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Green Board

Technical Update

Sustainability Assurance

Exposure Draft on ISSA 5000: General Requirements for Sustainability Assurance Engagements

Barley Fields

In this article, we provide an overview of the latest developments relating to the ongoing project undertaken by the International Auditing and Assurance Standards Board (“IAASB”) to develop a comprehensive standard for assurance on sustainability reporting. 

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Objective of the Project:


The IAASB is currently working on a project to develop an overarching standard for assurance on sustainability reporting with the following goals: 

  • Addressing the public interest need for a timely standard supporting consistent quality in sustainability assurance engagements. 

  • Applicability across all sustainability topics, disclosed information, and reporting frameworks. 

  • Accessibility for all assurance practitioners, including professional accountants and other professionals involved in assurance engagements.


This new standard will address (a) both limited and reasonable assurance, (b) cover the entire assurance engagement process, and (c) address priority challenges in sustainability assurance engagements.

The IAASB's efforts will leverage existing IAASB Standards and guidance, including:


  • ISAE 3000 (Revised) Assurance Engagements Other Than Audits or Reviews of Historical Financial Information;


  • ISAE 3410, Assurance Engagements on Greenhouse Gas Statements; and


  • the non-authoritative guidance on sustainability and other extended external reporting assurance engagements.


In the future, the IAASB plans to explore the development of a suite of standards for sustainability reporting assurance, offering greater specificity.


Project Timeline:


The project timeline below outlines current milestones, which may be subject to change as work in this area progresses.


July 2023 Updates


In June 2023, the IAASB approved an exposure draft (“ED”) for the International Standard on Sustainability Assurance (ISSA) 5000, titled "General Requirements for Sustainability Assurance Engagements" (“ED-5000”). The draft, along with related amendments to other standards, will be open for public comments from August 2, 2023, with a 120-day comment period.


The IAASB has been working on this new overarching standard for sustainability assurance engagements since the project proposal was approved in September 2022. In developing ED-5000, key considerations included:


  1. Meeting public interest objectives: ISSA 5000 aims to meet public needs with a timely, high-quality standard for all sustainability areas, information, and frameworks, accessible to all practitioners. 

  2. Addressing priority areas: ED-5000 comprehensively covers all aspects of assurance engagements, with a specific focus on six priority areas: (a) limited vs. reasonable assurance; (b) reporting criteria; (c) engagement scope; (d) evidence evaluation; (e) internal control within the entity; and (f) practitioner materiality. 

  3. Additional focus areas: During the finalisation of ED-5000, extra attention was given to (a) key definitions; (b) quality management; (c) consolidated sustainability information; (d) double materiality; (e) fraud considerations; (f) sustainability-specific examples; and (g) assurance report format and content. 

  4. Approach to drafting: The standard was created by integrating elements from existing IAASB standards and guidance, such as ISAE 3000 (Revised), ISAE 3410, and non-authoritative IAASB guidance on sustainability and extended external reporting assurance. Relevant ISAs were also referenced when needed to ensure the right level of detail while keeping ISSA 5000 overarching.


The IAASB is planning a comprehensive global outreach strategy during the ED-5000 comment period to engage with a wide range of stakeholders across regions and constituencies. This outreach aims to enhance the IAASB's understanding of technical, operational, and regulatory aspects impacting sustainability assurance engagements. The IAASB intends to provide an update and discuss feedback received from these outreach activities during its December 2023 meeting.



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