7 CMMC Assessment Mistakes Small Businesses Keep Repeating

No one enjoys finding out they’ve missed the mark, especially after months of prep. For small businesses aiming to work with the Department of Defense, following the Cybersecurity Maturity Model Certification (CMMC) isn’t just a checkbox—it’s a gatekeeper. But too often, companies fall into the same avoidable traps that delay or derail their CMMC assessment.

Treating CMMC Compliance as a Last-Minute Checklist Item

Far too many small contractors treat CMMC compliance like a final exam they can cram for. The issue? CMMC compliance requirements aren’t a “do it the night before” task. By the time a c3pao shows up for a CMMC assessment, every policy, practice, and control should already be well-documented and fully operational. Waiting until the last moment doesn’t leave room to address gaps, let alone fix them.

Instead of scrambling, organizations should start their readiness efforts early. The process involves more than paperwork—it’s a culture shift that takes time. Especially with CMMC level 1 requirements and CMMC level 2 requirements, the security measures must be part of day-to-day operations, not rushed into place just before a deadline.

Neglecting the Importance of Continuous Security Monitoring

Some companies think once they check off their controls, they can coast. That’s not how it works. Continuous monitoring is a core expectation, particularly under CMMC level 2 requirements, where advanced threats must be detected and mitigated regularly. A set-it-and-forget-it mindset can leave systems exposed between audits.

Good security doesn’t sleep. Alerts, log reviews, and incident response should be active and routine. Businesses that treat monitoring as a living process—not a one-time task—are the ones that avoid surprises during a CMMC assessment. Skipping it creates blind spots that a c3pao will quickly uncover.

Undervaluing Documented Security Practices

Saying “we do it” isn’t the same as proving it. Small businesses often assume that verbal confirmation or causal processes are enough. But under CMMC compliance requirements, documented proof is everything. Policies, procedures, system security plans—these need to be written, maintained, and actually followed.

Without documentation, even the best security practices don’t count. A c3pao can’t assess what’s not on paper. Businesses need to treat their documentation as an ongoing part of operations, not a postscript. Good records show maturity, and maturity is the whole point of the CMMC model.

Overlooking Employee Cybersecurity Awareness Training

Firewalls and encryption help—but untrained people are often the biggest vulnerability. Some businesses skip over user training because it feels low-tech or too simple to matter. That’s a mistake. Phishing, weak passwords, and accidental data leaks are all preventable with consistent employee training, and it’s a core part of CMMC level 1 requirements.

Staff should understand their role in keeping data secure. That includes everyone, not just IT. A short annual slide deck isn’t enough. Real security awareness means monthly reminders, mock phishing tests, and open discussion around threats. If the team isn’t prepared, the controls won’t work.

Misinterpreting Scope Boundaries Within Compliance Requirements

Failing to define system boundaries accurately is one of the sneakier mistakes. Businesses might over-scope by including systems that don’t handle controlled unclassified information (CUI), or under-scope by missing out on tools and vendors that do. This confusion around scope throws off everything from risk assessments to technical controls.

Clear scoping affects how CMMC level 2 requirements are implemented. A company must understand what’s in and what’s out—cloud providers, remote access systems, mobile devices—all of it. If the wrong assets are left out or unnecessary ones are pulled in, the CMMC assessment becomes much harder to pass.

Overconfidence in Existing Security Infrastructure

Just because a business has firewalls and antivirus software doesn’t mean they’re CMMC-ready. Many companies believe their current IT setup automatically meets the requirements, especially if they’ve passed other audits. But CMMC is its own beast. It emphasizes maturity, evidence, and control implementation across specific domains.

Being secure is one thing. Being compliant is another. What passes for best practices elsewhere might not meet CMMC’s structured expectations. Businesses that assume they’re “already good” often find themselves caught off-guard when they dive into the actual CMMC compliance requirements and see how deep the checklist goes.

Underestimating Timeframes Required for Evidence Preparation

Collecting screenshots, logs, training records, and system plans takes time. Small businesses often realize this too late. They may think pulling evidence together is a quick weekend task—until they realize some controls require 90 days or more of demonstrated performance.

A rushed timeline leads to missed proof, incomplete packages, or policies that aren’t backed up by action. Preparing for a CMMC assessment isn’t just about answering yes or no—it’s about showing how and when. Businesses that start early, keep records up to date, and plan months ahead are in the best position when it’s time to engage with a c3pao.