CMMCDocs.comOne of the most significant investments defense contractors make on the path to CMMC Level 2 is migrating to a FedRAMP-authorized cloud environment. For most organizations in the DIB, this means Microsoft 365 GCC High — but understanding why it is needed and what it actually provides is essential before signing a contract.
Why Commercial Cloud Is Not Enough
Standard commercial cloud services like Microsoft 365 Business, Google Workspace, or AWS commercial regions are not designed to meet the data residency, personnel screening, and access control requirements for CUI. NIST SP 800-171 requires that CUI be processed and stored in environments with specific protections that commercial cloud providers do not guarantee in their standard offerings.
DFARS 252.204-7012 explicitly requires that cloud service providers meet FedRAMP Moderate baseline (or equivalent) requirements when processing, storing, or transmitting CUI. This is not optional — it is a contractual obligation.
Understanding FedRAMP
The Federal Risk and Authorization Management Program (FedRAMP) is a government-wide program that provides a standardized approach to security assessment, authorization, and continuous monitoring for cloud products and services. FedRAMP authorization comes at three impact levels: Low, Moderate, and High.
For CMMC purposes, you need a cloud environment that is FedRAMP Moderate authorized at minimum. FedRAMP High provides additional protections and is required for some sensitive workloads.
GCC High vs GCC vs Commercial
Microsoft 365 Commercial: Standard offering for businesses. Not FedRAMP authorized. Not suitable for CUI.
Microsoft 365 GCC (Government Community Cloud): FedRAMP High authorized but designed primarily for government agencies. It meets many requirements but has some limitations for DIB contractors handling CUI under DFARS.
Microsoft 365 GCC High: Specifically designed for defense contractors and organizations handling CUI under DFARS and ITAR. FedRAMP High authorized with additional DoD-specific controls. Data is stored in sovereign US data centers operated by screened US persons. This is the standard recommendation for DIB contractors needing CMMC Level 2.
Shared Responsibility
A critical concept that many contractors misunderstand is the shared responsibility model. Moving to GCC High does not automatically make you CMMC compliant. The cloud provider is responsible for the security of the cloud infrastructure. You are responsible for the security of your configuration, your data, your user accounts, and your policies within that environment.
You must still configure conditional access policies, enable and enforce MFA, set up data loss prevention rules, manage user access reviews, configure audit logging, and implement all the other controls that operate at the tenant level. GCC High gives you a compliant foundation — you must build a compliant operation on top of it.
Cost Considerations
GCC High licensing costs are significantly higher than commercial Microsoft 365 — often 2-3x per user per month. Factor in migration costs, training, potential custom development for integrations that do not work in GCC High, and ongoing administration. For small contractors, this can be a significant budget line item, but it is a necessary investment for CUI compliance.