If you’re a defense contractor preparing for CMMC and you’ve started calling vendors, you’ve probably noticed something confusing: three completely different types of companies all claim they “do CMMC.” A compliance consultant. A C3PAO. A managed service provider (MSP). They sound interchangeable. They are not. Hiring them in the wrong order is one of the most expensive mistakes contractors make in the months before an assessment and it’s avoidable once you understand what each one is actually allowed to do.
This is the plain-English breakdown.
You almost always need a CMMC consultant (specifically, a Registered Practitioner) first. They scope your environment and prepare you for certification. A C3PAO comes last; they perform the official assessment that grants your certification. An MSP may run pieces of your IT infrastructure, but they cannot certify you or, on their own, prepare you for a CMMC assessment. Most contractors who fail or stall did it by getting this sequence wrong.
Now the details.
A CMMC consultant typically a Registered Practitioner (RP) working independently or through a Registered Provider Organization (RPO) is the vendor who gets your environment ready before certification. Their role is advisory and hands-on preparation. An RP can:
Critical limitation: An RP cannot certify you. They prepare; they don’t assess. That distinction is enforced by the CMMC ecosystem to keep the assessor side independent.
When you need one: From day one. Before you buy a single security tool, change a single configuration, or call a C3PAO. Every dollar you spend without a scoped environment is a dollar at risk of being wasted.
A C3PAO (Certified Third-Party Assessment Organization) is the authorized body that conducts your official Level 2 assessment. They evaluate whether your environment meets all 110 controls, score the assessment, and report the result that determines whether you receive certification. By design, they are independent; they cannot help you remediate, build your SSP, or fix gaps they find. Their entire value is impartial evaluation.
Critical points contractors miss:
When you need one: Last. After your RP has prepared the environment, validated the SSP, collected evidence, and confirmed you’re audit-ready. Calling a C3PAO before you’re prepared is how contractors burn six months of waiting only to fail the assessment.
A managed service provider (MSP) runs IT services on your behalf networks, endpoints, email, sometimes cloud infrastructure. Some MSPs market themselves as “CMMC-ready” or “CMMC-compliant.” Read that language carefully. There’s no such thing as a “CMMC-certified MSP” issuing certifications to its clients. What an MSP can legitimately offer is a hosting environment or service that’s been built to support CMMC requirements (for example, a GCC High Microsoft 365 deployment).
That’s useful but it’s not certification, and it’s not preparation.
Critical points:
When you need one: After scoping. If your RP determines you need a GCC High enclave, an MSP with that capability becomes part of the solution. Hiring an MSP first before scoping risks paying for infrastructure you didn’t need.
# | Vendor | What they do | When to engage |
1 | CMMC Consultant (RP) | Scope, gap-assess, plan, prepare | Day one |
2 | MSP / cloud provider (if needed) | Provide compliant hosting infrastructure | After scoping confirms it’s required |
3 | C3PAO | Conduct official certification assessment | Only when fully audit-ready |
Doing it in any other order causes one of three predictable problems. Hiring an MSP first means paying for infrastructure built around the wrong scope. Calling a C3PAO first means waiting six months for an assessment you fail because nobody prepared you. Skipping the RP entirely usually means a System Security Plan that doesn’t match your real environment and the single most common reason assessments fail.
For an RP/RPO, the question that separates good from bad is simple: Can you fix what you find? A consultant who hands you a gap report and walks away has done about 20% of the actual work. The other 80% network segmentation, access control, encryption, documentation, training is engineering. An RP backed by an in-house engineering team can execute remediation. One without will hand you the report and a phone number for someone else, doubling your timeline and your cost.
For a C3PAO, look for current authorization on the CyberAB Marketplace, realistic scheduling (anyone promising a near-term slot probably has a problem), and clear scoping of the assessment itself.
For an MSP, verify that the specific service supports CMMC (most general MSPs do not), that they hold appropriate certifications themselves, and that they’re transparent about which controls they handle vs. which remain your responsibility.
Rudram Engineering is built around the gap most contractors discover too late: the RP who can also fix what they find. We’re a systems engineering firm with 18+ years in the Defense Industrial Base, an in-house Registered Practitioner, and the engineering team to execute remediation under one roof. Same team scopes your environment, identifies your gaps, builds your SSP, and implements the technical controls straight through to C3PAO readiness. One team. One timeline. One accountable partner.
Both, but in order. A consultant (RP) prepares you. A C3PAO certifies you. You cannot skip the preparation step.
No. C3PAOs are independent assessors. They evaluate; they cannot prepare, advise, or fix gaps in the same engagement.
No. An MSP can provide compliant hosting infrastructure, but you still need an RP to scope your environment and a C3PAO to certify you.
An RP is trained and credentialed in the CMMC ecosystem to advise on certification preparation scoping, gap assessment, SSP development, and remediation guidance against the 110 NIST SP 800-171 controls.
No. Ecosystem rules require separation between preparation and assessment to maintain assessor independence.
Rudram Engineering, Inc. | Rockledge, FL | Serving the Defense Industrial Base for 18+ years | Trusted by NASA, the U.S. Air Force Academy, and Raytheon
