Refusal to Assist in Tax Information Exchange: permitted for nonconforming requests, privilege, or public policy conflicts. The requested State may decline assistance where a request does not conform to the agreement, where domestic means have not been exhausted absent disproportionate difficulty, or where disclosure would violate public policy. The State need not supply trade or professional secrets, confidential client-legal representative communications produced for legal advice or proceedings, or perform measures contrary to its laws and practices. A request cannot be refused because the tax claim is disputed, the requested State is not required to obtain information the requester could not obtain domestically, and omission of some Article 5 details is not sole grounds for refusal if the information can otherwise be provided.