- ISA 620, Using the Work of an Auditor’s Expert – addresses circumstances in which an auditor employs an external specialist to obtain audit evidence.
- ISRE 2400 (Revised), Engagements to Review Historical Financial Statements – outlines responsibilities in review engagements performed primarily for smaller entities.
- ISAE 3000 (Revised), Assurance Engagements Other than Audits or Reviews of Historical Financial Information – sets a framework for assurance engagements that fall outside the scope of traditional audits or reviews.
- ISRS 4400 (Revised), Agreed-Upon Procedures Engagements – covers engagements in which procedures are performed and findings are reported without providing assurance.
Each amended standard now references the IESBA Code’s new section on external experts, ensuring that ethical considerations such as competence, objectivity, and the nature of the expert’s relationship with the engagement team are incorporated directly into the procedural requirements. The IAASB emphasized that the changes are limited in scope, affecting only those paragraphs necessary to eliminate inconsistencies and to direct practitioners to the newly issued ethical provisions.
Background to the Revisions
The move follows IESBA’s broader initiative to strengthen the Code in areas where professional accountants increasingly depend on specialized knowledge—for instance, valuations, actuarial calculations, or complex information-technology assessments. By specifying when and how practitioners must evaluate an expert’s qualifications, integrity, and potential conflicts of interest, the Code seeks to protect the public interest and reinforce confidence in audit and assurance engagements.
The IAASB’s alignment effort also supports its ongoing strategy of coordinating closely with ethics standard setters. According to the International Federation of Accountants, close cooperation between the two boards is intended to minimize duplication, reduce implementation costs, and help firms of all sizes apply standards consistently across jurisdictions.
Recent Fraud Standard Update Provides Additional Context
The current amendments follow another significant IAASB action taken in July 2025, when the Board approved a comprehensive revision of ISA 240, The Auditor’s Responsibilities Relating to Fraud in an Audit of Financial Statements. That earlier revision clarified auditor duties, mandated a fraud-focused approach to risk assessment, and introduced new transparency requirements for engagements involving publicly traded entities. While unrelated to external experts, the fraud project demonstrates the IAASB’s broader commitment to enhancing audit quality in response to stakeholder concerns.
Implementation and Next Steps
The IAASB has encouraged auditors, assurance practitioners, and regulators to review the updated text promptly. The amendments take effect in tandem with the effective date of the revised IESBA Code, allowing firms a unified timeline for adoption. Transitional guidance is available within each standard to help engagement teams integrate the ethical and technical requirements into their methodologies.
National standard setters, professional bodies, and oversight authorities are expected to incorporate the changes into their local frameworks. The IAASB indicated that no additional substantive revisions are planned at this stage, but it will monitor implementation feedback to determine whether further adjustments are necessary.
For practitioners, the primary impact will be the need to document evaluations of external experts more comprehensively, ensure alignment between engagement acceptance procedures and ethical considerations, and communicate any limitations or qualifications arising from the expert’s work to those charged with governance.
Crédito da imagem: Lee Charlie/Shutterstock.com
