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Control Institute
Category: Access and Identity Management

Segregation of Duties Policy

Also known as: SoD, Separation of Duties, Separation of Duty, SoD Policy, SOD
Simply put

A Segregation of Duties Policy is a set of rules that divides critical tasks and responsibilities among different people so that no single individual can control an entire sensitive process on their own. The goal is to reduce the risk of fraud and error by ensuring that one person cannot initiate, approve, and review the same action. By spreading responsibilities across multiple people, organizations make it harder for any one individual to misuse a system.

Formal definition

A Segregation of Duties (SoD) Policy is a formal internal control that operationalizes the principle that no single user should hold sufficient privileges to misuse a system independently. It divides critical functions, typically initiation, approval, execution, and review, among distinct individuals or roles to prevent conflicts of interest and mitigate the risk of fraud, error, and unauthorized activity. In practice, SoD is implemented through role definitions, access provisioning rules, and periodic access reviews, and it is commonly evaluated as a control supporting audit and compliance objectives; the specific conflicting-duty combinations, enforcement mechanisms, and exceptions depend on organizational scope and risk assessment rather than a universal control set.

Why it matters

Segregation of Duties addresses one of the most persistent sources of internal risk: concentration of control. When a single individual can initiate, approve, and review the same action, there is no independent check to catch fraud, error, or unauthorized activity before it takes effect. By distributing critical responsibilities across different people or roles, an SoD policy introduces friction that makes misuse of a system substantially harder for any one person to carry out undetected. As NIST frames it, the underlying principle is that no user should be given enough privileges to misuse the system on their own.

Beyond fraud prevention, SoD is fundamentally about reducing conflicts of interest and catching honest mistakes. A second set of eyes at the approval or review stage can surface errors that the original actor would not identify. This is why SoD is treated as a foundational internal control rather than a specialized security feature, it supports the integrity of financial, operational, and access-management processes at once.

In a compliance context, SoD is commonly evaluated as a control supporting audit and certification objectives, and auditors and certification bodies frequently look for evidence that conflicting duties have been identified and addressed. It is worth noting, however, that an SoD policy does not by itself guarantee the absence of fraud or error; its effectiveness depends on how the conflicting-duty combinations are defined, how enforcement and exceptions are handled, and how consistently the policy is applied to the organization's actual scope and risk profile.

Who it's relevant to

Compliance and GRC Managers
SoD policies are a recurring focus in both SOC 2 examinations and ISO 27001 certification, where evidence that conflicting duties have been identified and controlled is often expected. GRC managers are typically responsible for defining conflicting-duty combinations, documenting exceptions and compensating controls, and ensuring the policy aligns with the organization's scope and risk assessment.
Auditors and Assessors
Auditors evaluate SoD as an internal control supporting audit and compliance objectives. In a SOC 2 Type II engagement they assess whether the control operated effectively over the review period, while ISO 27001 assessors consider how SoD is reflected in the ISMS and, where applicable, the selected reference controls. Assessment outcomes depend on the auditor or certification body, the defined scope, and the applicable criteria.
Security Engineers and IAM Teams
Those managing identity and access implement SoD through role definitions and access provisioning rules that prevent conflicting privileges from being granted to a single user. They also support the periodic access reviews used to detect and remediate overlapping access, which are central to keeping the policy effective over time.
Business Process and Finance Owners
Process owners in areas such as finance and operations rely on SoD to ensure that no individual can initiate, approve, and review the same action. They help identify which task combinations create conflicts of interest and, where full separation is impractical, work with control owners to define compensating controls.

Inside SoD

Purpose and Scope Statement
Defines why the policy exists and which processes, systems, roles, and organizational units it applies to. In most engagements the scope aligns with the boundaries of the SOC 2 examination or the defined ISMS scope under ISO 27001, since the policy only governs the functions it explicitly covers.
Identification of Conflicting Duties
Lists the combinations of responsibilities that should not reside with a single individual, such as separating the ability to authorize, execute, record, and reconcile a transaction. The specific conflicts vary depending on the organization's processes and risk assessment rather than following a single universal rule.
Role and Access Assignment
Describes how duties are distributed across roles and how access rights are provisioned to enforce those separations. This typically ties to identity and access management processes and, under ISO 27001, may be informed by relevant Annex A reference controls selected via the Statement of Applicability.
Compensating Controls for Small Teams
Addresses situations where full separation is impractical due to limited staff, specifying alternative or mitigating controls (such as independent review or increased monitoring). This is commonly relevant in smaller organizations where duties cannot be fully divided.
Monitoring and Review Provisions
Defines how conflicts are periodically reviewed, how exceptions are approved and documented, and how access is recertified. The frequency and rigor of review typically depend on scope, risk, and expectations set by the auditor or certification body.
Roles, Responsibilities, and Enforcement
Assigns ownership for maintaining the policy, approving exceptions, and handling violations, along with consequences for non-compliance. This clarifies accountability so the control can be evidenced during a SOC 2 examination or ISO 27001 audit.

Common questions

Answers to the questions practitioners most commonly ask about SoD.

