Does better sustainability reporting assurance lead to better reporting? Evidence from the EURO STOXX 600

Given recent debate on the quality of sustainability disclosure and its determinants, this study examines the role of sustainability reporting assurance in improving the quality of sustainability reporting. Drawing from a sample of 111 companies listed in the EURO STOXX 600 and located in Italy, France and Spain - where sustainability reporting assurance is mandatory - we find that the quality of the sustainability assurance process generally enhances the quality of assured reports. In essence, a well-executed assurance process positively impacts on sustainability reports’ readability, completeness and standardization, thereby enhancing their overall quality. Our study has important implications for the literature on the quality of sustainability disclosure and the role of mandatory assurance, offering important insights for policy makers in light of the forthcoming implementation of the Corporate Sustainability Reporting Directive (CSRD), which requires assurance of mandatory sustainability reports throughout Europe.