The adoption of International Financial Reporting Standards (IFRS) has become one of the most important accounting issues around the world. Taiwan Accounting Research and Development Foundation (TARDF) since early 2000’s gradually released or updated a number of important accounting standards to comply with IFRS. This process provides a natural experimental ground for researchers to examine the impact of accounting principle changes on companies’ choice of auditors. The adoption of new accounting standards not only influences the asset evaluation process but also affects companies’ accounting information systems. Engaging a specialist auditor can send a signal of high-quality financial reporting to outsiders, and companies may gain positive market reactions as a result. For example, as more assets and liabilities are measured at fair value under the new standards, auditors must deal with the complexities of auditing fair value measurements, and their expertise of such a process may help companies overcome the difficulties in complying with new accounting standards. That is, the implementation of complex accounting standards may increase the demand for auditors who specialize in a certain industry, transaction, or even account. Hence, this study examines how the adoption of new accounting standards influences companies’ choice of specialist auditors. By testing auditor switches around the adoption of TSFAS No. 35, No.34 and No. 36, we find that the more a company is expected to be affected by IFRS-based standards, the more likely it may choose an account specialist auditor when it adopts these new standards. The results are more significant at the individual level since an individual auditor is more likely to possess expertise than audit firms as a group, since professional judgments rely on individual auditor’s knowledge and task-specific experience. Our results also suggest that companies with higher earnings management incentives are less likely to engage industry specialist auditors, even when they are influenced by the adoption of new accounting standards. However, the influence of companies’ earnings management incentives on their choice of specialist auditors is affected by the complexities of new standards adopted.