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A Shared Responsibility Matrix is a formal document used by Department of Defense (DoD) contractors to define which internal teams or external service providers are responsible for implementing, managing, and evidencing each of the 110 security requirements in NIST Special Publication 800-171. These requirements form the foundation for Cybersecurity Maturity Model Certification (CMMC) Level 2.
Most defense contractors rely on external service providers such as cloud vendors or managed security partners for core technology and cybersecurity operations. Without clearly assigning who is responsible for each control, gaps in implementation or evidence often go unnoticed until an assessment is underway.
To address this, the matrix uses the RACI model, which stands for:
| Responsible – Performs the task | |
| Accountable – Owns the outcome | |
| Consulted – Provides subject matter expertise | |
| Informed – Needs to be updated on progress or changes |
This matrix is not a standalone tool. It integrates with your System Security Plan (SSP) and supports your readiness for a CMMC assessment. It helps eliminate assumptions, clarifies roles, and ensures full coverage of responsibilities across internal teams and providers. This is especially important when handling Controlled Unclassified Information (CUI).
Why SRMs Are Critical for CMMC Level 2 Compliance
CMMC Level 2 requires full and documented implementation of all 110 NIST SP 800-171 controls. However, many contractors assume that service providers are covering certain controls without verifying or documenting the responsibility. That assumption can lead to costly findings during an assessment.
Without a Shared Responsibility Matrix:
| Responsibility for controls is often misunderstood | |
| Important controls may not be implemented or properly evidenced | |
| Gaps can emerge during an assessment, delaying certification or requiring remediation |
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This matrix removes ambiguity. It provides clarity to assessors and internal teams alike. Each control is matched with the right party, and the supporting documentation is easy to locate. Beyond assessment readiness, it demonstrates operational maturity and a proactive approach to security governance.
What Does a Shared Responsibility Matrix Include?
An effective matrix is more than a spreadsheet. It provides a detailed view of how responsibilities are assigned and supported across your compliance environment.
Key components include:
Control-by-control mapping using the RACI model:
| Responsible – Who implements the control | |
| Accountable – Who ensures the control meets its intent | |
| Consulted – Who provides input and expertise | |
| Informed – Who is notified of changes or results |
References to supporting documentation, such as:
| Policies and procedures |
|
| Technical configurations and screenshots | |
| Logging systems or security tools | |
| Third-party service agreements or attestations |
Integration with compliance documentation:
| SSP | |
| Plan of Action and Milestones (POA&M) | |
| Vendor contracts or SLAs |
When completed correctly, the matrix provides confidence that all parties involved understand their responsibilities and can demonstrate evidence during a CMMC assessment.
Who Needs a Shared Responsibility Matrix?
Any DoD contractor or subcontractor that handles Controlled Unclassified Information and uses external vendors for IT, cloud services, or cybersecurity should have this matrix in place.
Examples include:
| Organizations using AWS GovCloud or Microsoft Azure Government | |
| Contractors using managed security services, such as MDR or SOC-as-a-Service | |
| Businesses relying on third parties to operate, host, or monitor sensitive systems |
This matrix is especially critical when:
| You have multiple vendors supporting various aspects of your environment | |
| Internal and external teams both contribute to control implementation | |
| Assessment readiness requires clearly documented accountability |
How to Create and Maintain a Shared Responsibility Matrix
Building a matrix is a structured process that starts with clarity and collaboration. You don’t need specialized software. What you need is accurate documentation, knowledge of your environment, and coordination with your service providers.
Steps to build your Matrix:
| Start with all 110 NIST SP 800-171 controls | |
| Use the RACI model to define roles for each control | |
| Link each assignment to evidence and implementation detail | |
| Review and validate with internal stakeholders and external vendors | |
| Integrate it into your SSP and other compliance documentation |
Keep it up to date by reviewing it when:
| You onboard a new vendor | |
| You change internal ownership or responsibilities | |
| Your system architecture or boundaries shift | |
| You prepare for an upcoming CMMC assessment |
The matrix should reflect how your environment operates today. Treat it as a living document that evolves with your business.
How MAD Security Helps Build Compliant SRMs
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MAD Security works with DoD contractors, subcontractors, and suppliers to ensure compliance documentation meets and exceeds assessment expectations. That includes developing and maintaining Shared Responsibility Matrices that are accurate, complete, and aligned with your operations.
Our team helps you:
| Map each control in NIST SP 800-171 using the RACI model | |
| Clarify roles between your internal teams and external providers | |
| Link real-world implementation and evidence to each control | |
| Embed the matrix into your compliance management framework | |
| Keep it current through our Virtual Compliance Management platform |
We have supported contractors and Certified Third-Party Assessor Organizations preparing for assessments. Our clients rely on us to bring order and clarity to complex security environments, and we deliver with precision.
Final Thoughts: Clarity Is Compliance
Assumptions create risks. When no one takes ownership of a control, that control is often left incomplete. A Shared Responsibility Matrix fixes that.
By clearly defining who is doing what, you reduce confusion, increase accountability, and prepare your organization for a successful CMMC assessment. The matrix shows your assessors and your internal teams that responsibilities are defined, roles are understood, and controls are implemented and supported.
If you are working toward CMMC Level 2, a Shared Responsibility Matrix, it is not optional. It is foundational for a mature, secure, and compliant operation.
Frequently Asked Questions (FAQs)
Original Publish Date: TO BE FINALIZED
By: MAD Security
