“Periodically assess the security controls in organizational systems to determine if the controls are effective in their application.” — NIST SP 800-171 Rev. 2, 3.12.1

One of the clearest signs of a mature cybersecurity program is regular self-assessment. Control 3.12.1 requires organizations to periodically assess their own security controls and determine whether those controls are working as intended.

This isn’t just an IT activity—it’s a leadership function.

And it’s one of the first places a C3PAO will look to understand if your organization treats compliance as a one-time event or as an ongoing responsibility.

What the C3PAO Is Looking For

When assessing 3.12.1, a C3PAO looks for evidence that your organization:

• Has a defined process for evaluating the effectiveness of your security controls.
• Performs those assessments on a scheduled basis (not 3 quarters-worth of assessments all in a month!)
• Reviews and documents findings, and takes action and creates POAMs on the results.
• Knows who is responsible for conducting and approving those assessments.

This control falls squarely under the OSC’s responsibility in the Shared Responsibility Matrix. While your service providers may help perform testing or gather evidence, your leadership determines:

• The frequency of reviews,
• The criteria for success, and
• How results inform risk management and improvement.

If you rely on a consultant or MSP to facilitate meetings, run scans, or prepare reports, that’s fine—but the assessment itself must belong to you. The C3PAO will expect to see that your organization reviews and accepts those results, documents follow-up actions, and integrates them into your security planning.

Otherwise, the activity looks like outsourcing, not ownership.

Why Periodic Assessment Matters

Security controls don’t last forever. Configurations drift, staff changes, and new systems introduce risk. The intent of this control is to make sure your organization is continuously validating that what you’ve built is still working.

Think of it like a health check. You wouldn’t assume you’re fine just because you had a good doctor’s visit three years ago. The same is true for your security environment.

Leaders who understand this build review cycles into their culture. They assign ownership, schedule internal reviews, and tie those results to their Plan of Action & Milestones (POA&M) process.

This is where technical and organizational maturity connect—your processes create feedback loops that lead to measurable improvement.

The Leadership Role

It’s easy to see this as a technical control, but the real question is about accountability.

Who ensures assessments actually happen?

Who verifies the results are reviewed by leadership?

Who decides when it’s time to adjust controls or invest in improvements?

Those are leadership questions, not IT tasks.

An effective process usually includes:

• A defined review cycle (quarterly, semi-annually, or annually).
• Documented results stored in a central location.
• A clear link between assessment outcomes and risk management.
• Leadership review of reports and remediation plans.

The C3PAO will likely ask to see both the assessment results and the records of leadership review—meeting minutes, sign-offs, or internal communications that prove the OSC is engaged.

Because ultimately, this control measures whether your organization understands its security posture, not whether you’ve hired someone to measure it for you.

For an affirming official, that leader in the organization who attests yearly to an SPRS score as being true, there is a great deal of personal risk under False Claims.

Shared Responsibility in Practice

Your MSP might perform vulnerability scans. Your consultant might provide compliance reviews. But those are inputs, not ownership.

Your Shared Responsibility Matrix (SRM) should show:

• The OSC is responsible for scheduling, reviewing, and approving assessments.
• Providers are responsible for conducting testing or producing data that supports those reviews.
• When your SRM accurately reflects this division, it tells the C3PAO that you know where accountability lies.

Bottom Line

Control 3.12.1 is about leadership awareness. It’s not enough to install security tools or buy compliance reports; you need to actively evaluate whether your program is working.

As a leader, your signature and your actions show that your organization owns its cybersecurity performance.

Compliance is not about passing an audit; it’s about proving that your controls are alive, tested, and continually improved.