Examining the extent of and determinants for sustainability assurance quality: The role of audit committees

This study examines the extent of and determinants for sustainability assurance quality. Data comprise sustainability assurance statements published by the top 100 listed companies in Australia and New Zealand from 2017 to 2019. The findings indicate that Australian companies lead their New Zealand counterparts in sustainability assurance. Although sustainability reporting has risen, assurance rates remain significantly low. Accountants dominate the market, and companies prefer to use their own auditors for sustainability assurance work. Sustainability assurance quality is poor and does not vary significantly among Australian and New Zealand companies. Low-quality sustainability assurance plays a limited role in mitigating potential stakeholder–agency conflicts. The regression analysis indicates that audit committee characteristics such as members' independence, industry/market expertise, and attending meetings enhance sustainability assurance quality, whereas audit committee size has no affect. These findings suggest that audit committee characteristics such as independence, industry expertise, and regular meeting attendance have the potential to reduce stakeholder–agency conflicts by improving the quality of sustainability statement assurance. Our findings build on the sustainability assurance literature by exploring current trends in sustainability assurance practices in Australia and New Zealand where corporate governance codes have been recently revised. Further, these findings are timely given recent changes in standards (International Standard on Assurance Engagements ISAE] 3000 and Global Reporting Initiative GRI]). Our study contributes to the audit committee literature and sheds light on the role played by audit committee characteristics on sustainability assurance statement quality. The study findings potentially offer useful insights for practitioners, standard setters, and regulators.