Does SOC 2 or ISO 27001 mandate a specific segregation of duties policy?
Neither framework prescribes a single mandatory segregation of duties (SoD) policy in a fixed form. Under SOC 2, SoD-related expectations are typically addressed within the Security category (Common Criteria), and how they are implemented depends on the auditor's assessment and the scope of the engagement. Under ISO 27001, SoD is addressed through the Annex A reference controls, which are selected via the Statement of Applicability and informed by the organization's risk assessment. In most cases, the specific policy design is left to the organization to justify against its risks rather than dictated by the standard.
Is a segregation of duties policy alone enough to pass a SOC 2 examination or achieve ISO 27001 certification?
No. A written policy is only one element. A SOC 2 Type II examination assesses both the design and operating effectiveness of controls over a defined review period, so evidence that the SoD policy is actually followed is typically expected, not just its existence. A SOC 2 Type I assesses suitability of design at a point in time. For ISO 27001, certification depends on the overall ISMS meeting the clause 4 through 10 requirements and on the risk-based selection and operation of controls, not on any single policy document. A policy that is documented but not operating as intended would generally not, on its own, satisfy either framework.
How do we identify which duties should be separated when drafting the policy?
In most engagements, organizations start from their risk assessment to identify functions where a single individual performing conflicting tasks could enable fraud, error, or unauthorized change without detection. Common areas examined include the ability to both initiate and approve transactions, to develop and deploy code to production, and to grant access while also using that access. Depending on scope, the policy typically documents these conflict pairs and the controls that address them, so that the rationale can be evidenced to an auditor or certification body.
What can we do when the organization is too small to fully separate conflicting duties?
When staffing limits prevent full separation, organizations typically rely on compensating controls and document the rationale. Examples that are commonly used include independent review of activity, monitoring and logging, management oversight, and periodic reconciliation. For ISO 27001, this justification would generally be reflected in the risk assessment and Statement of Applicability. For SOC 2, the compensating controls and their operating effectiveness are typically what the auditor evaluates. The appropriateness of any approach depends on the auditor, certification body, scope, and applicable criteria.
What evidence is typically requested to demonstrate the policy is operating?
The specific evidence varies by auditor, certification body, and scope. In a SOC 2 Type II examination, evidence generally needs to cover the review period and may include access review records, approval workflows, change management records showing that development and deployment responsibilities are separated, and records of independent reviews. For an ISO 27001 certification audit, evidence typically supports that the selected controls are implemented and maintained within the defined ISMS scope. In both cases, the goal is to show the policy is applied in practice rather than only documented.
How should the segregation of duties policy be maintained over time?
Maintenance is typically tied to the organization's ongoing risk management and change processes. As roles, systems, and organizational structure change, conflict pairs and compensating controls may need to be reassessed. For ISO 27001, this aligns with the continual improvement and review activities within the ISMS requirements. For SOC 2, keeping the policy current supports its operating effectiveness across future review periods. Reviews are commonly performed on a defined cadence and after significant changes, though the frequency and triggers depend on scope and organizational decisions rather than a fixed rule.

Common misconceptions

Having a Segregation of Duties Policy guarantees compliance with both SOC 2 and ISO 27001.
The two frameworks assess controls differently. A SOC 2 report is an attestation examination performed by a licensed CPA firm under SSAE 18 that attests only to the controls and period covered, while ISO 27001 is a certification issued by an accredited certification body against the ISMS requirements in clauses 4 through 10, with controls selected via the Statement of Applicability. Mapping between the two is possible but partial, and satisfying one does not automatically satisfy the other.
A SOC 2 Type II report proves segregation of duties was never bypassed and that no breach could occur.
A SOC 2 Type II assesses both the design and operating effectiveness of controls over a defined review period whose length is set by scoping decisions. It attests only to the controls and period covered and does not guarantee freedom from breaches or that the control operated without exception outside that period.
There is a fixed, mandatory list of duties that every organization must separate.
The specific conflicting duties depend on the organization's processes, scope, and risk assessment. Qualified language is more appropriate than absolutes: which separations apply typically varies by engagement, and where full separation is impractical, compensating controls may be used instead.

Best practices

Derive the conflicting-duty combinations from a documented risk assessment and align the policy scope with the boundaries of your SOC 2 examination or defined ISMS, so the policy covers the functions actually being evaluated.
Enforce separations through role-based access provisioning and periodic access recertification, retaining evidence that reviewers can examine during a SOC 2 Type II period or an ISO 27001 audit.
Define and document compensating controls (such as independent review or heightened monitoring) for cases where full separation is impractical due to limited staffing.
Establish a formal, documented exception-and-approval process so any deviations from the policy are authorized, recorded, and reviewed rather than handled informally.
Assign clear ownership for maintaining the policy, approving exceptions, and remediating violations, and review the policy on a defined cadence set to your scope and risk.
When pursuing both frameworks, map segregation-of-duties evidence to the relevant Trust Services Criteria (Security/Common Criteria) and to the applicable ISO 27001 Annex A reference controls selected in your Statement of Applicability, recognizing the mapping is partial.