HCPCS Code S9379: Home infusion therapy billing guide

Key Takeaways

HCPCS Code S9379 is the catch-all NOC per diem code for home infusion therapies that lack a specific S9325-S9379 HCPCS code.

S9379 bundles administrative services, professional pharmacy services, care coordination, and all necessary supplies and equipment into one daily rate.

Drugs and nursing visits are always coded separately with J-codes and nursing visit codes – never bundle them into S9379.

S9379 is not payable by Medicare; it is used primarily with commercial payers and Medicaid managed care plans that accept NHIA coding standards.

HCPCS Code S9379 is the not otherwise classified (NOC) per diem code for home infusion therapy — the catch-all for any infusion service that has no dedicated HIT code in the S9325–S9379 range. Using it correctly requires understanding what the code bundles, what must be billed separately, and which payers accept it.

Home infusion providers encounter S9379 most often when treating patients with complex medication regimens that fall outside standard hydration, antibiotic, or chemotherapy protocols. This guide covers the full descriptor, bundling rules, payer coverage, related codes, and documentation requirements for clean S9379 claims.

Providers billing other injectable or infused drugs may also need to reference codes such as HCPCS code J1559 for Hizentra injection or HCPCS code J9173 for durvalumab (Imfinzi) when those specific drugs are administered.

What HCPCS Code S9379 covers per diem

The official full descriptor for S9379, as maintained by the Centers for Medicare and Medicaid Services (CMS), reads: Home infusion therapy, infusion therapy, not otherwise classified; administrative services, professional pharmacy services, care coordination, and all necessary supplies and equipment (drugs and nursing visits coded separately), per diem.

Breaking that descriptor into its components makes the bundling logic clear. Every unit of S9379 billed for a single calendar day includes all four of the following service categories.

• Administrative services: Intake processing, insurance verification, prior authorization management, claims submission, and patient scheduling overhead associated with delivering the infusion program.
• Professional pharmacy services: Compounding, labeling, dispensing, and clinical pharmacist review of the prescribed infusion medication and related drug therapy monitoring.
• Care coordination: Communication between the dispensing pharmacy, prescribing physician, nursing agency, and the patient to ensure continuity of the infusion program at home.
• All necessary supplies and equipment: IV tubing, dressings, alcohol wipes, infusion pumps, and any durable medical equipment (DME) required to administer the infusion in the home setting.

Two categories are explicitly excluded from the per diem bundled rate: the drug itself and nursing visits. Both must be coded separately; billing them inside S9379 is a compliance error that can trigger claim denials or audit liability. This unbundling requirement is a core competency for billing staff.

For wearable or durable medical equipment billed alongside home infusion services, see the HCPCS code K0606 wearable defibrillator billing guide, the HCPCS code E0570 nebulizer billing guide, and the HCPCS code L0642 lumbar orthosis billing guide for parallel DME coding considerations.

When S9379 applies vs. a specific HIT code

S9379 is a last-resort code. Before assigning it, confirm no specific HIT code covers the infusion being provided. The HCPCS S9325–S9379 range includes individual per diem codes for hydration therapy, antibiotic infusion, antifungal therapy, antiviral therapy, chemotherapy, and several other categories. S9379 applies only when the prescribed infusion falls outside every one of those named categories.

The National Home Infusion Association (NHIA) National Coding Standard confirms this: “The general code S9379 is used for NOC infusion therapies (including NOC administration through an IV line).”

Practical examples where S9379 is appropriate include biologics administered at home for conditions such as ankylosing spondylitis (ICD-10 code M45.2) or mononeuropathy in diseases classified elsewhere (ICD-10 code G59) when no specific HIT code applies, along with experimental or off-label IV protocols and combination therapies where the primary drug does not map to any existing HIT descriptor.

S9379 payer coverage: Medicare, Medicaid, and commercial plans

Coverage for S9379 varies significantly by payer. Billing teams must verify eligibility for each patient before submitting a claim, as blanket assumptions about coverage will generate denials.

The Medicare exclusion is absolute: HCPCS Code S9379 is not payable by Medicare. S-series codes are maintained by commercial payers and state Medicaid programs, not by Medicare. Submitting S9379 to Medicare fee-for-service will result in an automatic denial.

Providers who also see Medicare patients running infusion therapy at home need separate coverage arrangements, typically through Medicare Advantage plans that may or may not mirror commercial coding policies.

For providers navigating HIPAA compliance for medical offices, keep in mind that the NHIA National Coding Standard was developed specifically for HIPAA-compliant electronic claim transactions. Using S9379 in accordance with NHIA guidelines satisfies the transaction standard requirements when submitting to payers that accept S-codes.

Prior authorization requirements

Because S9379 covers NOC therapies, most commercial payers treat it as high-risk for overuse and require prior authorization before the infusion program begins. Authorization requirements vary by plan.

UnitedHealthcare’s commercial home infusion policy, for example, lists S9379 among covered home infusion codes but requires PA and clinical documentation justifying the NOC designation before coverage is approved. Blue Cross Blue Shield plans follow similar protocols, though the specific criteria and look-back periods differ by state and plan tier. Always obtain written PA before the first infusion day.

What is billed separately alongside HCPCS Code S9379

The per diem bundling of S9379 deliberately excludes two cost categories to prevent undercoding the drug and nursing components of a home infusion episode. Getting this separation right on every claim is essential.

Drug coding with J-codes

The infusion drug itself is always reported on a separate claim line using the appropriate HCPCS J-code (or Q-code, or other drug code). The J-code identifies the specific drug, concentration, and units administered.

