National drug code

[5][3] The following NDC structure rules apply depending on the length of certain segments.

The official FDA format for NDCs separates the 3 segments with dashes.

This is the format in which the NDC must be submitted by labelers since mandatory electronic listing was established in June 2009.

The Centers for Medicare and Medicaid Services (CMS) had created an 11-digit NDC derivative, which pads the labeler, product, or package code segments of the NDC with leading zeroes wherever they are needed to result in a fixed length 5-4-2 configuration (but always written without dashes).

[8] This format was adopted by data standards selected pursuant to HIPAA regulation, thus other government agencies' lists and databases (such as the UMLS) may contain the 11-digit derivative of the original NDC.

In some applications, the fully expanded 5+4 digit labeler+product code is used as a 9-digit number to identify a product regardless of packaging.