Any information gained as the result of any returns, investigations, hearings or verifications required or authorized by this chapter shall be confidential except for official purposes, or except in accordance with proper judicial order. The Clerk-Treasurer or his delegate may furnish the Bureau of Internal Revenue, Treasury Department of the United States with copies of the returns filed. Any person divulging such information, except as hereinbefore authorized, shall be subject to the penalty provided in § 33.99.