This FAQ focuses on the relevance of International Standard on Sustainability Assurance (ISSA) 5000 to assurance on sustainability reports to be issued in the European Union. It provides a high-level understanding of how ISSA 5000 can support consistent, high-quality sustainability assurance engagements in the EU—enhancing users’ confidence in sustainability information prepared in accordance with the European Sustainability Reporting Standards (ESRS).

More and more, SME clients are turning to their accountants not just for compliance, but for insights, clarity, and strategic partnership as uncertainty, competition, and complexity continue to shape their business environments. As a result, many practitioners find themselves asking: “How do I move from tax and reporting to deeper advisory services without feeling like a salesperson?”

The PAO Strategy Planning Toolkit directly supports our Strategy and Member Value Proposition helps PAOs succeed in delivering on their mandates, strengthening governance, and building relevance. Whether your PAO is navigating
regulatory reform, digital transformation, or evolving public expectations, a clear and actionable strategy is essential.

This publication is relevant to all professional accountants, whether in business or in public practice, and sustainability assurance practitioners (SAPs). It provides answers to common questions on:

This publication highlights key aspects of the IESSA that illustrate its proportionality, while the IESSA also provides a robust global ethics and independence baseline for sustainability assurance engagements (SAEs). The proportionality of the IESSA enables it to support the performance of SAEs for entities of all sizes, thereby underpinning public trust in those engagements.

The publication is especially geared towards facilitating the implementation of the IESSA by SAPs that are small and medium practices (SMPs).

This Frequently Asked Questions document addresses the applicability of ISSA 5000, ISAE 3000 (Revised), and ISAE 3410 for sustainability assurance engagement after the effective date of ISSA 5000 (December 2026). It is intended to assist with adoption and consistent implementation of ISSA 5000.

These extracts of the ISSA 5000 feature the material that is relevant to limited assurance and reasonable assurance engagements. They were prepared in response to requests from stakeholders to be able to separately view the material.

This Staff Alert draws the attention of professional accountants in public practice, particularly accounting firm leadership, to important ethics and independence provisions in the International Code of Ethics for Professional Accountants (including International Independence Standards) (the Code) that remain applicable both before and after PE investment in an accounting firm.