For example, if the infusion drug is immune globulin administered subcutaneously, the applicable J-code for the drug would appear on its own line alongside S9379. The drug line is billed per dose or per unit, depending on the J-code descriptor. Providers running mobile IV therapy operations face the same coding obligation as fixed-location infusion centers: separate drug from service code on every claim.

Nursing visit codes

Home infusion nursing visits are coded separately using the relevant home infusion nursing codes in the S-code range, or using CPT codes for skilled nursing visits depending on payer requirements. The number of nursing visits per day, the duration, and the type of service (initial training visit, routine maintenance, central line care) each affect which code applies.

Confirming who can administer IV vitamin therapy and which clinical staff qualifications satisfy the skilled nursing requirement for each payer is an important step in the billing workflow for any NOC infusion program.

Related HCPCS codes in the S9325-S9379 range

Understanding where S9379 sits within the broader HIT code range helps billing teams avoid reaching for the NOC code when a more specific option exists. The AAPC Codify HCPCS lookup lists the full S9325-S9379 range with descriptors. The most commonly used related codes are summarized below.

Code selection should always start with the drug being infused and the clinical indication, then work through the specific codes. S9379 applies only after confirming no other code fits. Defaulting to S9379 for non-hydration infusions creates audit exposure when a specific code like S9338 or S9347 should have been used.

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Documentation requirements for HCPCS Code S9379 claims

Clean S9379 claims start with complete supporting documentation. Because the code carries a NOC designation, payers apply greater scrutiny to these claims than to specific-code infusion services. Insufficient documentation is the leading cause of S9379 denials and post-payment audits.

Physician order and medical necessity

Every claim requires a signed physician order naming the infusion drug, dose, frequency, and the clinical indication justifying home administration. The order must explain why the patient cannot receive the infusion in an outpatient setting and why no specific HIT code applies. Vague orders that reference only the drug name without the clinical rationale for the NOC designation are a denial trigger.

For outpatient referrals, the CPT Code 99202 new patient office visit billing guide covers documentation standards for the initial encounter that often precedes a home infusion order, while hospital-originated referrals follow the CPT Code 99222 initial hospital inpatient billing guide standards for the home care transition.

Per diem treatment records

S9379 is billed once per calendar day of infusion service. For each billed day, the claim must be supported by a treatment record confirming service was delivered, appropriate supplies and pharmacy services were provided, and the infusion was administered or initiated that day.

If a day is billed but the patient did not receive service, the claim is incorrect. Days where service was interrupted require documentation explaining the interruption and confirming whether the per diem code should be suspended.

Care coordination notes

Because care coordination is explicitly bundled into S9379, payers may audit for documentation showing that coordination occurred. A brief care coordination note recording communication between the pharmacy, nursing agency, and prescriber for the day in question supports the claim.

Care coordination notes should be part of the standard clinical documentation workflow, not drafted in response to an audit. Practices seeking structured intake tools to support this documentation can explore Pabau’s clinical templates library for customizable intake and assessment forms.

Submitting S9379 claims: Modifier use and claim structure

Home infusion claims using S9379 are typically submitted on a CMS-1500 form (or its electronic equivalent, the 837P transaction) by the dispensing pharmacy or home infusion provider. The claim structure follows standard professional billing conventions with a few code-specific considerations.

• Units: Bill one unit of S9379 per calendar day of service. Do not bill multiple units on a single date of service to represent multiple infusions delivered on the same day.
• Modifier KX: Some commercial payers require modifier KX on S9379 to indicate that the service meets coverage criteria and that documentation supporting medical necessity is on file. Check the payer’s policy before appending modifiers.
• Modifier GY: Append modifier GY to S9379 if the service is statutorily non-covered by the payer (for example, on Medicare) and the patient has signed an advance beneficiary notice or similar waiver. GY signals a voluntary denial request.
• Modifier GZ: Append modifier GZ when the provider believes the service is likely to be denied as not medically necessary but is submitting for a formal decision. Using GZ signals the provider did not obtain an ABN or equivalent waiver.
• Diagnosis codes: Include at least one ICD-10-CM diagnosis code that directly supports the medical necessity of the infusion. The diagnosis must align with the drug being administered and the clinical rationale for home rather than outpatient delivery.

Claims management software that automates code pairing and modifier logic catches these structural errors before submission. For providers also billing ocrelizumab infusions, the HCPCS code J2350 (ocrelizumab/Ocrevus) billing guide outlines how to pair the J-code drug line with the corresponding per diem HIT code.

Pairing S9379 with the correct J-code and modifier combination is straightforward when the workflow is systematized, but error-prone when it depends on individual biller recall.

For providers exploring the full CMS HCPCS code list and coverage rules, CMS publishes free HCPCS coding and billing resources with code properties and coverage indicators, without requiring a subscription.

Conclusion

When no specific HIT code fits the infusion being provided, S9379 captures the per diem cost of administrative services, pharmacy services, care coordination, and supplies in a single daily code.

Use it only after exhausting the specific codes in the S9325–S9379 range, always code drugs and nursing visits separately, obtain prior authorization from commercial payers before the program starts, and document medical necessity for the NOC designation on every claim.

Pabau’s claims management software helps IV therapy and home infusion providers structure their per diem billing, track authorizations, and maintain the documentation trails that support clean S9379 claims. To see how it fits your practice’s workflow, book a demo with the team.

Continue your research

Running an IV therapy practice and need the right tools? IV therapy practice management covers how Pabau supports home infusion and IV drip practices with scheduling, documentation, and billing workflows.

Need to document infusion intake comprehensively before each session? IV therapy intake forms explains the clinical data points every infusion provider should capture before treatment begins.

Thinking about expanding your infusion service to mobile settings? Mobile IV therapy operations walks through the operational and compliance considerations for running infusion services outside a fixed clinical setting.

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