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HCPCS Q5121 · Level II · Part B drug

HCPCS Q5121: Injection, infliximab-axxq, biosimilar, (avsola), 10 mg

Reviewed by QuickIntell RCM Editorial Team · Last reviewed

Data effective
Data currency: ASP payment limits October 2026 (effective October 1, 2026); MUE and NCCI edits 2026 Q4 (effective October 1, 2026); OPPS Addendum B July 2026 (effective July 1, 2026). Next CMS release: January 1, 2027 (ASP, MUE, NCCI and OPPS quarterly updates).

Key facts for Q5121

Billing unit
10 MG
Inj. avsola, 10 mg
ASP payment limit
$34.686
October 2026; +12.5% vs July 2026
Practitioner MUE
150
MAI 3
OPPS status
SI K
APC 9381
NCCI exposure
no PTP pairs
Coverage articles
1
5 states

TL;DR

HCPCS Q5121 is the Level II code for Injection, infliximab-axxq, biosimilar, (avsola), 10 mg, billed per 10 MG. The Medicare Part B ASP payment limit for October 2026 is $34.686 per billing unit, up 12.5% from July 2026. The practitioner MUE allows up to 150 units per date of service (MAI 3). Under OPPS it carries status indicator K in APC 9381. As a biosimilar it has its own code and ASP; the reference product cannot be billed under this code, and the JZ or JW modifier rules for discarded amounts apply per single-dose vial. The 10 mg billing unit means doses are reported in multiples of ten milligrams, with any remainder rounded per contractor policy; mismatched units against the NDC quantity trigger MUE and NDC-unit edits. The ASP crosswalk maps 2 NDCs to it, sold as Avsola by Amgen Inc. 1 Medicare coverage article lists the code across 5 states, including .

Medicare Part B payment limit (ASP)

CMS sets the Part B payment limit for Q5121 at $34.686 per 10 MG for October 2026, derived from manufacturer average sales price plus 6%, compared with $30.83 in July 2026. Beneficiary coinsurance is 20%.

ASP payment limits for Q5121
QuarterPayment limitPerCoinsurance
October 2026$34.68610 MG20%
July 2026$30.8310 MG—
Source: CMS Medicare Part B Drug Payment Limit File. Commercial and Medicaid payers set their own rates.

NDC to HCPCS billing-unit conversion

The October 2026 ASP crosswalk maps 2 NDCs from 1 labeler to Q5121. Report the NDC in the claim's drug segment and bill the number of Q5121 units that equals the quantity administered divided by 10 MG; the last column gives units per full package.

NDCs that crosswalk to Q5121
NDCDrug nameLabelerPackage sizeBilling units / package
55513-0670-01AvsolaAmgen Inc1 × 110
55513-0670-21AvsolaAmgen Inc1 × 110

Medically Unlikely Edits (MUE)

CMS publishes 2 MUE values for Q5121. For practitioners the limit is 150 units per date of service with adjudication indicator 3, a date-of-service clinical edit: units above the limit deny but can be paid on appeal with documentation that the quantity was medically reasonable.

MUE values for Q5121 by setting
SettingMUE (units/DOS)MAICMS rationale
Practitioner services1503 Date of Service Edit: ClinicalPrescribing Information
Facility outpatient hospital1503 Date of Service Edit: ClinicalPrescribing Information

NCCI edits and add-on relationships

No active practitioner PTP pair lists Q5121 as a column-1 or column-2 code in v323r0. Drug supply codes are rarely bundled; the administration codes billed with them are where PTP edits usually apply.

Q5121 is neither an add-on code nor a designated primary code in the 2026 Q4 NCCI add-on edit file.

Medicare coverage articles

1 current Medicare Administrative Contractor article lists Q5121 in their HCPCS tables, covering 5 states. Each article carries the covered and non-covered ICD-10 codes that medical-necessity denials (CARC 50) are adjudicated against.

Billing and Coding Articles listing Q5121
ArticleTitleContractor(s)StatesRelated LCD
Billing and Coding: Infliximab and biosimilarsWellpoint FederalCT IL MN NY WIL33394

Hospital outpatient (OPPS) status

In the July 2026 OPPS Addendum B, Q5121 carries status indicator K and is assigned to APC 9381, with a published national unadjusted payment of $30.83. Status K means the drug is paid separately under OPPS at the ASP-based rate rather than packaged into the procedure.

Common denials for Q5121 and how to prevent them

CARC 16 · M119

NDC missing, invalid or not matched to the HCPCS code

CARC 151 · N362

units billed exceed the MUE for the date of service

CARC 50 · N115

diagnosis not covered by the applicable coverage article or LCD

How QuickIntell checks Q5121 before the claim leaves

QuickCode validates the NDC-to-unit conversion against the current ASP crosswalk, checks units against every published MUE setting and flags PTP and add-on conflicts on the same claim. QuickRCM routes CARC 16, 151 and 50 denials on drug lines with the matching coverage article attached so the appeal starts with evidence.

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Frequently asked questions — HCPCS Q5121

What does HCPCS code Q5121 describe?

Q5121 is defined by CMS as "Injection, infliximab-axxq, biosimilar, (avsola), 10 mg". Each billing unit represents 10 MG, so the units reported on the claim must equal the dose administered divided by that unit.

What is the Medicare reimbursement for Q5121 in October 2026?

The ASP-based payment limit is $34.686 per 10 MG, with 20% beneficiary coinsurance. Medicare Administrative Contractors apply this limit; commercial payers use their own fee schedules. The July 2026 limit was $30.83.

How many units of Q5121 can be billed per day?

The practitioner Medically Unlikely Edit is 150 units per date of service with adjudication indicator 3 (3 Date of Service Edit: Clinical). MAI 3 edits can be appealed with documentation that the units were medically reasonable. CMS cites "Prescribing Information" as the rationale.

Which NDCs map to Q5121?

The October 2026 ASP crosswalk lists 2 NDCs from 1 labeler: Avsola (Amgen Inc). For example NDC 55513-0670-01 is a 1 package equal to 10 billing units. The crosswalk's billing-units-per-package figure converts each package into Q5121 units.

Does Q5121 have NCCI bundling edits?

No active practitioner PTP pairs list Q5121 as a column-1 or column-2 code in the v323r0 release. Unit limits (MUE) and medical-necessity coverage rules still apply.

Which Medicare coverage articles mention Q5121?

1 current Billing and Coding Article in the Medicare Coverage Database list Q5121, covering 5 states: (Billing and Coding: Infliximab and biosimilars).

Sources

Every figure on this page is taken from the CMS publications below, as released by the Centers for Medicare & Medicaid Services. Projection built 2026-10-02. Verify against the primary file before billing or contracting decisions.

Disclaimer

This page is an operational reference compiled from CMS publications: the Medicare Part B drug payment limit and NDC crosswalk files, NCCI MUE and add-on edit tables, aggregate PTP statistics, OPPS Addendum B and the Medicare Coverage Database. Payment limits are Medicare national amounts; commercial and Medicaid payers differ. CPT codes are shown as numbers only; CPT descriptors are copyright AMA. Nothing here is legal, clinical or billing advice.