The AICPA has issued nonauthoritative guidance addressing the use of current auditing standards for audits of prior periods.
According to Technical Question and Answer (TPA) 8100.03, when an auditor is engaged to perform an audit of financial statements that are as of or for a period that ended prior to the effective date of the clarified auditing standards, an auditor may perform and report on an entity’s prior-period financial statements using the clarified auditing standards even though the standards were not effective for that prior period.
