HCPCS code S0030 – Injection, metronidazole

Key takeaways

HCPCS code S0030 describes injection of metronidazole, 500 mg, and is a deleted HCPCS Level II S-code

S codes are not recognized by Medicare Part B; S0030 was used by Medicaid and private payers only, and coverage varied by state

The current crosswalk is J1836 (Injection, metronidazole, 10 mg), or J3490 for unclassified drug claims when a payer requires it

J1836 bills per 10 mg, not per 500 mg, so a 500 mg dose is 50 units and a 1,000 mg dose is 100 units

Pabau’s claims management software helps IV therapy and infusion practices track drug billing codes, NDC numbers, and payer-specific requirements in one place

What S0030 describes: metronidazole injection 500 mg

Metronidazole is an antibiotic and antiprotozoal agent used intravenously when oral administration is not appropriate. S0030 was built for the intravenous formulation at 500 mg per dose. That dose is common in hospital outpatient settings, infusion practices, and skilled nursing facilities.

Clinicians order IV metronidazole for a defined set of clinical scenarios, including anaerobic bacterial infections and certain protozoal infections. IV therapy clinic management protocols govern how each infusion is documented.

Per FDA labeling, approved indications for metronidazole IV include anaerobic bacterial infections and surgical prophylaxis for colorectal procedures. The labeled anaerobic sites are intra-abdominal, skin and skin structure, gynecologic, bone and joint, CNS, endocarditis, and septicemia. Labeling also covers trichomoniasis, giardiasis, and amebiasis when parenteral administration is clinically indicated. Coders should not extend clinical indications beyond FDA labeling when supporting medical necessity documentation.

• Anaerobic bacterial infections: intra-abdominal, gynecologic, CNS, bone and joint
• Surgical prophylaxis: colorectal procedures requiring perioperative antibiotic coverage
• Protozoal infections: trichomoniasis, giardiasis, amebiasis when oral route is contraindicated
• Route: intravenous infusion only (the descriptor specifies injection/infusion, not oral)
• Unit: one unit of S0030 equaled one 500 mg dose; the replacement code J1836 is billed per 10 mg instead

Understanding HCPCS S codes and temporary national codes

S codes sit within HCPCS Level II but occupy a distinct policy space from J-codes and CPT codes. CMS established the S-code section as temporary national codes primarily for use by state Medicaid programs and Blue Cross Blue Shield plans. That classification has two practical consequences for billing staff. First, Medicare Part B does not recognize or reimburse S codes under any standard coverage policy. Second, Medicaid coverage varies by state, and private payer acceptance varies by contract.

J-codes, by contrast, are HCPCS Level II codes CMS maintains specifically for Medicare-covered injectable drugs and chemotherapy agents. When a drug has both an S-code and a J-code equivalent, Medicare-participating providers must use the J-code. This distinction prevents the most common billing error for codes like S0030. Submitting an S-code on a Medicare claim earns an automatic rejection. For a broader view of how these systems interact, the AAPC HCPCS code lookup provides context on Level II code sections and their payer applicability.

Is S0030 covered by Medicare or Medicaid?

Medicare Part B does not reimburse HCPCS code S0030 or any other S-code. This is a structural policy, not a code-specific coverage determination. S codes as a category are excluded from Medicare Part B fee schedule reimbursement under CMS rules. Submitting S0030 on a Medicare claim will result in automatic denial regardless of the clinical indication or documentation provided. Running an insurance eligibility verification before treatment identifies the patient’s payer type. Billing teams can then pick the correct code set before a claim goes out.

Medicaid coverage is a different question. State Medicaid programs can, and often do, recognize S codes. Coverage for S0030 varied by state while the code was active: some state programs included it in their drug reimbursement schedules, others did not. Any Medicaid program that once covered S0030 has since updated its formulary to reflect the deletion. Providers submitting to state Medicaid should use J1836 and confirm acceptance with the state’s Medicaid billing authority.

Private payers follow their own coverage determinations. Some commercial fee schedules still reference S0030 by contract. Request a contract update, and submit using J1836 with a notation about the deletion. The CMS Physician Fee Schedule lookup tool confirms which HCPCS codes carry active Medicare reimbursement rates.

Is S0030 a deleted HCPCS code? Status and history

Yes. S0030 was deleted from the HCPCS Level II code set effective June 30, 2023, and every authoritative reference source now lists it as terminated. A deleted code has been officially removed from the active HCPCS Level II code file by CMS. No payer should accept the code as a valid billing identifier after its termination date, whatever its prior coverage history.

