Tax information confidentiality limited to tax authorities and use for assessment, enforcement, appeals, with restricted onward disclosure. Article 9 requires that information obtained under the treaty be treated as confidential, disclosed only to persons or authorities within the receiving Contracting Party concerned with assessment, collection, enforcement, prosecution, or appeals for the taxes covered, and used solely for those purposes; it allows disclosure in public court proceedings or judicial decisions and forbids onward disclosure or transfer to other persons, entities, authorities, or jurisdictions without the Requested Party competent authority's express written consent.