Rules of Behavior is a net-new requirement in R3 that closes out the Planning (03.15) family, and it puts the user's obligations in writing with a signature to match. Rules of Behavior (03.15.03) has four (4) parts: establish rules describing responsibilities and expected behavior for system usage and protecting Controlled Unclassified Information (CUI), provide those rules to individuals who require access, receive a documented acknowledgement before authorizing access, and review and update the rules on a defined frequency. Per the NIST discussion, rules of behavior represent a type of access agreement for system users, and organizations differentiate between rules that apply to privileged users and rules that apply to general users.
A common difficulty with this requirement is assuming an acceptable use policy buried in the employee handbook covers it. This requirement is new for R3, and the sequencing matters: the acknowledgement must be received before access to CUI and the system is authorized, not at the next annual training cycle. That timing is what most onboarding processes get wrong.
Where things stand for companies facing the transition from NIST 800-171 R2 to R3:
The following is reproduced verbatim from NIST 800-171 R3, requirement 03.15.03 Rules of Behavior. Only the formatting has been adjusted for readability. This requirement has four (4) lettered parts:
The source control is PL-04 from NIST 800-53. The bracketed assignment in part d is the Organization-Defined Parameter (ODP): the review and update frequency. Per the NIST discussion, organizations consider rules of behavior for the handling of CUI based on individual user roles and responsibilities. You can read the requirement directly at NIST 800-171 R3, 03.15.03 (p. 69).
One (1) value sits inside this requirement. Depending on your contract, your organization may be permitted to define it. Organizations in the DIB subject to CMMC are not, because the DoD has defined it as policy.
The value below comes from Attachment A of the DoD Chief Information Officer (CIO) memorandum dated 10 April 2025 (signed David W. McKeown). The memo identifies each parameter by requirement sub-part, while NIST 800-171A R3 identifies the same parameter by ODP number. Both identifiers appear below so you can match your System Security Plan (SSP) language to either document.
The memo states that its values "will be updated as necessary," so confirm against the current version before writing them into policy.
NIST 800-171A R3 breaks 03.15.03 into six (6) assessment objectives: one (1) Organization-Defined Parameter (ODP) and five (5) determination statements. These AOs are:
Establishing the rules (a), providing them (b), and receiving the acknowledgement (c) are three separate objectives, so the chain has to be complete. If you are a DoD contractor, the ODP is specified. Per the DoD-specified ODP value in ComplianceForge's NIST 800-171 R3 Transition Guide, the review and update frequency (ODP[01]) is at least every twelve (12) months, or when there are significant incidents or significant changes to risks. The full guidance on assessment methods and objects, is in NIST 800-171A R3, 03.15.03 (p. 91).
Examine: security planning policy and procedures; rules of behavior for system users; signed acknowledgements of rules of behavior; records for rules of behavior reviews and updates; system security plan.
Interview: personnel with rules of behavior establishment, review, and update responsibilities; personnel with literacy training and awareness responsibilities; personnel with role-based training responsibilities; authorized users of the system who have signed rules of behavior; personnel with information security responsibilities.
Test: processes for establishing, reviewing, disseminating, and updating rules of behavior; mechanisms for supporting or implementing the establishment, dissemination, review, and update of rules of behavior.
03.15.03 is net new for R3 and has no corresponding requirement in NIST 800-171 R2:
Mapped against the six (6) AOs, all six (6) are net new (significant effort), with none direct, indirect, or unmapped. The source control, PL-04, was a non-federal organization (NFO) control in R2, meaning it was expected of contractors but not directly assessed. R3 pulls it into the assessable requirement set, so elements of your existing practice may satisfy the intent, but there is no R2 assessment objective to transition from. Expect an assessor to look for the rules, the distribution, and the signed acknowledgements as distinct artifacts.
Source Control in NIST 800-53 R5:
Secure Controls Framework (SCF) Crosswalk
Organizations running a single control set across multiple frameworks can satisfy 03.15.03 through the following SCF controls:
The crosswalks from NIST 800-171 R3 and NIST 800-171A R3 to the SCF are available at no cost through the SCF Set Theory Relationship Mapping (STRM): https://securecontrolsframework.com/start-here/set-theory-relationship-mapping-strm. The STRM also carries the relationship type for each mapping (Equal, Subset Of, Intersects With), which tells you whether an SCF control fully satisfies the requirement or only part of it. Mapping above taken from SCF 2026.3.
The pitfalls for this net-new requirement are about sequencing and evidence, each of which needs documented evidence of due diligence and due care such as policies, standards, procedures, and configuration screenshots:
Reasonable objective evidence for an assessment is often subjective. The following examples of evidence to address NIST 800-171 R3 03.15.03 are sourced from the SCF Evidence Request List (ERL), available at https://securecontrolsframework.com/free-content/scf-download. These ERL artifacts are mapped to NIST 800-171 R3 03.15.03 through SCF controls. They establish a starting point for discussions on what an organization needs to have for evidence of due diligence and due care to withstand external scrutiny by an assessor or regulator.
Alongside these, keep the System Security Plan (SSP) narrative for 03.15.03 recording the ODP values you adopted.
With all six (6) AOs net new, 03.15.03 is a significant lift, though the artifacts themselves are straightforward. A realistic sequence:
What value does the DoD require for the organization-defined parameter in NIST 800-171 R3 03.15.03? R3 leaves the value to the organization. For the DIB, the DoD set it in the 10 April 2025 memorandum under ODP identifier 03.15.03.d: at least every 12 months, or when there are significant incidents or significant changes to risks.
How many assessment objectives does NIST 800-171 R3 03.15.03 have? NIST 800-171A R3 breaks 03.15.03 into six (6) assessment objectives: one (1) Organization-Defined Parameters (ODPs) and five (5) determination statements. An assessor works through each one separately, so each needs its own evidence.
Which NIST 800-53 R5 control does NIST 800-171 R3 03.15.03 come from? PL-04.
Where does NIST 800-171 R3 03.15.03 sit in the NIST 800-171 R3 Kill Chain? Phase 6b, Identify Compliance Stakeholders. The Kill Chain is a phased model for sequencing R3 implementation, and it assigns this requirement to that phase.
03.15.03 Rules of Behavior establishes rules for system usage and protecting CUI, provides them to everyone who needs access, collects a documented acknowledgement before access is authorized, and reviews the rules on a defined frequency. It is net new for R3, so all six (6) objectives are new work, though PL-04 was an expected control under R2. The recurring problem is granting access first and collecting signatures later. Write CUI-specific rules, differentiate privileged from general users, capture the acknowledgement before access is granted, keep the signed records, and review at least every twelve months.
Authoritative sources:
Authoritative sources:
This guide reproduces U.S. Government text from NIST 800-171 R3 and NIST 800-171A R3 and references the DoD ODP memorandum of 10 April 2025. It is educational, not legal or assessment advice. Last reviewed: 2026-09-22.
