Your Guide to DoD IL4/IL5 Authorization: Requirements, Readiness, and Common Pitfalls Explained

As the Department of Defense (DoD) continues to accelerate its Zero Trust strategy, organizations supporting national security missions face increasing expectations for how they secure, monitor, and manage sensitive information.  

For cloud service providers (CSPs), defense contractors, and system integrators handling Controlled Unclassified Information (CUI) or National Security Systems (NSS) data, obtaining DoD Impact Level 4 (IL4) or Impact Level 5 (IL5) authorization has become a critical milestone and significant competitive differentiator. 

The path to authorization can be complex, but understanding what to expect and how to prepare can lead to a smoother, more achievable IL4/IL5 authorization journey. In this article, we outline what organizations need to know about the IL4/IL5 landscape and proven strategies to accelerate readiness, streamline assessments, and maintain compliance. 

Understanding DoD IL4 and IL5  

The DoD Cloud Computing Security Requirements Guide (SRG) establishes a tiered framework for securing DoD workloads, with IL4 and IL5 representing two of the most stringent levels. Both levels extend beyond traditional cloud security expectations: 

What is DoD Impact Level 4? 

IL4 applies to mission-critical systems supporting DoD operations and supports CUI that requires stronger protection than what is provided in FedRAMP. IL4 authorization requires adherence to NIST SP 800-53 controls, with DoD-specific overlays.  

What is DoD Impact Level 5? 

IL5 supports higher-sensitivity CUI and NSS data, requiring stricter access controls, expanded monitoring, and enhanced isolation, such as physical and logical separation of DoD-only tenants.  

Why DoD IL4/IL5 Authorization Matters Now More Than Ever 

The DoD’s shift toward a Zero Trust architecture combined with rising cyber threats has led to increased expectations for how defense-focused systems are validated. As a result, IL4/IL5 has become a foundational requirement for operating in today’s defense ecosystem. Organizations that establish strong governance now will be better positioned for faster onboarding of new DoD workloads and meeting emerging DoD and federal compliance requirements. 

When is DoD IL4/IL5 Required with Respect to FedRAMP 

The Defense Information Systems Agency (DISA) authorization process recognized FedRAMP Moderate authorizations and grants reciprocity at the Impact Level 2 (IL2) for existing FedRAMP Moderate authorizations. All CSOs seeking IL4 or IL5 will require a 3PAO assessment on the additional controls and parameters for IL4/5 to be submitted to DISA. 

Key Milestones in the DoD SRG Authorization Process 

The authorization process involves a series of structured steps, broadly requiring the following:

1. Sponsorship and Scoping

Before your assessment can begin, a DoD mission owner or component sponsor must support the effort. This step also involves scoping your assessment and determining whether IL4 or IL5 is appropriate based on data classifications and mission needs. 

2. Selecting an Authorization Path

Organizations must identify their path through Provisional Authorization (PA), FedRAMP Moderate/High + DoD add-ons, and component-level authorizations. The authorization path impacts required documentation, assessment rigor, and timelines.

3. Documentation Development

Documentation development includes: 

1. System Security Plan (SSP) 
2. Policies and procedures 
3. Architecture diagrams
4. Continuous Monitoring Strategy
5. POA&M documentation 

4. Third Party Assessment of the CSO

The third party assessment organization (3PAO) serves as an independent and accredited assessor of the CSO. The rigorous assessment includes: 

1. Control validation 
2. Evidence-based assessment 
3. Technical and architectural deep dives 
4. Interviews and demonstrations 

DISA security assessments place heavy emphasis on boundary clarity, logging, monitoring, and role-based access enforcement. DISA serves as a validator of the 3PAO assessment results and as an overall authorization entity for the CSO. 

5. Authorization Decision and Continuous Monitoring

After addressing findings and completing required remediation, the sponsoring authority or DoD CIO issues an authorization, though the work doesn’t stop there. Continuous monitoring is required to maintain authorization and ensure controls remain effective over time. An annual assessment by an accredited 3PAO will be required as part of continuous monitoring obligations. 

How to Prepare for Your DISA Assessment 

Organizations that successfully achieve IL4/IL5 tend to have strong readiness programs with: 

1. Clear Governance and Shared Responsibility Models:  
   Boundary decisions must be explicit with a clear understanding of what you manage, what customers manage, and what is inherited from your underlying infrastructure. 
   
   
2. Evidence-Backed Control Implementations: 
   Assessors expect logs, config files, screenshots, test results, and automation outputs that show ongoing control enforcement. 
   
   
3. Alignment With DoD Overlays:  
   NIST SP 800-53 controls alone are not enough. DoD overlays bring additional audit requirements, such as strengthened authentication, enhanced isolation, and expanded event logging and retention. 
   
   
4. Network and System Isolation:  
   For IL5 especially, isolation is non-negotiable. Boundary definitions, segmentation, and access restrictions must be fully defensible. 

Key Considerations for Achieving and Maintaining DoD IL4/IL5 Compliance 

Achieving authorization is only the first hurdle. Maintaining compliance requires continuous verification that the system remains in its authorized state. 

The Importance of Continuous Monitoring 

DISA and DoD components increasingly expect demonstrable, near-real-time evidence that: 

1. Configurations remain consistent 
2. Critical files have not been altered 
3. Unauthorized changes trigger alerts 
4. System drift is detected and remediated quickly 

Integrity Monitoring and Change Control   

Solutions like file integrity monitoring (FIM), system integrity assurance, and controlled baselines are essential to: 

1. Enforce least privilege 
2. Detect anomalous behavior 
3. Support Zero Trust architecture principles 

These practices directly support continuous authorization expectations and often help organizations avoid compliance drift, which is a common cause of surprise findings during reauthorization cycles. 

Common Pitfalls to Avoid 

Across assessments, several repeatable issues can emerge: 

1. Unclear or overly broad system boundaries 
2. Incomplete or inconsistent SSPs and diagrams 
3. Underestimating DoD overlay requirements 
4. Insufficient logging or monitoring maturity 
5. Gaps in vulnerability and patch management cadence 
6. Belief that inherited controls eliminate the need for evidence 
7. Lack of a repeatable change-control process 

Most of these issues can be addressed early through readiness activities and effective architectural planning. 

Strategic Steps to Strengthen Your DoD Authorization Journey  

Organizations should proactively approach their DoD authorization journey by adopting the following practical steps: 

1. Start With a Readiness Assessment
   Although optional, starting with a readiness assessment can allow you to identify and address gaps early, before your DISA assessment. 
   
   
2. Implement Integrity Monitoring Early in the Process
   Implementing tools that validate configurations and detect unauthorized changes can dramatically reduce findings. 
   
   
3. Automate Evidence Collection Where Possible
   Automation reduces burden, speeds up reviews, and creates defensible, consistent evidence. 
   
   
4. Establish a Continuous Compliance Operating Rhythm 
   Your continuous compliance operations should include: 
   
   • Monthly vulnerability management reviews 
   • Routine log validation 
   • Change-control audits 
   • Configuration baseline verification 
5. Align With DoD Zero Trust Expectations Now
   Even if not formally required, alignment with DoD Zero Trust Reference Architecture strengthens authorization packages and future-proofs systems. 

Moving Forward with DoD IL4/IL5 Authorization 

Achieving IL4/IL5 authorization may seem daunting, but with the right preparation and continuous monitoring strategy, it's fully achievable. Organizations that take a proactive, disciplined approach significantly increase their chances of successful authorization. 

 As DoD expectations evolve, understanding the authorization process and implementing a strong compliance operating model will be critical for long-term success. Contact us today to learn more about the process, requirements, and how to prepare.