The one-line difference
FedRAMP authorizes a cloud service (the platform — AWS GovCloud, Microsoft 365 GCC High, Azure Government) for use by federal agencies. CMMC certifies a defense contractor (your organization) to handle Controlled Unclassified Information under DFARS 252.204-7021. A FedRAMP-authorized cloud is an input to your CMMC assessment, not a substitute for it.
Control baselines side by side
- FedRAMP Moderate — 323 controls from NIST SP 800-53 Rev. 5. Required baseline for cloud services handling CUI.
- FedRAMP High — 410 controls. For cloud services handling sensitive federal data with high impact.
- CMMC Level 2 — 110 controls from NIST SP 800-171 Rev. 2, 320 assessment objectives from NIST SP 800-171A. Required baseline for contractors handling CUI.
- NIST 800-171 is a curated subset of 800-53 Moderate — that's the structural overlap that makes inheritance possible.
What you can actually inherit
When you process CUI inside a FedRAMP Moderate (or higher) cloud, the cloud carries some of the underlying control implementation. The cloud provider's Shared Responsibility Matrix lists which controls the platform fully owns, which are shared, and which remain entirely yours.
Common pattern in GCC High: physical security, environmental controls, parts of audit and accountability, and most of system and communications protection are inherited. Identity, configuration management, incident response, and personnel security stay almost entirely on the contractor. A C3PAO will want to see your SRM in writing — assumed inheritance is not inheritance.
Common mistakes
- "We use GCC High so we're CMMC compliant." No — GCC High closes ~20 of 320 objectives on its own. The contractor still owns the other 300.
- Pursuing FedRAMP when CMMC Level 2 is the actual requirement. FedRAMP is for cloud service providers, not contractors. If you're not selling a SaaS to the government, you don't need a FedRAMP ATO.
- Mixing FedRAMP Low with CUI. Low does not meet the FedRAMP-equivalent baseline DFARS 7012 requires for CUI handling. Moderate is the floor.
- Ignoring the FedRAMP-equivalent path. Cloud services that are FedRAMP Moderate equivalent (not formally authorized) can meet 7012 if they pass a third-party assessment using the FedRAMP body of evidence — DoD memo CIO M-21-09 covers the criteria.
How Athena handles the boundary
Athena ingests your cloud provider's SRM, maps each line to NIST 800-171A objectives, and pre-fills the inherited columns of your SSP. What's left becomes your real readiness backlog. The evidence collection guide shows what each remaining objective needs.