Exchange of Information requires mutual provision of foreseeably relevant tax information subject to confidentiality and limited exceptions. Article 26 requires competent authorities to exchange information foreseeably relevant to implementing the Agreement or administering and enforcing domestic tax laws, including documents, and obliges a requested State to use its information gathering measures even if it has no domestic need for the information. Information received must be treated as secret and disclosed only to persons or authorities concerned with tax assessment, collection, enforcement, prosecution, appeals or oversight and used solely for those purposes unless both States' laws and the supplying authority permit other uses. Limitations include no requirement to alter domestic law or supply unattainable information or to disclose trade secrets or information contrary to public policy; bank or fiduciary status does not bar disclosure.