Exchange of information expanded to permit mutual tax information sharing with confidentiality and use restrictions for administration and enforcement. Article 26 is replaced to require competent authorities to exchange foreseeably relevant information, including documents, for application of the Convention or administration and enforcement of domestic tax laws, treat such information as secret and limit disclosure to persons or authorities concerned with assessment, collection, enforcement, prosecution, appeals or oversight, permit other uses only with legal allowance in both States and supplying authority authorisation, preserve limits against contravening domestic law or revealing trade secrets or information contrary to public policy, and obligate information gathering even absent domestic interest, including where information is held by banks or fiduciaries.