The link between auditor tax expertise and corporate tax avoidance is investigated in this study. Using a sample of Taiwanese listed firms from between 2005 and 2019, it is found that companies that hire auditor tax experts engage in a higher level of tax avoidance. The results also show that this association is more pronounced among firms that have subsidiaries registered in tax havens. The findings of this study show that this positive association between auditor tax expertise and corporate tax avoidance can be mitigated through the adoption of IFRS. This study makes a contribution to existing literature by using a unique Taiwanese setting to study the tax avoidance effect of auditor tax experts and the effect of a common tax avoidance technique have on tax savings.