Training & Education

How to Mark CUI document labeling guide with security markings

Training & Education

How to Mark CUI in 2026

by Josh Manuel on Jan 28 2026
How do you properly mark Controlled Unclassified Information? This guide explains how to identify, label, and protect CUI across documents, computers, digital media, manufacturing areas, and controlled workspaces. It covers core CUI marking requirements, best practices by media type, common audit-failure mistakes, and a simple step-by-step framework for building a consistent CUI marking program aligned with NIST SP 800-171, DFARS 252.204-7012, and CMMC.