C9304 — Injection, marstacimab-hncq, 0.5 mg
C9304 is a HCPCS Level II code for injection, marstacimab-hncq, 0.5 mg. It belongs to the Outpatient Prospective Payment System section. It was terminated on June 30, 2025 and is not valid on new claims.
This code has been terminated
CMS terminated C9304 on June 30, 2025. It stays in the file as history — a claim you are auditing from before that date may legitimately carry it — but it must not appear on a new claim. The adjacent codes below are the usual place to look for its replacement.
Medicare coverage: Special coverage instructions apply
There are published conditions attached to this code. Check the applicable coverage policy before billing it: the code being valid is not the same as the service being covered.
From the coverage field of the CMS Alpha-Numeric HCPCS File, release 2026Q3-Jul. This states Medicare’s position on the code, not on your particular claim.
The CMS record for C9304
- Long descriptor
- Injection, marstacimab-hncq, 0.5 mg
- Short descriptor
- Inj marstacimab, 0.5 mg
- Added
- April 1, 2025
- Terminated
- June 30, 2025
- BETOS
- O1E
- Pricing indicator
- 53 — Other
The official wording. This is what the code means.
CMS's 28-character form, which is what shows up on a remittance advice.
When CMS introduced the code.
When CMS retired it.
Berenson-Eggers Type of Service — CMS's own analytic grouping.
Statute.
Codes adjacent to C9304
HCPCS has no hierarchy — related items simply sit next to each other in the numbering. If C9304 is not quite right, the correct code is very often within a few positions of it.
- C9275Injection, hexaminolevulinate hydrochloride, 100 mg, per study doseterminated
- C9285Lidocaine 70 mg/tetracaine 70 mg, per patch
- C9290Injection, bupivacaine liposome, 1 mgterminated
- C9293Injection, glucarpidase, 10 units
- C9300Injection, indigotindisulfonate sodium, 1 mgterminated
- C9301Obecabtagene autoleucel, up to 400 million cd19 car-positive viable t cells, including leukapheresis and dose preparation procedures, per therapeutic doseterminated
- C9302Injection, zanidatamab-hrii, 2 mgterminated
- C9303Injection, zolbetuximab-clzb, 1 mgterminated
- C9305Injection, nipocalimab-aahu, 3 mgterminated
- C9306Injection, telisotuzumab vedotin-tllv, 1 mgterminated
- C9307Injection, linvoseltamab-gcpt, 1 mgterminated
- C9308Injection, carboplatin (avyxa), 1 mgterminated
- C9309Injection, onasemnogene abeparvovec-brve, per treatmentterminated
- C9310Injection, leucovorin calcium (avyxa), 1 mg
- C9349Puraply, and puraply antimicrobial, any type, per square centimeterterminated
- C9352Microporous collagen implantable tube (neuragen nerve guide), per centimeter length
Questions about C9304
What is HCPCS code C9304?
C9304 is a HCPCS Level II code for injection, marstacimab-hncq, 0.5 mg. It sits in the Outpatient Prospective Payment System section.
Does Medicare cover C9304?
The CMS HCPCS file marks C9304 as "Special coverage instructions apply". There are published conditions attached to this code. Check the applicable coverage policy before billing it: the code being valid is not the same as the service being covered.
Is C9304 still valid?
No. C9304 was terminated on June 30, 2025 and should not be used on new claims.