Sydney, July 09, 2025: The Association of Chartered Certified Accountants (ACCA) and Chartered Accountants Australia and New Zealand (CA ANZ) have jointly called for consistent application of the newly issued International Standard on Sustainability Assurance 5000 (ISSA 5000). The call comes amid rising global focus on credible and trustworthy sustainability reporting, especially as more countries mandate such disclosures for large businesses.
As part of their strategic alliance, the two professional accountancy bodies have published a practical guide titled A Case Study: Demystifying Materiality in accordance with ISSA 5000. The guide is designed to help assurance practitioners understand and apply the materiality principle under the new standard.
“The trust and confidence of investors, regulators and other stakeholders in sustainability assurance is vital if sustainability reporting is to be successful in bringing about a more sustainable approach to business. This guide is intended to support assurance practitioners in applying professional judgement when planning and performing sustainability assurance engagements under ISSA 5000. It’s critical that assurance practitioners focus on the most significant aspects of sustainability reporting, which are most likely to influence the decisions of intended users,” said Antonis Diolas, Head of Audit and Assurance at ACCA. 
Amir Ghandar, Reporting and Assurance Leader at CA ANZ, added, “Materiality is no longer a buzzword – it’s the backbone of credible sustainability assurance. This guide offers clarity where it’s most needed. As sustainability reporting and assurance become mandatory across jurisdictions, ISSA 5000 sets the global baseline – and this guide helps practitioners apply it with confidence.”
“Applying materiality in sustainability assurance isn’t just about numbers, it’s about understanding what truly matters to stakeholders. This guide shows how. The case study bridges the gap between theory and practice, helping assurance practitioners navigate the nuanced judgement calls required for materiality under ISSA 5000,” Ghandar noted.
The guide walks practitioners through a fictional assurance engagement, structured around Scope 1, 2, and 3 greenhouse gas (GHG) emissions, highlighting how professional judgement should be applied during the materiality stage. It also underlines the importance of documentation and allocating sufficient time to this critical phase of sustainability assurance.
ISSA 5000, developed by the International Auditing and Assurance Standards Board (IAASB), aims to strengthen trust in sustainability disclosures and curb greenwashing by providing a globally accepted framework for assurance engagements.
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