Exchange of information: obliges broad cross-border tax data sharing for administration and anti-evasion purposes. Article 26 requires Contracting States to exchange information foreseeably relevant to administering or enforcing taxes under the Convention or domestic law, including to prevent avoidance or evasion. Information received must be kept secret and used only for specified tax assessment, collection, enforcement, prosecution, appeals or oversight purposes unless both States' laws permit other uses with supplying State authorization; disclosure in public court proceedings is allowed. Limits include no obligation to alter domestic laws, obtain unavailable information, or disclose trade or public policy-protected secrets. Requested States must nonetheless use available information-gathering measures even without domestic interest, and bank or fiduciary status does not justify refusal. Competent authorities shall consult to develop exchange methods.