Q5123 HCPCS code: Injection, rituximab-arrx, biosimilar, (riabni), 10 mg
Q5123 is the HCPCS Level II code for injection, rituximab-arrx, biosimilar, (riabni), 10 mg. In 2024 Medicare paid an average of $31.47 per service for Q5123 across 1,769,715 services. Its Medicare coverage code is C (Carrier judgment): Coverage is decided by the Medicare contractor (MAC) case by case. The NCCI unit limit is 150 per day on outpatient hospital claims. Medicare volume rose 324% from 2022 to 2024 (416,982 to 1,769,715 services). In 2024, about 2,447 clinicians billed Medicare for Q5123 for 6,258 beneficiaries; Florida, California, Texas accounted for 42% of services.
Code details
| Field | Value |
|---|---|
| Section | Q codes — Temporary codes |
| Coverage code | C — Carrier judgment |
| Pricing indicator | 51 — Drug or biological (priced per ASP/average sales price rules) |
| BETOS category | O1D — Chemotherapy |
| Added | 2021-07-01 |
| Last action effective | 2021-07-01 |
Who bills Q5123 (2024)
| Measure | Value |
|---|---|
| Clinicians billing (by place of service) | 2,447 |
| Medicare beneficiaries | 6,258 |
| States with claims | 42 |
| Share of services in top 3 states (Florida, California, Texas) | 42% |
Counts only. Supplier and clinician names, contact lists and state-by-state detail are in Caduvo.
Medicare utilization for Q5123, 2022–2024
| Year | Services | Beneficiaries | Avg. allowed | Avg. paid |
|---|---|---|---|---|
| 2022 | 416,982 | 1,481 | $54.64 | $43.61 |
| 2023 | 625,590 | 2,719 | $43.82 | $34.90 |
| 2024 | 1,769,715 | 6,258 | $39.51 | $31.47 |
States with the most Q5123 services (2024)
| State | Services | Avg. paid |
|---|---|---|
| Florida | 406,770 | $31.68 |
| California | 185,920 | $31.33 |
| Texas | 148,939 | $31.32 |
| Tennessee | 114,115 | $31.69 |
| Arkansas | 80,312 | $31.61 |
NCCI unit limits (MUE)
| Claim type | Max units per day | Rationale |
|---|---|---|
| outpatient hospital claims | 150 | Prescribing Information |
| practitioner claims | 150 | Prescribing Information |
Medicare policy articles for this code
- A55639: Billing and Coding: Chemotherapy Agents for Non-Oncologic Conditions (WPS Insurance Corporation (MAC - Part A, MAC - Part B))
- A56380: Billing and Coding: Rituximab (Palmetto GBA (MAC - Part A, MAC - Part B))
- A59101: Billing and Coding: Off-label Use of Rituximab and Rituximab Biosimilars (Wellpoint Federal (MAC - Part A, MAC - Part B))
Covered diagnoses (1,182 ICD-10-CM codes)
The diagnoses most often listed as covered in the policy articles above:
| ICD-10-CM | Diagnosis | Articles listing it |
|---|---|---|
| D47.Z1 | Post-transplant lymphoproliferative disorder (PTLD) | 3 |
| D59.0 | Drug-induced autoimmune hemolytic anemia | 3 |
| D59.11 | Warm autoimmune hemolytic anemia | 3 |
| D59.12 | Cold autoimmune hemolytic anemia | 3 |
| D59.13 | Mixed type autoimmune hemolytic anemia | 3 |
| D59.19 | Other autoimmune hemolytic anemia | 3 |
| D68.4 | Acquired coagulation factor deficiency | 3 |
| D69.3 | Immune thrombocytopenic purpura | 3 |
| D69.41 | Evans syndrome | 3 |
| D69.42 | Congenital and hereditary thrombocytopenia purpura | 3 |
Showing 10 of 1,182. The full list, non-covered diagnoses and CSV export are in Caduvo.
What changed for Q5123
- 2021-07-01: Q5123 added to HCPCS Level II
- Next scheduled CMS quarterly update (HCPCS and DMEPOS fee schedule): 2027-01-01
Frequently asked questions
What is HCPCS code Q5123?
Q5123 is the HCPCS Level II code for injection, rituximab-arrx, biosimilar, (riabni), 10 mg. Short descriptor: "Inj. riabni, 10 mg".
How much does Medicare pay for Q5123?
In 2024, the average Medicare payment was $31.47 per service (average allowed $39.51).
Does Medicare cover Q5123?
Coverage code C — Carrier judgment. Coverage is decided by the Medicare contractor (MAC) case by case.
Which diagnoses support coverage for Q5123?
Medicare policy articles that cite Q5123 list 1,182 covered ICD-10-CM diagnosis codes across 3 articles. The most cited include D47.Z1 (Post-transplant lymphoproliferative disorder (PTLD)), D59.0 (Drug-induced autoimmune hemolytic anemia), D59.11 (Warm autoimmune hemolytic anemia). A listed diagnosis is necessary but not sufficient; the policy's other criteria still apply.
How many units of Q5123 can be billed per day?
150 on outpatient hospital claims; 150 on practitioner claims (NCCI medically unlikely edits).
Related Q51 codes
- Q5100 — Injection, ustekinumab-kfce (yesintek), biosimilar, 1 mg
- Q5101 — Injection, filgrastim-sndz, biosimilar, (zarxio), 1 microgram
- Q5102 — Injection, infliximab, biosimilar, 10 mg
- Q5103 — Injection, infliximab-dyyb, biosimilar, (inflectra), 10 mg
- Q5104 — Injection, infliximab-abda, biosimilar, (renflexis), 10 mg
- Q5105 — Injection, epoetin alfa-epbx, biosimilar, (retacrit) (for esrd on dialysis), 100 units
- Q5106 — Injection, epoetin alfa-epbx, biosimilar, (retacrit) (for non-esrd use), 1000 units
- Q5107 — Injection, bevacizumab-awwb, biosimilar, (mvasi), 10 mg
- Q5108 — Injection, pegfilgrastim-jmdb (fulphila), biosimilar, 0.5 mg
- Q5109 — Injection, infliximab-qbtx, biosimilar, (ixifi), 10 mg
- Q5110 — Injection, filgrastim-aafi, biosimilar, (nivestym), 1 microgram
- Q5111 — Injection, pegfilgrastim-cbqv (udenyca), biosimilar, 0.5 mg
Building a device that would bill under a code like this? Caduvo matches a device description to HCPCS/CPT codes, Medicare coverage and payment, and the FDA pathway in one report.
Next steps
- Run a reimbursement report for a device billed under Q5123
- Watch Q5123 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for Q5123
Sources: CMS HCPCS Level II release October 2025; CMS DMEPOS fee schedule; CMS NCCI MUE tables; CMS Medicare utilization (physician and DME supplier files); CMS Medicare Coverage Database articles. Fees are Medicare allowables, not commercial rates. Not billing or legal advice.