s the Cybersecurity Maturity Model Certification (CMMC) reshapes the defense industrial base, prime contractors are facing a difficult reality: many of their long-standing, trusted subcontractors are not ready to meet new cybersecurity requirements. While CMMC flowdown is intended to strengthen supply chain security, it is also introducing operational, financial, and strategic challenges, especially when primes want to continue working with preferred subs who are struggling to meet compliance needs.

The tension between mission continuity and regulatory enforcement is the heart of the issue. Prime contractors rely heavily on established subcontractors for specialized capabilities, institutional knowledge, and proven performance. However, under CMMC, those relationships are now contingent on demonstrable cybersecurity maturity. If a subcontractor cannot meet the required CMMC level, the prime may be forced to reconsider the relationship regardless of past performance.

One of the biggest challenges primes face is limited visibility into subcontractor readiness. Many subcontractors, particularly small and mid-sized businesses, are still in the early stages of understanding CMMC requirements. Some may still be completely unaware of requirements. Common deficiencies include lacking a complete System Security Plan (SSP), having significant gaps in National Institute of Standards and Technology (NIST) security guidelines for protecting Controlled Unclassified Information (CUI) in non-federal information systems (typically known as NIST SP 800-171 controls), or being unprepared for third-party assessments. Primes often discover these pitfalls late in the process when timelines are tight and options are limited.

While awareness has improved, it is still common, especially among smaller firms, for subcontractors to be effectively “CMMC-unaware.” To mitigate this, primes should be asking targeted, practical questions early in the relationship:

• What is your current Supplier Performance Risk System (SPRS) score?
• What is your CMMC scope (enclave vs. enterprise)?
• How do you send and receive CUI?
• What is your Plan of Action and Milestones (POA&M) closeout timeline?

An inability to answer these questions clearly is often a strong indicator that the subcontractor is unlikely to meet compliance timelines.

Compounding this issue is the cost and complexity of compliance. For subcontractors handling CUI, achieving CMMC Level 2 requires significant investment in technology, personnel, and process maturity. Third-party assessments add additional cost on top of implementation. Smaller firms often struggle to justify these expenses, particularly when Department of War work is only a portion of their business. This creates a difficult decision for primes: invest in helping a trusted partner reach compliance or replace them with a vendor who is already compliant—often introducing new risk in performance or cost.

In response, some primes attempt to reduce compliance burden through scoping strategies. By carefully segmenting systems and limiting the flow of CUI, they may be able to keep certain subcontractors at CMMC Level 1 rather than Level 2. However, this requires a deep understanding of data flows, something many organizations struggle with. In many cases, subcontractors still require access to technical data that qualifies as CUI, making higher-level compliance unavoidable.

To manage these pressures, primes are increasingly taking a more active role in supporting their supply chain. This includes providing guidance, sharing templates, and even offering financial or technical assistance to help subcontractors meet requirements. Some are formalizing this approach through supplier development programs, while others are addressing it by conducting cybersecurity assessments during the proposal phase. Early engagement allows primes to identify risks sooner and gives subcontractors more time to prepare.

A common pitfall is selecting a provider that attempts to shoehorn both the prime and its subcontractors into a rigid, one-size-fits-all model. These solutions often prioritize standardization over flexibility, requiring organizations to abandon existing tools, workflows, or collaboration methods. For primes working with a network of preferred subcontractors, this can be highly disruptive.

This becomes especially problematic when subcontractors are already struggling with compliance. Forcing them into an unfamiliar environment might slow adoption or even push them out of the supply chain entirely. Instead of lowering the barrier to compliance, it raises it.

Primes should instead prioritize solutions that integrate with existing workflows. This means evaluating whether a provider can:

• Support current engineering and collaboration processes
• Operate within hybrid environments (cloud, on-premises, or mixed)
• Allow phased adoption rather than requiring full migration
• Scale across subcontractors with varying levels of maturity

Flexibility is key when managing a diverse supplier base. Not all subcontractors will be at the same stage of readiness, and a rigid solution can create unnecessary friction across the ecosystem.

Equally important is data flow alignment. A strong CMMC solution should enable precise control over where CUI resides and how it moves without imposing artificial constraints that disrupt program execution. Overly restrictive environments can hinder productivity, while poorly designed ones can introduce compliance gaps.

Ultimately, primes need to treat CMMC as an extension of their operational model, not a replacement for it. The most effective providers will focus on adapting security controls to the business, rather than forcing the business to adapt to the tool.

CMMC is driving a fundamental shift in the defense industrial base. Cybersecurity is now a core requirement for participation, not a secondary consideration. Primes that successfully navigate these challenges, support their subcontractors, select flexible solutions, and align compliance with real-world workflows will be best positioned to maintain their supply chains and compete effectively in this new environment.