Controlled Unclassified Information: Labeling Requirements for CMMC and NIST 800-171

As the Department of Defense’s (DoD) Cybersecurity Maturity Model Certification (CMMC) framework begins rolling out and working its way into DoD contracts, one of the most common questions we get are: “What is Controlled Unclassified Information (CUI)” and “How do you label CUI appropriately?”

In the Federal Government’s own words: “CUI is information the government creates or possesses, or that an entity creates or possesses for or on behalf of the government, that a law, regulation, or government-wide policy requires or permits an agency to handle using safeguarding or dissemination controls.” The other part of information being considered CUI is that it is not meant for public release without proper authorization, but does not warrant a Confidential, Secret, or Top Secret classification from the Federal Government.

CUI is further broken into 24 categories and 83 subcategories. Each subcategory then provides a designation as either CUI Basic or CUI Specified. These categories and subcategories can be found here: Information that is designated as CUI Specified contains specific marking, handling, and dissemination requirements that must be followed. But what about CUI Basic?

CUI Basic has a general handling, dissemination, and marking requirement that must be applied to every record containing information which is considered CUI Basic. To start, all records must have a header that reads: “CUI”. This header cannot contain anything else. Then on the first page or cover page of every CUI containing record, the following information must be annotated:

  • Line 1: the name of the DoD Component (not required if identified in the letterhead)
  • Line 2: identification of the office creating the document
  • Line 3: identification of the categories contained in the document
  • Line 4: applicable distribution statement or limited dissemination control (LDC)
  • Line 5: name and phone number or email of POC

This marking requirement applies to every CUI containing record, whether that is a document, presentation, email, or any other type of record designated as containing CUI. Both NIST 800-171 and CMMC, have a control that directly requires these markings.

In NIST 800-171, this is Control 3.8.4 and in CMMC, this is Practice MP.3.122 which reads:

“Mark media with necessary CUI markings and distribution limitations.”

There are two simple questions to determine if information is CUI:

  1. Does the information meet the standards for classification? If yes, it is not CUI, it is classified information.
  2. Does the information fall within a law, regulation, or government-wide policy? If no, then it cannot be considered CUI.

If the information is considered CUI, the next steps are to determine which category and subcategory of CUI the information falls into. If the subcategory is CUI Specified, follow the listed marking requirements. If it is CUI Basic, apply the required header and annotation listed above.

CMMC and NIST 800-171 both require a policy and procedures document for meeting the labeling requirements for CUI, and individuals handling CUI must be trained on how to label CUI appropriately. This training is provided by the DoD, who also provide a CUI Marking Job Aid with this training that lists out the specific CUI marking requirements. This Job Aid can be found through the link below.

If you would like to learn more about CUI, the purpose of establishing the CUI designation, or CUI marking requirements, the DoD’s CUI training is the best place to start:

How Can Schneider Downs Help?

Schneider Downs currently offers CMMC readiness and consulting services as a Registered Provider Organization (RPO). Our team includes a Certified CMMC Provisional Assessor, and several other members currently in process of applying for CMMC Certified Assessor status who plan on completing training in Q2 of 2021. OSCs should note that a single firm cannot perform both consulting and audit services for a single client per the CMMC-AB standards. In the meantime, until such requirements are made public, we can help your organization prepare for CMMC by performing an assessment against the NIST 800-171 framework. For more information visit or contact us to get started. 

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