Separate conflicting duties and areas of responsibility to reduce opportunities for unauthorised modification or misuse of information.
Also written as A5.3, Annex A 5.3, ISO 27001:2022 A.5.3, ISO27001 A.5.3.
Segregation of duties is one of 37 Organisational Controls in ISO/IEC 27001:2022 Annex A. Separate conflicting duties and areas of responsibility to reduce opportunities for unauthorised modification or misuse of information. Organisational controls are judged on governance rather than tooling: an auditor wants a named owner, an approval trail, and evidence the control is exercised on a defined cadence rather than written once and filed.
When preparing your Statement of Applicability (SoA) for A.5.3, gather artefacts such as:
If you run more than one framework, the same evidence usually satisfies all of them. A.5.3 aligns with:
SOC 2: CC5.1 Control activities mitigating risk, CC6.3 Role-based access and least privilege
NIST CSF 2.0: GV.RR-02 Roles, responsibilities and authorities, PR.AA-05 Access authorization and least privilege
A.5.3 consolidates the following ISO 27001:2013 control(s): A.6.1.2. If you are transitioning an existing ISMS, map your prior evidence for these to A.5.3 in your updated SoA.
Annex A controls are not mandatory in the abstract. Clause 6.1.3 requires you to compare your risk treatment plan against Annex A and justify, in the Statement of Applicability, any control you exclude. If your risk assessment surfaces a risk that A.5.3 addresses, excluding it needs a documented, risk-based rationale that an auditor will test.
In two passes. First design: does a documented control exist, is it owned, and does it address the risk? Then operating effectiveness: the auditor samples records from across the audit period to confirm the control actually ran. A Stage 2 audit will typically pull several samples, so evidence that only exists for the month before the audit is a common finding.
ISO 27001 sets no fixed interval — it requires review at "planned intervals" and after significant change. Annual review is the norm most certification bodies expect, with an out-of-cycle review triggered by incidents, major system changes, restructures, or new regulatory obligations. Record the review date and outcome either way; an undated control is treated as unreviewed.
A.5.3 aligns with SOC 2 CC5.1, CC6.3 and NIST CSF GV.RR-02, PR.AA-05. Evidence gathered for one framework will usually satisfy the others, which is the basis for a test-once, satisfy-many control library.
A.5.3 consolidates 1 control(s) from the 2013 edition: A.6.1.2. When transitioning, re-point the existing evidence rather than rebuilding it — the underlying requirement has not changed materially.