Assurance Provider Rotation and Sustainability Assurance Quality

ABSTRACT This study examines the relationship between assurance provider rotation and sustainability assurance quality using an international sample of 604 companies over the period 2011–2017. We find that provider rotation is positively associated with both breadth and depth of assurance statements, suggesting that switching assurers is linked to higher overall sustainability assurance quality. However, when companies switch from nonaccounting to accounting providers, assurance quality decreases, particularly in statement breadth and to a lesser extent in depth. Additional analyses indicate that these rotation effects reflect structural heterogeneity between provider types rather than dynamic improvements following a switch, with quality benefits emerging gradually as new assurers establish their engagement approaches. The findings advance understanding of how market structure and provider characteristics shape sustainability assurance quality and provide timely insights for standard setters and regulators developing new frameworks for sustainability reporting and assurance.