As the Department of Defense (DoD) phases in the Cybersecurity Maturity Model Certification (CMMC), third-party certification is now required for organizations working within the Defense Industrial Base (DIB). By 2025, all DoD contractors will need to be CMMC certified, and the only way to achieve that is through an assessment conducted by a Certified Third-Party Assessment Organization (C3PAO).
This guide covers everything you need to know about C3PAOs—from what they do, how they’re accredited, and how to prepare for a CMMC assessment.
What Is a CMMC C3PAO?
A CMMC C3PAO is an organization authorized by the Cyber AB (formerly the CMMC Accreditation Body) to perform official CMMC assessments. These entities evaluate whether contractors meet the necessary CMMC requirements for handling Controlled Unclassified Information (CUI) or Federal Contract Information (FCI).
Prior to CMMC, DoD contractors self-attested compliance with NIST SP 800-171. However, the DoD recognized that self-certification lacked consistency and accountability, leading to the development of CMMC—a model requiring third-party certification to enforce robust cybersecurity across the defense supply chain.
A Quick Primer on CMMC
The CMMC establishes security standards across three levels of maturity:
- Level 1 – Foundational: Basic safeguarding of FCI
- Level 2 – Advanced: Full alignment with NIST SP 800-171 controls
- Level 3 – Expert: Enhanced controls against Advanced Persistent Threats (APTs), based on NIST SP 800-172
Only C3PAOs can conduct the assessments required to grant Level 2 or 3 certification. As of 2025, organizations handling CUI will be required to obtain Level 2 certification through an assessment by a C3PAO.
Do You Need CMMC Certification?
If your organization has a contract with the DoD or handles FCI/CUI, you will need CMMC certification. Level 1 may be self-assessed in some cases, but Level 2 and above must be validated by a C3PAO.
Not sure which level you need? Consider:
- Are you a prime or subcontractor on a DoD contract?
- Do you process or store CUI?
If the answer is yes to either, a CMMC assessment—and a qualified C3PAO—will be required.
Responsibilities of a C3PAO
A C3PAO is responsible for:
- Conducting formal CMMC assessments
- Evaluating implementation of required security controls
- Ensuring impartiality and consistency during audits
- Issuing certification decisions based on findings
C3PAOs CAN NOT provide consulting services for the organizations they assess.
How Does a Business Become a C3PAO?
To be approved as a C3PAO, an organization must:
- Register with the Cyber AB
- Pass a CMMC Level 2 (or Level 3) Assessment
- Undergo a background check and personnel vetting
- Comply with ISO/IEC 17020 standards
- Use secure FedRAMP-compliant cloud storage (if storing assessment data)
- Establish a quality management system and dispute resolution process
U.S.-based organizations are eligible to apply, and foreign entities may be considered in the future if their countries enter into mutual agreements with the DoD.
Accreditation Timeline and Costs
The path to becoming a C3PAO includes:
- $1,000 application fee
- $200 activation fee upon acceptance
- CMMC assessment costs (vary by provider and scope)
- ISO 17020 accreditation (27-month grace period to comply)
These investments reflect the need for impartial, high-quality assessments that protect national security.
Finding and Hiring a C3PAO
The Cyber AB maintains an official CMMC Marketplace, where organizations can search for:
- Certified C3PAOs
- Registered Provider Organizations (RPOs)
- CMMC-trained assessors
While prices and scopes vary, assessment costs depend on:
- Maturity level required (Level 2 or 3)
- Size and complexity of the organization
- The assessor’s experience
To ensure clarity and efficiency, engagements should include a clear scope of work and timeline.
Building on this foundation, RSI Security is proud to be a Certified Third-Party Assessment Organization (C3PAO), authorized to conduct official CMMC Level 2 assessments. As a result, organizations across the Defense Industrial Base trust RSI Security to help them meet evolving DoD security requirements.
Preparing for a CMMC Assessment
Before hiring a C3PAO, it’s critical to prepare. Since C3PAOs cannot offer guidance during the official assessment, many organizations work with an RPO to get audit-ready.
- Gap Analysis: Identify areas of non-compliance
- Implementation Planning: Install and institutionalize necessary controls
- Continuous Monitoring: Stay agile to evolving threats and compliance requirements
Quick-Start Guide
| Question | Answer |
| Does My Business Need CMMC? | If you work with the DoD or handle CUI/FCI, yes. |
| Who Grants Certification? | Only a certified C3PAO can issue CMMC Level 2+ certification. |
| Who Certifies C3PAOs? | The Cyber AB authorizes all C3PAOs. |
| Can My Business Become a C3PAO? | Yes, if U.S.-based, ISO 17020 compliant, and Level 2+ CMMC certified. |
How RSI Security Can Help
RSI Security is a C3PAO authorized by the Cyber AB to perform official CMMC Level 2 assessments. We work directly with organizations across the Defense Industrial Base to evaluate and certify compliance with the CMMC framework.
If you’re preparing for your CMMC certification, RSI Security provides trusted, impartial assessments to help you meet the latest DoD cybersecurity standards. Stay ahead of the 2025 CMMC rollout. Contact RSI Security today to schedule your formal assessment with an authorized C3PAO.
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