In March, the Public Company Accounting Oversight Board held hearings about whether to require public companies to change — or “rotate” — their external auditor periodically. Meanwhile, the European Union is proposing to require mandatory rotation every six or 12 years, and the lower house of the Dutch Parliament recently voted to require auditor rotation every eight years.

At the PCAOB hearings, various investor advocates and pension funds argued in favor of mandatory rotation. They found fault with the lengthy relationships between many auditors and the companies they audit — the auditors of almost 36% of all companies in the Russell 1000 have held that position for 21 years or more. According to the supporters of auditor rotation, this coziness creates a potential conflict of interest: an auditor’s desire to maintain a good relationship with its client could conflict with its duty to rigorously question the client’s financial statements.

Mandatory auditor rotation could reduce this conflict. Since auditors would know that their engagement would come to an end after a fixed period, they would have less incentive to curry favor with management. At the same time, mandatory rotation could encourage existing auditors to perform more thorough audits, because the firm would fear that a new auditor would expose any previous errors or omissions.

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