Purpose - This study was carried out in two stages. This study investigates (1) whether a negative relationship between management risk and effective tax rates is intensified in owner-manager firms, and (2) whether such a relation is intensified in firms with high growth. Design/Methodology/Approach - The sample of this study includes 2,622 firm-year observations drawn from the KIS-VALUE database. The sample was obtained from firms listed on the Korean Stock Exchange from 2011 to 2018. Findings - The results of the study are as follows. First, the results show that a negative relationship between management risk and effective tax rates is intensified in firms with an owner-manager. We infer that owner-manager companies have a stronger incentive to secure internal funds by reducing tax payments. Second, the result provides that in firms with high growth, a negative relationship between management risk and effective tax rates is intensified. The result indicates that high growth companies have a stronger incentive to secure internal funds by reducing tax payments. Research Implications - The results of this study will help tax authorities screen the behavior of firms in tax reduction as well as company tax strategies.