S0030 still turns up on older payer contracts, on an explanation of benefits (EOB), and on an electronic remittance advice. The right response depends on context. On a historical claim being reviewed for appeal, the code was valid for the service date in question and may still be referenced. On a new claim being prepared today, S0030 should not be used. Providers should flag the code during charge capture review and substitute J1836 before submission.

CMS issues quarterly HCPCS updates and an annual update effective each January 1. Billing teams working with drug injection codes should subscribe to their MAC’s provider bulletin service to receive notifications when codes are added, revised, or deleted. The CMS HCPCS Level II overview page provides links to the current annual code file and quarterly update files.

S0030 crosswalk: Replacement and related codes

J1836 is the current replacement for S0030, and J3490 is the fallback when a payer demands an unclassified drug code. Choosing between them means matching the payer type and confirming the code’s status for the service date before submission.

J1836 (Injection, metronidazole, 10 mg) is the HCPCS Level II J-code that now carries IV metronidazole. It took effect on July 1, 2023, the day after S0030 was retired. Medicare Part B recognizes J-codes, and Medicaid programs and commercial payers generally accept them. That makes J1836 the appropriate crosswalk for every payer type. Verify its active status against the most recent CMS HCPCS update file before use.

The unit basis changes with the crosswalk

This is the part of the crosswalk that costs practices money. S0030 was billed per 500 mg dose, so a standard infusion was one unit. J1836 is billed per 10 mg, so the same infusion is 50 units. Carrying the old habit onto a J1836 claim underbills the drug by a factor of 50.

Two habits protect the claim. Bill the units from the milligrams documented in the infusion record, never from the number of bags hung. Then check the payer’s medically unlikely edit (MUE) for J1836, because a three-digit unit count on a drug line often trips a manual review.

When J3490 applies instead

J3490 (Injection, drug, unclassified) is an active HCPCS code CMS maintains for injectable drugs that lack a specific code. Payers using it typically require the drug name, NDC, dose, and a copy of the invoice or drug acquisition cost documentation. Reach for it only when a payer instructs you to use an unclassified code, or when J1836 is not valid for the claim’s service date. Using J3490 for a drug that has its own J-code invites denial.

Document the crosswalk and its unit basis inside the billing system itself. That one step keeps revenue cycle management teams from billing the wrong code for a service date.

Billing guidelines for metronidazole IV infusion

Whether billing under J1836, J3490, or responding to a legacy S0030 reference, the documentation requirements for metronidazole IV infusion follow the same core standards. Submitting a clean claim for an injectable drug requires specific fields that differ from standard office visit claims. Missing any of them is a leading cause of drug claim denials.

Documentation requirements

• Physician or provider order: signed order specifying drug name (metronidazole), dose (500 mg), route (IV/intravenous), frequency, and duration
• NDC number: National Drug Code for the specific product administered; required on Medicaid drug claims and by many commercial payers
• Dose administered: the units billed must match the milligrams given. One unit of J1836 is 10 mg, so a 500 mg dose is 50 units
• Diagnosis codes: ICD-10-CM codes supporting the clinical indication (e.g. anaerobic infection, specific protozoal infection) to establish medical necessity
• Place of service: office (11), on campus-outpatient hospital (22), or off campus-outpatient hospital (19). Infusion suites usually bill 11 when the practice owns them, and 19 or 22 when a hospital does. The choice affects reimbursement methodology
• Date and time of infusion: documented in the clinical record; required for infusion claims that may also bill infusion administration CPT codes

NDC reporting underpins the federal drug rebate program. State Medicaid programs therefore require it as a condition of paying a drug claim. The NDC must appear in the correct claim field with the unit-of-measure qualifier and quantity that match the product given. A premixed 100 mL bag is reported in ML, a vial in UN. Using the superbill as a structured documentation tool during the encounter helps billing staff capture NDC and dose information at point of care.

How to avoid common billing errors with S0030

Billing staff encounter five consistent error patterns with deleted codes like S0030. Each has a practical fix that reduces managing claim denials after the fact.

• Submitting a deleted code: S0030 is not active. Using it on a current claim will generate an invalid code rejection. Set up a billing system edit that flags S0030 and prompts substitution with J1836 before claim transmission.
• Carrying the old unit basis across: S0030 was billed per 500 mg, but J1836 is billed per 10 mg. A 500 mg dose is 50 units and a 1,000 mg dose is 100 units. Billing one or two units instead underpays the drug line by a factor of 50.
• Missing NDC on Medicaid claims: Medicaid requires the NDC number, unit qualifier, and quantity on all drug claims. Submitting without a complete NDC will result in denial. Build NDC capture into the infusion record at time of administration, not retrospectively.
• Failing to verify payer S-code coverage: Even when a code is active, S codes require pre-billing verification with each payer. Not all commercial plans accept S-code submissions. Verify coverage status before submitting any S-code claim, and contact the payer when the contractual language is ambiguous.
• Using J3490 when J1836 applies: J3490 is appropriate only when no specific code exists for the drug being billed. Using an unclassified code unnecessarily triggers additional documentation requirements and review scrutiny. Use J1836 as the primary code for IV metronidazole.

