Tax return confidentiality: disclosure barred without consent, with narrow exceptions for prosecution and authorised class-level publication. Disclosure of individual GST return information is prohibited without prior written consent and such information cannot be used in proceedings under the Act; access is limited to those engaged in collection, statistical compilation or computerisation for GST purposes, with an exception permitting prosecution-related access and authorised publication of aggregated class-level information where the Chief Commissioner deems it in the public interest.