THE National Internal Revenue Code (Tax Code), as amended, authorizes the commissioner of Internal Revenue or his duly authorized representative to conduct audits, in light of the power of the Bureau of Internal Revenue (BIR) to assess and collect taxes. These audits are conducted by revenue officers who are clothed with a valid letter of authority (LoA).

Through the years, the BIR has prescribed time frames, i.e., generally 120 days, within which revenue officers should complete and issue a report on the audit investigation. In the past, the continuation of the audit after the lapse of the prescribed period may be challenged by the taxpayer, unless the LoA is revalidated. In this respect, it is important to determine the status of the LoA in unfinished investigations beyond the audit period since the Supreme Court has been consistent in ruling that an invalid LoA nullifies the resulting assessment (Republic of the Philippines v Robiegie Corp., GR 260261, Oct. 3, 2022). In this article, we unravel the rules on LoA revalidation and examine the significance of LoA revalidation today.