확장된 외부보고서의 외부검증과 지배구조의 결합이 자발적 공시 품질에 미치는 영향

Prior studies have agreed that assuring extended external reports (EERs) can be considered a way to avoid the mistrust of stakeholders. However, little is known about the role of credibility-enhancing mechanisms for disclosed information in EERs such as sustainability reports, ESG reports, and integrated reports. To fill this void, this study has two objectives: (a) to examine the individual impact of internal corporate governance (CEO power, board activity) and external assurance (double assurance and BIG4 assurance) mechanisms on the disclosure quality of EERs, and (b) to test the complementary or substitute effects of the internal and external mechanisms on firms' disclosure quality. Based on a Korean sample of 342 firm-year observations from the period 2017–2021, the study tests and confirms both the direct and the bundling effects of different internal and external corporate information-enhancing mechanisms on the level of disclosure quality for their corporate EERs. The main empirical evidence of this article confirms that: (i) different individual mechanisms, such as CEO duality (serving as CEO and Chairman of the Board of Directors), board activity (number of meetings), double assurance (parallel implementation of third-party assurance and greenhouse gas emissions certification), and BIG4 assurance have a positive and direct impact on the level of disclosure quality of EERs; (ii) complementarities exist between CEO duality and double assurance, reinforcing the individual effect, and substitutive effects exist between CEO duality and BIG4 assurance. The interaction between BIG4 assurance and CEO duality have a significant negative effect on disclosure quality. Additional analysis shows that in the case of environmentally-sensitive industries, when BIG4 accounting firm is the assurance provider, the interaction between CEO duality and BIG4 assurance has a negative impact on the level of disclosure quality of EERs.