Shield of Michigan, for instance, has at various times designated Renflexis as a preferred or non-preferred biosimilar on its commercial formulary, which directly affects prior authorization requirements and reimbursement rates.

Prior authorization is almost universal for biosimilar infusions across commercial plans. Site-of-care requirements (office, infusion center, or hospital outpatient) also vary by plan and can determine whether Q5104 is covered at a given location.

Sound practice management software features for infusion clinics include prior authorization tracking that links each Q5104 infusion appointment to its authorization number, expiration date, and approved unit count, so staff can flag expirations before the patient arrives. This kind of tracking is central to revenue cycle management for biosimilar infusion billing.

Automate biosimilar infusion billing with Pabau

Pabau's claims management tools help infusion clinics track unit calculations, prior authorization status, and JW/JZ modifier requirements for Q5104 and other biosimilar codes, reducing clean-claim turnaround time.

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Related infliximab HCPCS codes and how Q5104 fits

Infliximab and its biosimilars occupy a cluster of HCPCS codes. Billing the wrong code for the drug administered is a compliance risk, not just an administrative inconvenience. Document the NDC on every claim so the drug dispensed can be matched to the code billed.

HCPCS code Q5121 and the other biosimilars in this table each carry their own ASP-based reimbursement rate set by CMS. Billing J1745 when the clinic dispensed Q5104 is incorrect coding and may result in overpayment recoupment if identified during a payer audit.

NCCI edits do not bundle Q5104 with J1745, so the error would typically pass claim-level edits but fail on post-payment review. Review the AAPC HCPCS code lookup when confirming the current descriptor and cross-references for any code in this cluster.

Thorough medical documentation requirements for Q5104 include recording the NDC, lot number, and vials-used count in the clinical note, not just the charge entry. This level of documentation is what supports the drug code used on the claim during a payer audit.

Documentation requirements for Q5104 infusion claims

Payers apply heightened scrutiny to biosimilar drug claims because of the cost differential compared to reference products. For Q5104, each claim should be supported by documentation that addresses four areas.

• Medical necessity: A diagnosis documented with the appropriate ICD-10-CM code supporting an FDA-approved infliximab indication: Crohn’s disease (K50.x), ulcerative colitis (K51.x), rheumatoid arthritis (M05.x–M06.x), ankylosing spondylitis (M45.x), psoriatic arthritis (L40.5x), or plaque psoriasis (L40.0). Payers require the diagnosis code to match the approved indication listed in the drug’s prescribing information.
• Drug identification: NDC, lot number, and quantity administered recorded in the clinical note or infusion record. The dispensing log from the pharmacy or in-house inventory must be available to support the vials-used count.
• Dose calculation: Patient weight (in kg), prescribed dose (mg/kg), calculated total dose (mg), and units billed. This chain of calculation must be reconstructable from the clinical record without relying on the claim form.
• Wastage documentation: If a JW modifier was appended, the chart must confirm which vials were opened, how many mg were administered, and how many mg were discarded. A timestamped infusion nurse note is the standard format most payers accept.
• Pre-treatment screening: Payers that follow CMS policy expect the record to show evaluation for latent tuberculosis before infliximab therapy starts. For rheumatoid arthritis, the note should also confirm the patient is receiving methotrexate, or explain why they cannot, along with an inadequate response to prior conventional therapy.

For plaque psoriasis claims specifically, payers expect to see ICD-10 code L40.0 supporting the infliximab-abda indication.

Using EHR integration for billing means the clinical infusion record and the charge capture system share the same data fields, so weight-based calculations documented by the nurse populate directly into the billing workflow without reentry. This eliminates the documentation-to-claim transcription errors that generate most Q5104 denials.

Structured digital intake documentation for each infusion visit ensures that every required data point is captured at the point of care, not reconstructed later from memory.

Buy-and-bill versus specialty pharmacy for Q5104

Infusion clinics that administer Renflexis under the buy-and-bill model purchase the drug from a wholesaler or specialty distributor, administer it in-office, and bill Q5104 directly to the payer. The clinic assumes inventory risk and must manage cold-chain storage requirements for the biologics on hand.

Reimbursement under buy-and-bill is typically ASP plus a percentage add-on, which can be favorable when ASP is above acquisition cost.

Under the specialty pharmacy pathway, the payer-mandated specialty pharmacy dispenses the drug directly to the patient or the infusion site. The clinic bills the infusion administration CPT codes (96365, 96366) but does not bill Q5104 since it did not purchase the drug.

Some commercial payers have shifted preferred biosimilars to a specialty pharmacy model to control drug spend. Knowing which pathway applies tells you whether Q5104 belongs on the clinic’s claim at all.

Good IV therapy intake forms capture insurance benefit verification data at the first visit, including whether the patient’s plan requires buy-and-bill or specialty pharmacy for biologics. This prevents the scenario where a clinic purchases Renflexis for a patient whose plan will not reimburse buy-and-bill drug costs.

Conclusion

HCPCS code Q5104 is a specific, high-value claim line that requires accurate unit math, mandatory wastage modifiers, NDC documentation, and payer-specific prior authorization management to reach clean payment. A single omission at any step creates a denial that takes far longer to resolve than getting it right the first time.

Pabau’s claims management tools help infusion clinics connect clinical documentation to charge capture, track biosimilar prior authorizations, and flag modifier compliance issues before submission. For clinics looking at streamlined practice management across their infusion billing workflows, book a demo to see how Pabau handles biosimilar drug claims end to end.

This week’s other new billing guides cover HCPCS code J9312 for rituximab infusions, CPT code 97124 for massage therapy, and HCPCS code A7032 for nasal mask cushions.

Continue your research

Need a structured approach to infusion clinic operations? IV therapy best practices covers clinical workflows, documentation standards, and compliance requirements for IV and infusion providers.

Looking for an EMR built for infusion therapy? IV therapy EMR software explains what to look for in a system that manages drug logs, weight-based dosing records, and billing integration.

Want to automate prior authorization tracking? Automated billing workflows shows how Pabau connects authorization status to appointment and claim records for infusion clinics.

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