Systematic medical billing compliance reviews that include drug injection code audits help practices catch these patterns early. Left alone, they accumulate into a billing pattern that attracts payer audits. Reviewing remittance adjustment reason codes on denied drug claims reveals which of the above errors is occurring most frequently in a given billing cycle.

A recurring CO-4 (incorrect code) on drug injection claims is a reliable signal. It usually means a crosswalk or code status problem sits in charge capture. The guide to denial codes in medical billing explains how to read those rejections.

Reimbursement considerations for metronidazole IV

Because S0030 is a deleted code with no active fee schedule entry, no specific reimbursement rate applies to it under any current payer schedule. Reimbursement for IV metronidazole now follows J1836. For Medicare claims, payment follows the average sales price (ASP)-based rate for J1836. CMS publishes that rate in the Part B drug pricing file and the Physician Fee Schedule, and updates it quarterly. That rate is per 10 mg, so the allowed amount for a 500 mg dose is 50 times the published figure.

Medicaid reimbursement for metronidazole IV is state-determined. Most states base it on their own drug pricing methodology, typically a percentage of AWP, WAC, or ASP. Private payer rates vary by contract. Providers should not assume a prior S0030 rate carries over to J1836, since the two codes use different unit bases. Verify the fee schedule separately for each payer. The PGM Billing HCPCS lookup tool provides free access to CMS HCPCS data for confirming a code’s attributes before submission.

Infusion practices should also consider whether administration codes apply alongside the drug code. CPT codes for therapeutic drug infusion may be billed separately when metronidazole is infused rather than pushed. Code 96365 covers the initial hour of a non-chemotherapy drug infusion. The drug code and the infusion administration code together represent the complete service. Tracking both components in a structured billing workflow reduces the risk of undercoding the encounter.

How Pabau keeps drug injection codes current

In most practices the crosswalk lives in someone’s head or in a spreadsheet on a shared drive. A code is deleted in June, the replacement bills on a different unit basis, and nobody updates the charge template. The denials arrive weeks later, and the underpaid claims never surface at all.

Practice management software like Pabau puts the codes where the charge is captured. Pabau’s claims management software supports multi-line drug and administration billing. One infusion claim carries the drug code, its unit count, and the administration CPT code together. NDC and dose are recorded during the treatment note rather than reconstructed afterward.

The outcome is fewer corrected claims and fewer underbilled drug lines. Your billing team works the exceptions instead of retyping the routine ones.

Streamline drug injection billing with Pabau

Pabau’s claims management tools help infusion and IV therapy practices track drug codes, NDC numbers, and payer-specific billing requirements in one place. Billing staff spend less time correcting claims and more time on patient care.

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Conclusion

HCPCS code S0030 is a deleted temporary national code for metronidazole 500 mg injection, retired on June 30, 2023. Billing staff who meet it on an older contract or remittance should substitute J1836, the current crosswalk for every payer type. J3490 applies only when a payer explicitly requires an unclassified drug code.

The unit basis is the trap. J1836 pays per 10 mg where S0030 paid per 500 mg, so a standard 500 mg infusion is 50 units rather than one. Medicare covers no S-code at all, and Medicaid coverage still needs state-level verification of the replacement code.

Infusion and IV therapy practices run a high volume of drug injection claims. Keeping crosswalks current and tracking NDC requirements by payer carries a real administrative cost. Pabau’s medical billing software integrates charge capture, drug coding, and payer-specific requirements, so billing teams can manage billing workflows without switching between reference systems.

To see how Pabau handles drug injection billing for outpatient and infusion practices, book a demo.

Continue your research

Need to understand how billing denials happen? Denial codes in medical billing explains the most common remittance adjustment reason codes and how to respond to each one.

Managing infusion and IV therapy claims at scale? Best EMR for IV therapy reviews the features that matter most for IV therapy clinic billing and documentation workflows.

Want to reduce claim errors before submission? Submitting a clean claim outlines the documentation and coding steps that reduce first-pass denial rates for drug injection claims.

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