Exchange of information: competent authorities may obtain and share tax relevant information, subject to confidentiality and legal exceptions. Article 27 mandates that competent authorities exchange foreseeably relevant information, including documents or certified copies, for administering the Agreement and domestic tax laws; the requested State must use its information gathering measures even if it lacks a domestic interest, subject to limits. Information received is to be kept secret and disclosed only to persons or authorities involved in tax assessment, collection, enforcement, prosecution, appeals or oversight, and used solely for those purposes, with permitted disclosure in public court proceedings. No obligation arises to override domestic law or disclose protected trade secrets or information contrary to public policy.