789.09 FAILURE TO MAKE RETURNS; INSUFFICIENT RETURNS; INVESTIGATION AND ASSESSMENT.
   If any public utility fails or refuses to make a return, either in whole or in part, or if the City Treasurer has reasonable ground to believe that any return made is so deficient as not to form the basis of a satisfactory assessment of the tax, he may proceed as he deems best to obtain information on which to base the assessment of the tax. The City Treasurer may by himself, or his duly appointed agent, make examination of the books, records and papers, and audit the accounts of any such public utility. After procuring such information as he may be able to obtain as to any public utility failing or refusing to make a return, the City Treasurer shall proceed to assess the tax and shall notify the public utility assessed of the amount of the tax.
(1961 Code Sec. 789.09)