73% of G20 companies obtained sustainability assurance in 2023: IFAC report

Nearly three-quarters of the world’s largest companies obtained assurance on at least part of their sustainability disclosures in 2023, according to new data released by the International Federation of Accountants (IFAC) and AICPA & CIMA. The findings, published in the fifth edition of The State of Play: Sustainability Disclosure and Assurance (2019–2023), reflect the growing importance of verified ESG reporting among global corporates.

The report reveals that 73% of companies from G20 countries sought assurance on their sustainability reporting in 2023, up from 69% the previous year and significantly higher than the 51% recorded in 2019. The majority of assurance engagements continue to be limited in scope.

Audit firms remain the dominant providers of sustainability assurance, accounting for 55% of engagements globally in 2023. However, this marks a slight decline from 58% in 2022. The report attributes this dip to structural changes, such as the consolidation of assurance reports in the European Union, which has led to fewer total reports but not fewer engagements. In contrast, countries like South Korea continue to see a higher volume of multiple reports per company, particularly related to greenhouse gas emissions.

“Auditors have extensive education requirements, adhere to strict independence rules and possess a deep and holistic view of an organisation’s business, processes and risk profile,” said Susan Coffey, CEO of Public Accounting at AICPA & CIMA. “That makes them ideal candidates to perform sustainability assurance engagements, and we’re seeing many boards and audit committees endorsing that view.”

Audit firms also increased their market share in several jurisdictions in 2023, with gains in the United States (from 23% to 28%), United Kingdom (+5 percentage points), South Africa (+4), and Singapore (+6).

The report also highlights that 98% of large companies globally now report some sustainability information, while 44% include it in their annual or integrated reports—a sharp increase from 18% five years ago. Companies that integrate sustainability data into financial reporting overwhelmingly rely on their statutory auditor for assurance.

“The largest global companies have responded well to voluntary systems of sustainability reporting and assurance, driven by investor demand,” said IFAC CEO Lee White. “With new global standards in place, regulators now have the toolkits to move from voluntary to mandatory disclosures over time. This shift will help ensure sustainability-related information achieves the same trust and rigour as financial reporting.”

Five jurisdictions saw double-digit increases in sustainability assurance in 2023—Hong Kong, Indonesia, Mexico, Russia, and Saudi Arabia—underscoring a global trend toward greater transparency and credibility in ESG reporting.