21 C.F.R. § 207.33 : Food and Drugs — FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES — DRUGS: GENERAL — REQUIREMENTS FOR FOREIGN AND DOMESTIC ESTABLISHMENT REGISTRATION AND LISTING FOR HUMAN DRUGS, INCLUDING DRUGS THAT ARE REGULATED UNDER A BIOLOGICS LICENSE APPLICATION, AND ANIMAL DRUGS, AND THE NATIONAL DRUG CODE — NATIONAL DRUG CODE — What is the National Drug Code (NDC), how is it assigned, and what are its requirements?

(a) What is the NDC for a drug and what products must have unique NDCs? The NDC for a drug is a numeric code. Each finished drug product or unfinished drug subject to the listing requirements of this part must have a unique NDC to identify its labeler, product, and package size and type.
(b) What is the format of an NDC?
(1) Except as described in paragraph (b)(4) of this section, the NDC must consist of 10 or 11 digits, divided into three segments as follows:
(i) The first segment of the NDC is the labeler code and consists of 4, 5, or 6 digits. The labeler code is assigned by FDA.
(ii) The second segment of the NDC is the product code and consists of 3 or 4 digits, as specified in paragraphs (b)(2) and (3) of this section.
(iii) The third segment of the NDC is the package code and consists of 1 or 2 digits as specified in paragraphs (b)(2) and (3) of this section. The package code identifies the package size and type of the drug and differentiates between different quantitative and qualitative attributes of the product packaging.
(2) The following combinations of labeler code, product code and package code character lengths are permissible:
(i) If a labeler code is either 5 or 6 digits in length, it may be combined with:
(A) A product code consisting of 4 digits and a package code consisting of 1 digit for a total NDC length of 10 or 11 digits (5-4-1 or 6-4-1), or
(B) A product code consisting of 3 digits and a package code consisting of 2 digits for a total NDC length of 10 or 11 digits (5-3-2 or 6-3-2).
(ii) If a labeler code is 4 digits in length, it may be combined only with a product code consisting of 4 digits and a package code consisting of 2 digits for a total NDC length of 10 digits (4-4-2).
(3) A registrant or private label distributor with a given labeler code must use only one Product-Package Code configuration (e.g., a 3-digit product code combined with a 2-digit package code or a 4-digit product code combined with a 1-digit package code). This single configuration must be used in all NDCs that include the given labeler code that are reserved in accordance with § 207.33(d)(3) or listed in accordance with § 207.49 or § 207.53.
(4) An alternatively formatted NDC that is approved for use by the relevant Center Director may be used for the following HCT/Ps if they are minimally manipulated: Hematopoietic stem/progenitor cells derived from peripheral and cord blood, and lymphocytes collected from peripheral blood.
(c) Who must obtain an NDC labeler code and how is the code assigned and updated?
(1) Each person who engages in manufacturing, repacking, relabeling, or private label distribution of a drug subject to listing under this part must apply for an NDC labeler code, by providing the following information:
(i) The name, physical address, email address, and other contact information FDA may request, of the person for whom the NDC labeler code is requested;
(ii) The type(s) of activities (e.g., manufacture or repacking) in which the person requesting the NDC labeler code engages with respect to human drugs; and
(iii) The type(s) of drug(s) (human, animal, or both, and prescription, nonprescription, or both) to which the NDC labeler code will be applied.
(2) Each person who is assigned an NDC labeler code must update the information submitted under paragraph (c)(1)of this section within 30 calendar days after any change to that information.
(d) How is an NDC proposed for assignment by FDA, when is an NDC assigned by FDA, and how can a proposed NDC be reserved?
(1) An NDC is proposed for assignment by FDA when it is submitted for the first time with listing information in accordance with § 207.49 or § 207.53, as applicable.
(i) Each manufacturer, repacker, or relabeler must propose for assignment by FDA an NDC that includes its own labeler code for each package size and type of drug that it manufactures, repacks, or relabels for commercial distribution.
(ii) In addition, if a drug is distributed under the trade name or label of a private label distributor, the manufacturer, repacker, or relabeler must also propose for assignment by FDA an NDC that includes the labeler code of the private label distributor under whose trade name or label the drug is distributed, for each package size and type so distributed.
(2) If a proposed NDC conforms to the requirements of this section and is not reserved for a different drug or was not previously assigned to a different drug, FDA will assign the NDC to a drug when it receives listing information required for that drug under § 207.49 or § 207.53.
(3) A manufacturer, repacker, relabeler, or private label distributor may voluntarily reserve a proposed NDC for a drug, before the drug is listed, by submitting the following information:
(i) A proposed NDC that conforms to the requirements of this section;
(ii) The established name of the active ingredient(s) and the strength of each active ingredient in the drug; and
(iii) In the case of a finished drug product, the dosage form, and route of administration.
(4) If the required information is submitted and the proposed NDC is properly formatted and not already assigned or reserved, FDA will reserve the proposed NDC for a period of 2 years from the date of submission. If the drug for which the proposed NDC is reserved is not listed in accordance with § 207.49 or § 207.53 during such 2-year period, the reservation of the proposed NDC will lapse. FDA may also cancel the reservation of a proposed NDC at any time on the request of the person whose labeler code is included in the proposed NDC.
(e) How must the information be submitted to us? The information described in paragraphs (c) and (d) of this section must be submitted electronically unless FDA grants a waiver under § 207.65.

21 C.F.R. §207.33