지속가능성 보고서 인증의 결정요인 분석: 이사회 특성을 중심으로

This study explores the determinants of external assurance in sustainability reporting among listed firms in South Korea, with a primary focus on the characteristics of corporate boards. In recent years, the global emphasis on corporate sustainability and ESG (Environmental, Social, and Governance) practices has significantly increased, driving corporate initiatives toward the voluntary publication of sustainability reports as a means of enhancing transparency, accountability, and stakeholder engagement. Despite the growing prevalence of such reports, concerns persist regarding their credibility due to their self-reported and voluntary nature. As a response to these concerns, external assurance by independent third parties has emerged as a strategically important mechanism to validate the accuracy and reliability of ESG disclosures. However, external assurance remains a voluntary choice in South Korea, highlighting the need to understand what internal corporate governance factors influence this decision. While prior international research—primarily focused on institutional settings in Europe and other stakeholder-oriented countries—has examined various determinants of sustainability report assurance, empirical evidence specific to the Korean context remains scarce. South Korea's relatively underdeveloped ESG disclosure infrastructure, coupled with voluntary assurance practices, necessitates a localized investigation into the internal governance mechanisms that drive assurance adoption. This study addresses that gap by empirically examining the influence of board characteristics on firms’ decisions to obtain external assurance for their sustainability reports. Specifically, the study investigates variables such as board size, gender diversity, independence (as measured by the proportion of outside directors), separation of the CEO and board chair roles, existence of a sustainability(or ESG) committee, board activeness (frequency of board meetings), and national diversity of directors. These factors are analyzed for their association with assurance adoption, using a sample of firms listed on the Korea Exchange that published sustainability reports between 2016 and 2023. The empirical results suggest that certain board attributes—namely board size, gender diversity, board independence, and the separation between the CEO and board chair—are significantly associated with the likelihood of adopting external assurance. Firms with larger boards are more likely to adopt assurance, as the inclusion of directors with diverse expertise and experiences facilitates more informed and multilayered decision-making on ESG reporting. Likewise, Firms with greater gender diversity tend to exhibit stronger responsiveness to ESG-related issues and stakeholder concerns, which increases their propensity to pursue credible assurance mechanisms. Similarly, firms with a higher proportion of independent directors or those that separate the roles of CEO and board chair are more likely to implement external assurance, reflecting enhanced governance monitoring and oversight. These findings suggest that the structure and composition of the board—particularly in terms of its size, independence and diversity—play a vital role in shaping firms’ ESG disclosure strategies and their efforts to enhance report credibility through assurance. Notably, the study did not find statistically significant relationships for board activeness, national diversity, or the presence of an sustainability(or ESG) committee, indicating that not all aspects of board composition exert equal influence. This study contributes to both academic literature and practical policy-making in several important ways. First, it enhances the theoretical framework underpinning ESG disclosure practices by empirically linking board governance to assurance decisions within the unique institutional context of South Korea. Second, it extends the body of research beyond the traditional focus on European or multinational firms, offering region-specific insights that can inform local ESG reporting standards and assurance guidelines. Third, the findings provide meaningful implications for practitioners and regulators as ESG disclosure reliability becomes a more prominent topic in corporate policy discourse. By identifying the governance-level determinants of assurance adoption, this study highlights the strategic role that board structure can play in reinforcing transparency and stakeholder trust in sustainability reporting. In summary, this research emphasizes the importance of internal governance mechanisms—particularly those embedded within board structure—in promoting the credibility of voluntary ESG disclosures through third-party assurance. As ESG continues to gain relevance in both domestic and global capital markets, understanding the governance factors that drive credible reporting practices is increasingly essential. This study offers a timely and contextually grounded contribution to that understanding.