CMMC Assessment Checklist
If you think you are ready for a CMMC assessment, use this resource to test where you actually are before contacting a professional.
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The four top mistakes of organizations seeking CMMC certification
By now, we have assessed enough organizations seeking certification (OSCs) to see patterns. We see patterns of common successes, but we also have seen trends in mistakes. The following are four of the most common mistakes we encounter as a CMMC Third-Party Assessor Organization (C3PAO).
1. Selecting the Wrong C3PAO
Choosing a Certified Third-Party Assessor Organization (C3PAO) is not like hiring a typical IT auditor. It is a strategic partnership that can determine your contract eligibility for the next three years. Choosing the wrong C3PAO can result in people problems, process problems, and technology problems. An OSC must carefully vet the C3PAO they choose.
There are three key factors to consider when selecting a C3PAO:
- Does the Price Seem Too Good to be True?: Some firms will offer flat formulas, GRC tools, or a variety of “low cost” options that could actually result in a poor assessment experience. If a C3PAO says they figure your quote by multiplying the number of employees you have by a certain number, you probably should dig deeper.
- Beware the Conflict of Interest Trap: You cannot hire the same firm for both consulting (remediation) and your official assessment. Choosing a C3PAO that blurs these lines can invalidate your certification. We talk more about this conflict of interest in our post titled Why a CMMC Assessor Cannot Offer Consultation Services to the Same Company.
- The Strategy: Verify their credentials on the Cyber AB Marketplace. Ask about their experience with your specific industry (e.g., manufacturing vs. software dev) and their "re-assessment" policy if you hit a snag.
2. Failing to Control the Scope
There are three areas to consider when building your assessment scope:
- Identify asset types
- Determine whether anything that will not store, process, or transmit Controlled Unclassified Information (CUI) can be separated or segregated from the facets of the company that do touch CUI.
- Determine whether you will work with an ESP (External Services Provider). If you are, creating a RACI (Responsible Accountable Consulted Informed) chart is a great way to make sure nothing slips through the cracks.
Companies that decide to include everything in the assessment run the risk of spending money and time beyond what is necessary.
3. Lack of Assessment Planning
Although the C3PAO decides if OSCs achieve certification, it is up to the OSC to determine the narrative the C3PAO will be judging against. The organization should have the capability to answer the following questions before a C3PAO enters the building:
- What: What type of CUI do you have, in what format does it exist, what kinds of assets do you have?
- Who/Why: Why are you receiving CUI, who can access it, and who presides over access?
- Where: Where does the CUI reside? Are you enclaved? Where is CUI stored? Are you working with a CSP (Cloud Service Provider), an MSP (Managed Services Provider), or an MSSP (Managed Security Services Provider)?
- How: How do employees access CUI? How do you protect CUI external to the organization?
4. Documentation Mismatch with Data Systems
In 2026, assessors are beginning to move past simple "policy reviews" and are performing deep-dive technical validations. A "Not Met" finding is almost inevitable if your System Security Plan (SSP) does not match reality.
It is essential to meet all 110 controls in NIST SP 800-171r2, but it is equally essential to meet all 360 objectives in NIST SP 800-172a. Moreover, your SSP should map to what your documentation and environment show. Documentation is often the mistake that stops an assessment from moving forward.
Need Some Help Preparing for CMMC?
Choosing a C3PAO and preparing for a third-party CMMC assessment may seem intimidating. There are professional consultants who can guide you through the preparation phase. You can use a C3PAO for this so long as they do not assess you. You can also search in the CyberAB marketplace for RPOs (Registered Provider Organizations).
If you feel ready for your third-party assessment, please contact us today and let us kick off the process with you.