C9399 HCPCS code: Unclassified drugs or biologicals
C9399 is the HCPCS Level II code for unclassified drugs or biologicals. In 2024 Medicare paid an average of $3,369.04 per service for C9399 across 772 services. Its Medicare coverage code is D (Special coverage instructions apply): Medicare covers it when its national or local coverage criteria are met. Medicare volume rose 264% from 2022 to 2024 (212 to 772 services). In 2024, about 46 clinicians billed Medicare for C9399 for 187 beneficiaries.
Code details
| Field | Value |
|---|---|
| Section | C codes — Outpatient PPS (hospital outpatient temporary codes) |
| Coverage code | D — Special coverage instructions apply |
| Pricing indicator | 53 |
| BETOS category | O1E — Other drugs |
| Added | 2004-01-01 |
| Last action effective | 2004-01-01 |
Who bills C9399 (2024)
| Measure | Value |
|---|---|
| Clinicians billing (by place of service) | 46 |
| Medicare beneficiaries | 187 |
| States with claims | 3 |
Counts only. Supplier and clinician names, contact lists and state-by-state detail are in Caduvo.
Medicare utilization for C9399, 2022–2024
| Year | Services | Beneficiaries | Avg. allowed | Avg. paid |
|---|---|---|---|---|
| 2022 | 212 | 152 | $1,620.38 | $1,296.21 |
| 2023 | 152 | 109 | $292.98 | $233.43 |
| 2024 | 772 | 187 | $4,228.49 | $3,369.04 |
States with the most C9399 services (2024)
| State | Services | Avg. paid |
|---|---|---|
| California | 509 | $2,955.81 |
| Texas | 18 | $11,161.22 |
| New York | 15 | $211.62 |
Medicare policy articles for this code
- A52451: Billing and Coding: Ranibizumab, Aflibercept and biosimilars (Wellpoint Federal (MAC - Part A, MAC - Part B))
- A55913: Billing and Coding: Hospital Outpatient Drugs and Biologicals Under the Outpatient Prospective Payment System (OPPS) (Palmetto GBA (MAC - Part A))
- A57306: Billing and Coding: Transthoracic Echocardiography (TTE) (CGS Administrators, LLC (MAC - Part A, MAC - Part B))
Covered diagnoses (1,398 ICD-10-CM codes)
The diagnoses most often listed as covered in the policy articles above:
| ICD-10-CM | Diagnosis | Articles listing it |
|---|---|---|
| A18.84 | Tuberculosis of heart | 1 |
| A36.81 | Diphtheritic cardiomyopathy | 1 |
| A39.53 | Meningococcal pericarditis | 1 |
| A40.0 | Sepsis due to streptococcus, group A | 1 |
| A40.1 | Sepsis due to streptococcus, group B | 1 |
| A40.3 | Sepsis due to Streptococcus pneumoniae | 1 |
| A40.8 | Other streptococcal sepsis | 1 |
| A40.9 | Streptococcal sepsis, unspecified | 1 |
| A41.01 | Sepsis due to Methicillin susceptible Staphylococcus aureus | 1 |
| A41.02 | Sepsis due to Methicillin resistant Staphylococcus aureus | 1 |
Showing 10 of 1,398. The full list, non-covered diagnoses and CSV export are in Caduvo.
What changed for C9399
- 2004-01-01: C9399 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 C9399?
C9399 is the HCPCS Level II code for unclassified drugs or biologicals. Short descriptor: "Unclassified drugs or biolog".
How much does Medicare pay for C9399?
In 2024, the average Medicare payment was $3,369.04 per service (average allowed $4,228.49).
Does Medicare cover C9399?
Coverage code D — Special coverage instructions apply. Medicare covers it when its national or local coverage criteria are met.
Which diagnoses support coverage for C9399?
Medicare policy articles that cite C9399 list 1,398 covered ICD-10-CM diagnosis codes across 3 articles. The most cited include A18.84 (Tuberculosis of heart), A36.81 (Diphtheritic cardiomyopathy), A39.53 (Meningococcal pericarditis). A listed diagnosis is necessary but not sufficient; the policy's other criteria still apply.
Related C93 codes
- C9300 — Injection, indigotindisulfonate sodium, 1 mg
- C9301 — Obecabtagene autoleucel, up to 400 million cd19 car-positive viable t cells, including leukapheresis and dose preparation procedures, per therapeutic dose
- C9302 — Injection, zanidatamab-hrii, 2 mg
- C9303 — Injection, zolbetuximab-clzb, 1 mg
- C9304 — Injection, marstacimab-hncq, 0.5 mg
- C9305 — Injection, nipocalimab-aahu, 3 mg
- C9306 — Injection, telisotuzumab vedotin-tllv, 1 mg
- C9349 — Puraply, and puraply antimicrobial, any type, per square centimeter
- C9352 — Microporous collagen implantable tube (neuragen nerve guide), per centimeter length
- C9353 — Microporous collagen implantable slit tube (neurawrap nerve protector), per centimeter length
- C9354 — Acellular pericardial tissue matrix of non-human origin (veritas), per square centimeter
- C9355 — Collagen nerve cuff (neuromatrix), per 0.5 centimeter length
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 C9399
- Watch C9399 for fee, coverage and descriptor changes
- Build a full Medicare revenue model for C9399
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.