On a drug claim line, the NDC is reported as the qualifier N4 followed by the 11-digit NDC with no hyphens, then a unit-of-measure qualifier (F2, GR, ME, ML or UN) and the quantity of that NDC product used. The HCPCS code and its units are reported on the same line.
Why claims carry the NDC
The HCPCS code says which drug and dose were billed; the NDC says which product was used. State Medicaid programs require NDCs on physician-administered drugs so they can collect manufacturer rebates, and many Medicare Advantage and commercial payers require them too.
The format
The NDC segment of a line has four parts: the qualifier N4, the 11-digit NDC with no spaces or hyphens, a unit-of-measure qualifier, and the quantity. For example: N400006302602 ML8.
On a paper CMS-1500 it goes in the shaded upper part of item 24 for the drug's service line. In the 837P electronic claim it goes in the drug identification segment of the line (loop 2410): the NDC in LIN03, and the unit qualifier and quantity in CTP05 and CTP04. Institutional claims carry the same information on the drug line with the revenue code and HCPCS code.
Unit-of-measure qualifiers
| Qualifier | Meaning | Typical use |
|---|---|---|
| ML | Milliliter | Liquids: solutions and suspensions measured by volume |
| UN | Unit (each) | Countable items: vials, tablets, kits, prefilled syringes |
| GR | Gram | Powders, creams and ointments measured by weight |
| ME | Milligram | Products measured in milligrams |
| F2 | International unit | Products dosed in international units |
Pick the qualifier that matches how the product's package is measured, not how the dose is expressed. Payers publish their own preferences, particularly for powders that are reconstituted before use.
A worked example
A patient receives 200 mg of pembrolizumab from 100 mg/4 mL single-dose vials, package NDC 0006-3026-02. The HCPCS code is J9271 (Injection, pembrolizumab, 1 mg), so the HCPCS units are 200.
The 11-digit NDC is 00006-3026-02. The dose used two vials, 8 mL in total, so the NDC quantity is ML 8. The line carries J9271 × 200 units and N400006302602 ML8.
The HCPCS units and the NDC quantity measure different things and are rarely the same number. Both have to be right.
Questions
Can one claim line have more than one NDC?
Yes, when one HCPCS code was supplied from more than one product (for example two vial sizes). Payers handle this differently: some want repeated lines with the same HCPCS code, one per NDC. Check the payer's instructions.
How many decimal places can the NDC quantity have?
The 837 transaction allows fractional quantities (commonly up to three decimal places). Payers may round, so report the actual amount used.