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N815 Remark Code: NDC Unit Count Missing or Invalid

N815 means the claim line for a drug had a National Drug Code (NDC) but the NDC unit count, the quantity of the product given measured in NDC terms, was missing, incomplete, or invalid. The payer needs it to price the drug and check it against the billed HCPCS units.

Quick facts

Code
N815 (RARC N815)
Status
Active In use since July 1, 2019.
Code set
Remittance Advice Remark Codes (RARC)
Group codes
  • CO (Contractual Obligation): The drug line was denied for a data error the provider can correct. It isn't billable to the patient.
Official description
Missing/Incomplete/Invalid NDC Unit Count
X12 Remittance Advice Remark Codes, retrieved September 25, 2026
Last verified
against the official X12 list.

What N815 means

Drug lines on medical claims usually carry two quantities. The HCPCS units in box 24G describe the drug in the terms of the HCPCS Level II code, such as per 10 mg. The NDC quantity describes how much of the actual product was used, measured in the NDC’s own unit (milliliters, grams, international units, or units/each). N815 applies to the second one: the NDC quantity was blank, incomplete, or not acceptable.

Payers, especially Medicaid programs that collect drug rebates, use the NDC quantity to price the drug and verify that it matches the HCPCS units billed. N815 typically appears with CARC 16.

Common causes

  • Quantity left blank because only the NDC number was entered.
  • HCPCS units copied into the NDC quantity without converting to the product’s measure.
  • Formatting errors, such as extra decimals, commas, or leading text.
  • Quantity inconsistent with the unit of measure, for example a milliliter volume reported with the unit qualifier for each.

How to fix it

  1. Confirm the dose given in the administration record and the product (NDC) used.
  2. Calculate the NDC quantity in the unit of measure that matches the package, for example the total milliliters drawn from a vial.
  3. Enter it in the NDC supplemental data, with the correct unit qualifier, and double-check the HCPCS units in box 24G still match the dose.
  4. Submit a corrected claim with resubmission code 7 in box 22.

How to prevent it

  • Store each NDC with its unit of measure and a conversion to HCPCS units in your drug master file.
  • Make the NDC quantity a required field whenever an NDC is entered.
  • Run drug claims through Claims Validator to catch missing or mismatched NDC quantities before submission.

Codes that may appear with N815

  • CO-16 (Claim/service lacks information or has submission/billing error(s).): The claim lacks information needed for adjudication; N815 names the NDC quantity.
  • N816 (Missing/Incomplete/Invalid NDC Unit of Measure): The NDC unit of measure, which tells the payer what the quantity is counted in.
  • M119 (Missing/incomplete/invalid/ deactivated/withdrawn National Drug Code (NDC).): The NDC itself is missing, invalid, or deactivated.
  • N846 (National Drug Code (NDC) supplied does not correspond to the HCPCs/CPT billed.): The NDC doesn't correspond to the HCPCS code billed.

N815 FAQ

Are NDC units the same as HCPCS units?

No. HCPCS units follow the code's descriptor, such as a set number of milligrams. NDC units describe the quantity of the actual product dispensed, in milliliters, grams, international units, or each. The two numbers are often different.

What does an invalid unit count look like?

Common examples are a zero or blank quantity, a quantity with too many decimal places, or a quantity that is impossible for the product and unit of measure reported.

Where is the NDC quantity on a CMS-1500?

In the shaded supplemental area above the service line in box 24, together with the N4 qualifier, the 11-digit NDC, the unit of measure qualifier, and the quantity, following the payer's formatting rules.