All income tax returns filed under this chapter, or copies thereof on file with the State Department of Revenue, shall be open to inspection by officials or duly authorized agents of the Bureau of Internal Revenue lawfully charged with the administration or enforcement of the federal income tax law or officials or duly authorized agents lawfully charged with the administration or enforcement of the income tax laws of any state which allows the State of Alabama or its authorized officials or agents a like privilege, for the purpose of administration and enforcement of such laws, subject to the conditions hereinafter included. The inspection shall only be permitted under such rules and regulations as may be prescribed by the Commissioner of Revenue.