Exchange of information: treaty requires mutual tax information sharing with confidentiality and limited exceptions for enforcement purposes Article 25 mandates mutual exchange of information foreseeably relevant to implementing the Agreement or administering and enforcing domestic tax laws, including documents and certified copies, without restriction by residence or source provisions. Information received must be treated as secret and disclosed only to authorized persons for assessment, collection, enforcement, prosecution, appeals or oversight and used solely for those purposes, except where both States' laws permit other use and the supplying authority authorizes it. Competent authorities must develop consultation-based conditions and techniques for exchange. Limits preserve conformity with domestic law, unobtainable information, trade secrets or public policy, but do not permit refusal solely due to bank secrecy or fiduciary relationships.