This research investigates into the relevance between corporate governance variables and tax planning. Our research subjects are the listed companies in the general industry between 2017 and 2019 in Taiwan. We use panel threshold regression model with fixed effects to undertake regression analysis. The results show that factors such as larger-sized boards, independent directors, and larger share-holding proportions of the major shareholders can effectively foster the positive, instead of improper, corporate tax planning. In addition, the larger the executive ownership and compensation is, the less likely the improper tax planning will take place or the more likely the top managers will arrange positive tax planning. Good or bad corporate governance will have significant influence on good or bad tax planning. Good corporate governance mechanism can effectively monitor and encourage executive managers while bad corporate governance will encourage them to use improper tax planning to pursue illegal personal profit-making, doing corporations harm.