UB04 Code-Code Field/Qualifiers Code RX: National Drug Code (NDC)

Overview

The qualifier RX in UB‑04 Field 81 (Code‑Code Field) identifies that the accompanying value is a Prescription code. According to the NUBC UB‑04 Field 81 definitions, “RX = Prescription” NUBC List.

When to Use

Typical scenarios include:

• Inpatient or outpatient drug administration where the NDC is required for reimbursement or tracking.
• Claims for pharmacy services or infusion therapy where the drug’s NDC must be reported alongside other procedure codes.
• When the payer mandates NDC reporting on the UB‑04 for prescription drugs, especially for Medicare Part B or Medicaid claims.

If no NDC is applicable (e.g., non‑prescription supplies), a different qualifier (such as HCP for HCPCS codes) should be used. The MassHealth guide emphasizes using only the code sets listed in the NUBC for qualifier fields ^[1].

Step‑by‑Step Claim Example

A hospital administers an intravenous antibiotic to a patient. The drug has an NDC 0002-1234-01. On the paper UB‑04:

1. In Field 81 (Code‑Code Field), enter the qualifier RX in the first two characters.
2. Immediately after the qualifier, enter the NDC (with the appropriate 11‑digit format, e.g., 00002123401).
   • Field 81 entry: RX00002123401
3. The corresponding Field 43 (Drug Administration) or other drug‑related field may be completed separately per payer requirements, but the NDC link is established by Field 81.
4. Ensure the prescription drug is also coded in Field 44 (HCPCS/Rate Code) or Field 46 (Revenue Code) as needed.

Note: The MassHealth UB‑04 guide does not provide a specific example using RX, but the qualifier must be used exactly as defined by the NUBC. For electronic submissions, the same data would be sent in the equivalent electronic loop.

Common Mistakes & Audit Red Flags

• Using the wrong qualifier: Selecting RX for non‑prescription drugs or supplies may trigger denials or requests for correction. Use HCP for HCPCS codes or CPT for CPT codes when appropriate.
• Omitting the check digit: NDCs reported on the UB‑04 often require the full 11‑digit format, including the check digit. A missing or incorrect digit can cause claim rejection.
• Placing the qualifier in the wrong field: The qualifier RX is valid only in Field 81. Do not put it in Field 80 (Remarks) or Field 43.
• Inconsistent NDC format: Some payers require a specific NDC format (e.g., 5‑4‑2, 4‑4‑2, or 11 digits). Always follow the payer’s specifications.
• Missing NDC for injected drugs: Certain payers, including MassHealth, may require NDC reporting for all injectable drugs administered in a facility. Failure to report can lead to recoupment. The MassHealth billing guide reminds providers to follow the payer’s medical policies ^[1].

Related Codes/Fields

Field / Qualifier	Description	Usage
Field 81 RX	Prescription (NDC) qualifier	Indicates the subsequent code is an NDC
Field 81 HCP	HCPCS code qualifier NUBC List	Used when reporting HCPCS procedure codes
Field 81 CPT	CPT Category II code qualifier NUBC List	Used for performance measurement codes
Field 81 ZZ	Provider Taxonomy (generic qualifier) NUBC List	Applied when no more specific qualifier exists
Field 43	Drug Administration	Often used together with RX to report drug details
Field 44	HCPCS/Rate Code	Contains the procedure code for the drug administration
Field 46	Revenue Code	Identifies the revenue center (e.g., 0256 for drugs)

Note: All qualifiers listed in the NUBC Field 81 definitions are drawn from “Code Sets for the UB‑04 Claim Form” NUBC List. The MassHealth guide references the same UB‑04 form instructions ^[1]. ---END---

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References

[1] MassHealth UB‑04 Guide — https://www.mass.gov/doc/ub-04-billing-guide-0/download