How to Choose the Right C3PAO for Your CMMC Assessment

Key Vetting Questions for DoD Contracts

In the complex landscape of Department of Defense (DoD) contracting, Cybersecurity Maturity Model Certification (CMMC) Level 2 isn’t just another compliance checkbox – it’s a critical gateway to securing our nation’s defense supply chain. For Defense Industrial Base (DIB) companies, navigating this journey means partnering with a CMMC Third-Party Assessment Organization (C3PAO). Choosing the right C3PAO can mean the difference between a smooth, successful CMMC assessment and a costly, reputation-damaging failure. You must ensure you’re making an informed decision that truly secures your future DoD contracts.

Do I Need All 110 NIST SP 800-171 Controls for CMMC Level 2?

One of the most dangerous misconceptions circulating in the CMMC ecosystem is the idea that you can achieve Level 2 certification by only implementing a subset of controls. You might encounter C3PAOs marketing that you “only have to complete X controls” to pass.

This is fundamentally misleading and dangerous advice.

DoD Fact: CMMC Level 2 is directly mapped to the 110 practices of NIST SP 800-171. Every single one of these 110 practices, along with their associated 320 assessment objectives, must be implemented and demonstrated for a successful Level 2 assessment.

Matt Travis, CEO of the Cyber-AB (CMMC Accreditation Body), has consistently emphasized this point. He and the Cyber-AB are unequivocally clear that all 110 NIST SP 800-171 controls are required for CMMC Level 2 certification. Any C3PAO suggesting otherwise is not only providing bad guidance but could be leading your organization toward a failed assessment, wasted resources, and potential future DoD audits that expose your non-compliance.

“If you don’t do all 110 controls, then you haven’t been certified for CMMC Level 2.”

— Matt Travis, Cyber-AB CEO (paraphrased from various public statements and webinars)

Understanding POA&M and Conditional Certification

A high-quality C3PAO will clearly explain the conditional certification path. While you cannot be missing any of the 110 controls entirely, the CMMC program allows for a Plan of Action and Milestones (POA&M) for minor deficiencies—specifically, a limited number of practices designated by the DoD.

However, the practices listed in the Cyber-AB’s “excluded” or “critical” list (often involving requirements like the SSP or key configuration controls) must be MET at the time of the assessment. If a C3PAO cannot clearly articulate which practices are allowable on a POA&M and the strict 180-day remediation window, they may not possess the required regulatory depth.

What Are the Essential Questions to Ask a Potential C3PAO?

Just because an organization is listed as an authorized C3PAO doesn’t automatically mean they are the right C3PAO for your company. It’s essential to look beyond basic certification and delve into their actual expertise.

The Intake/Quote Process

For small and medium-sized businesses (SMBs), the intake phase is a major key to vetting an assessor. As the National Defense ISAC (ND-ISAC) notes, a good C3PAO will show their familiarity and flexibility through their initial questions.

Scrutiny of Scope

Does the C3PAO ask detailed questions about your CUI scope and boundaries before providing a quote? If they accept you immediately with minimal scoping effort, they may be setting both your organizations up for a costly mid-assessment disconnect.

Avoiding Extremes

While you should seek an assessor who provides a reasonable assessment, you should also avoid assessors who draw unreasonable lines during vetting or those who are at the “bottom of the barrel” in terms of pricing and quality, as their results may be nullified.

Technical Acumen and Environment Experience

A good C3PAO goes beyond simply checking boxes. Their assessors should possess deep technical knowledge to truly understand how your controls are implemented and why they meet the CMMC requirements.

Defining vs. Implementing

The assessment is not just a policy review. A C3PAO must confirm the security practice is active and repeatable.

“We’re looking for the two pieces to control: are you defining it, and are you implementing it? The implementation piece is just as big of a deal as the policy piece.”

— John Sciandra, Lead CCA, KLC Consulting

Service Providers (MSPs/CSPs)

Since most SMBs rely on external service providers, the assessor must have proven experience. Ask a C4PAO: Have you assessed environments with my specific Managed Service Provider (MSP) or Cloud Service Provider (CSP)? Do you require proof of business need before assessing a service provider?

Specialized Assets

Ask a C3PAO: about their experience assessing common DIB environments, such as development labs, legacy software, or Operational Technology (OT) systems that require compensating controls.

Mastery of the EIT Assessment Methodology

Ask your potential C3PAO: to detail how they execute the Examine, Interview, Test (EIT) methodology for your specific controls, demonstrating their commitment to the rigor of the CMMC Assessment Process (CAP).

“We’ve had an assessment where the OSC actually had a screenshot for every objective level… you are kind of guided very quickly to work your way through what the OSC is trying to present to you. It goes a lot to not only preparation but presentation of the artifacts.” 

— John Sciandra, Lead CCA, KLC Consulting

Clarity and Defensibility of the Final Assessment Report

The C3PAO’s most important deliverable is the official Assessment Report (AR), which documents every finding. A key failure point is often in the simple details:

Configuration Control

A professional C3PAO will probe documentation consistency, especially in configuration management.

“Version numbers—that’s a big one. You’ll see a version number on the SSP that doesn’t match the version number on the network diagram. That falls under configuration management, and those architectural changes that haven’t been caught up in the SSP and network diagrams are common issues.” 

— John Sciandra, Lead CCA, KLC Consulting

Evidence Sufficiency

Be aware that certain controls allow for subjective judgment. Ask the C3PAO: When looking for evidence of compliance, what do you believe is sufficient? One example or more than one example? Does it depend on the control?

Report Quality

A quality C3PAO ensures this report clearly and precisely articulates why a control was marked “Not Met” with reference to the specific NIST SP 800-171A assessment objectives that were not met.

The Cost of Choosing the Cheapest C3PAO

The implications of choosing the wrong C3PAO extend far beyond a failed initial assessment:

• Cost vs. Quality: Cost is not everything! Choosing the cheapest assessor may, in the long run, be more expensive if the small business finds itself having to be re-assessed due to a flawed initial audit.
• Wasted Investment: Time, money, and resources spent on an assessment that doesn’t hold up are irretrievable.
• Failed DoD Audit: The DoD retains the right to conduct its own audits. If your CMMC certification is found to be based on an inadequate assessment, you could face severe consequences, including contract termination or debarment.
• Insecure Systems: Most importantly, a superficial assessment leaves your critical data vulnerable, undermining the very purpose of CMMC.

Making the Right Choice

As a C3PAO ourselves, we understand the intricacies and the gravity of the CMMC Level 2 assessment. Our commitment is to provide thorough, technically sound, and transparent assessments that give DIB companies true confidence in their cybersecurity posture and their CMMC certification.

When evaluating C3PAOs, ask the hard questions:

• How do you ensure our assessment is reasonable and that you fully understand our unique SMB environment?
• How do you handle scope definition and ensure all 110 controls are addressed, and which are excluded from POA&M?
• Can you walk us through how your team applies the Examine, Interview, Test (EIT) methodology to a key security domain in a hybrid IT environment?
• What is your experience assessing environments that utilize my specific  Managed Service Provider (MSP)?

Don’t compromise on your CMMC quest to become compliant. Choose a C3PAO that offers genuine expertise, integrity, and a commitment to helping you achieve robust cybersecurity and lasting compliance.