Common CMMC Mistakes: Incomplete CRM Documentation

Top 15 Most Common CMMC Mistakes, #15: Incomplete CRM Documentation

This article is part of our expert-led series: The Top 15 Most Common CMMC Compliance Mistakes (and How to Solve Them). Over the next 16 days, we’ll break down the most frequent mistakes, misunderstandings, and misconceptions we see companies make on their journey to CMMC certification, based on insights from seasoned CCPs, CISOs, and CCAs.

Today’s focus: the critical importance of detailed Customer Responsibility Matrix (CRM) documentation and how incomplete ownership mapping can stall your assessment.

What You’ll Learn

• The role of the CRM in CMMC
• What auditors expect from CRM documentation
• How to build a CRM that aligns with your SSP and SRM
• Common mistakes and how to avoid them

The Importance of Documentation

In CMMC, documentation is proof of implementation. Your Customer Responsibility Matrix (CRM) is a central piece of evidence, especially when using External Service Providers (ESPs). Too often, organizations provide high-level or vague CRMs that don’t clearly delineate which security requirements are handled internally and which are delegated to providers.

The CRM isn’t just paperwork, it’s the map that helps the auditor understand the distribution of responsibilities across the OSC and its vendors. And unless your CRM explicitly aligns to the Shared Responsibility Matrix (SRM) and the objectives in your System Security Plan (SSP), it’s likely to raise questions, slow down the audit, or result in findings.

What the CRM Should Include

A detailed CRM should:

• Align with your SSP and POA&M
  It must reference the same systems, boundaries, and responsibilities as outlined elsewhere in your documentation.
  
  
• Be mapped to each CMMC objective
  At CMMC Level 2, there are 110 requirements and 320 assessment objectives (per NIST SP 800-171A). For any outsourced control, your CRM should show who owns each objective and how it’s implemented and verified.
  
  
• Include ESPs and Subservice Entities
  Don’t forget cloud providers, MSSPs, IaaS/SaaS platforms, and even sub-contracted third parties that influence your environment.
  
  
• Demonstrate evidence of agreement
  This includes signed SRMs, contracts, or attestation letters showing that the ESP agrees to and is accountable for the assigned responsibilities.
  
  

What Auditors Expect

CCAs and CCPs performing your CMMC assessment are looking for:

• Traceability: Can they follow responsibility for each practice from documentation to implementation?
  
  
• Clarity: Is it clear which party (OSC or ESP) owns each control and objective?
  
  
• Evidence: Can the ESP produce documentation or attestation showing ownership and implementation?
  
  

Poor CRM documentation is a red flag for assessors. It signals incomplete risk understanding, poor vendor oversight, and potential non-compliance.

Expert Tip: Build CRM Into Vendor Selection

When selecting ESPs, MSPs, or SaaS tools that may impact your CUI environment, build CRM alignment into your procurement process. If the vendor cannot provide documentation showing how they meet NIST 800-171 controls (or at least validate your ownership of gaps), they may not be appropriate for your compliance boundary.

You may also request a FedRAMP Moderate or equivalent certification as a baseline, or map the vendor’s attestation (e.g., SOC 2 Type II) to specific CMMC controls.

Compare: CRM vs. SRM

In Summary: Getting Your CRM Documentation Correct

Don’t treat your CRM as an afterthought. It’s one of the most scrutinized documents during CMMC assessment, especially if you rely on third parties for critical functions like hosting, backups, or identity management. Building and maintaining a detailed, objective-level CRM aligned to your SSP and SRM not only reduces audit friction but demonstrates maturity in your compliance governance.

Key Takeaways

• CRM documentation must clearly show who owns which objectives.
  
  
• Auditors expect alignment between the CRM, SSP, and evidence.
  
  
• Shared responsibilities with ESPs should be formalized and auditable.
  
  
• Lack of CRM clarity often results in findings, delays, or failed assessments.
  
  

Up Next In Our Top 15 Most Common CMMC Mistakes Series:

In our next installment, we’ll look at the most common legal documentation mistake in CMMC compliance: failing to get agreement and objective-level accountability from your ESPs.