This strategy paper reviews performance auditing practices conducted by the US Government Accountability Office (GAO) in the oversight of utility regulators. Identify areas, issues and practices of possible collaborations between GAO and the Federal Court of Accounts (TCU - Brazil) in works of performance auditing of the utility regulators. It clarifies the concept and some critical issues about performance auditing. It identifies exemplar works of both SAI´s in the oversight of the regulation of utilities. It describes how the US public administration is in many important respects like its Brazilian counterpart.