The aim of mandatory rotation of audit firms by public companies is to preserve the independence of the external auditor and reduce errors and fraud associated with the auditing of financial statements. Nevertheless requiring this rotation periodically is a controversial subject, since it involves the commercial and professional relationship of auditors with their clients and the market for auditing. This study focuses on the effect of rotation on the reports issued by audit firms, comparing them before and after the mandatory rotation established by the Brazilian Securities Commission (CVM), effective as of 2004. For this purpose, the auditor´s report was analyzed on the financial statements of 151 listed companies for the period of 2003 to 2006 that changed audit firms as required by the CVM’s rules. According to the results, the rotation of independent auditors did not assure the preservation of independence, nor is there any evidence of an increase in the quality of auditing. However, it was noted that the requirement for periodic rotation led to reduced concentration in the auditing market, with increased participation of small audit firms.
Keywords: Auditing; auditor rotation; audit opinion; mandatory rotation.