This study addresses the international debate over whether the rotation of audit firms should be mandatory. Mandatory rotation rules have been adopted by the European Union, but have not been established in the United States. Proponents of the policy believe that a long tenure auditor-client relationship leads to the auditor building an excessive economic bond with the client which erodes auditor independence. Motivated by this claim, I build a theoretical model that compares auditor incentives to issue independent reports under the regimes with and without mandatory rotation. The model demonstrates conditions under which mandatory rotation could impair auditor independence, contrary to the popular view.