3PAO vs. C3PAO: Understanding the Difference

Word count: ~920 Specificity markers hit: (4) Common mistake — hiring a 3PAO instead of a C3PAO; (5) Decision point — which type you need based on what you're certifying; (2) Cost/time estimate — C3PAO assessment timelines and typical fees

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Two acronyms, one letter apart, completely different purposes. If you're a defense contractor trying to get CMMC (Cybersecurity Maturity Model Certification) certified, the distinction matters — because hiring the wrong type of assessor wastes time and money.

Here's the plain-language version.

What a 3PAO Is

A 3PAO — Third-Party Assessment Organization — is an independent assessor accredited by the American Association for Laboratory Accreditation (A2LA) to conduct FedRAMP (Federal Risk and Authorization Management Program) assessments. FedRAMP is the federal government's authorization framework for cloud services. If a company wants to offer a cloud product to federal agencies, they need FedRAMP authorization. The 3PAO is who does the independent assessment to get there.

3PAOs test cloud service providers. Their customers are companies like software vendors and managed service providers building federal-facing cloud offerings. They are not in the business of assessing defense contractors for CMMC — even though some of them would like to be.

What a C3PAO Is

A C3PAO — Certified Third-Party Assessor Organization — is accredited by the Cyber AB (the CMMC Accreditation Body, formerly known as the CMMC-AB) to conduct CMMC assessments for defense contractors. If your company touches Controlled Unclassified Information (CUI — sensitive but unclassified government data) and needs CMMC Level 2 or Level 3 certification, a C3PAO is the only organization authorized to certify you.

C3PAOs have to meet specific requirements: they must be authorized by the Cyber AB, their assessors must hold Certified CMMC Assessor (CCA) or Certified CMMC Professional (CCP) credentials, and the lead assessor for a Level 2 assessment must be a CCA with Level 2 scope. This isn't just paperwork — the authorization structure is designed to ensure assessors actually understand the NIST SP 800-171 controls your environment needs to meet.

The Overlap That Creates Confusion

Some organizations hold both accreditations. A company might be a 3PAO (authorized to do FedRAMP assessments) and a C3PAO (authorized to do CMMC assessments) at the same time. That's fine — they're separate accreditations, and there's no rule against holding both.

The confusion arises when a defense contractor sees "government cybersecurity assessments" in a firm's marketing and assumes they're qualified for CMMC. Always verify Cyber AB accreditation specifically. You can look up C3PAOs on the Cyber AB marketplace at cyberab.org. If an assessment firm isn't listed there, they cannot issue a CMMC certificate — period.

The Common Mistake

Defense contractors sometimes hire a 3PAO thinking it qualifies for CMMC. It doesn't. A 3PAO assessment against FedRAMP security controls produces a FedRAMP assessment report. That report has nothing to do with CMMC certification. CMMC requires an assessment against the CMMC Level 2 or Level 3 practices by an authorized C3PAO, conducted according to the CMMC Assessment Process (CAP) guide.

This mistake usually happens because: - The contractor found a firm through a DoD vendor database that lists security assessment services - The firm described itself as "government cybersecurity experts" without clarifying which framework - Someone on the team confused "federally-related assessment" with "CMMC assessment"

The fix is simple: before signing any assessment contract, confirm the firm's Cyber AB C3PAO status and ask to see the names of the Certified CMMC Assessors who will conduct your assessment.

Which One You Need

If you're a defense contractor pursuing CMMC Level 1: You don't need either. Level 1 is self-assessed annually and submitted to the Supplier Performance Risk System (SPRS). No third-party assessor required.

If you're a defense contractor pursuing CMMC Level 2 certification: You need a C3PAO. This is a third-party assessment and the most common path for contractors handling CUI under a DoD contract with a CMMC Level 2 requirement.

If you're a cloud service provider seeking FedRAMP authorization: You need a 3PAO.

If you're doing both (a defense contractor who also provides cloud services to the government): You may need both, but for separate purposes. The CMMC assessment covers your internal environment for handling CUI. The FedRAMP assessment covers your cloud service offering for agency customers.

What to Expect from a C3PAO Assessment

A CMMC Level 2 assessment covers all 110 practices in NIST SP 800-171 across 14 control domains. The C3PAO will examine your documentation (primarily your System Security Plan, or SSP), interview your personnel, and test your technical controls. Assessments typically take two to four weeks from kickoff to report delivery, depending on the size and complexity of your environment.

Cost varies significantly by organization size and readiness. Small companies with a well-prepared SSP and tight CUI environment can expect $30,000–$75,000 for the assessment itself. Mid-size contractors with more systems and personnel to interview typically pay $75,000–$150,000. These figures are assessment fees only — remediation work before the assessment is separate.

Once the C3PAO submits their findings to the Cyber AB and the results are validated, CMMC certificates are issued by the Cyber AB, not the C3PAO. The C3PAO conducts the assessment. The Cyber AB issues the certification.

The Bottom Line

If you're a defense contractor: you want a C3PAO. Look them up on the Cyber AB marketplace, verify your lead assessor has a CCA credential, and ask for a scope meeting before signing anything. The assessment process is defined — what changes between firms is pricing, scheduling, and how well they communicate with contractors who are new to the process.

If a firm pitches you on CMMC compliance work and you can't find them in the Cyber AB marketplace, walk away.

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Ready to go deeper? Read our Tier 2 guide on what to expect from the CMMC assessment process — including how C3PAOs evaluate each control and what "Not Met" means for your certification timeline.