Author: Sangwha Shin(Chungnam National Univ.)

This study exploits the 2020 introduction of mandatory external audits for public-interest corporations with revenues of KRW 5 billion or more as a quasi-natural experiment to examine how the requirement affected these corporations' disclosure timeliness and re-disclosure behavior. Using a balanced panel of National Tax Service disclosure data (2018~2024) and a difference-in-differences design around the revenue threshold, we find a reduction in long-delay disclosures (32 days or more) among the treatment group, while re-disclosure frequency rises immediately after the reform and then gradually converges. This dynamic pattern suggests that external audits operate less by immediately reducing errors than by prompting the open correction of latent ones. Instrumental-variable estimates that account for actual audit uptake yield effects in the same direction but of larger magnitude, indicating that the identified effect is tied to genuine audit implementation rather than a mere change in nominal rules and that mandatory external audits can improve disclosure quality in the nonprofit sector.