If the fiscal year of any taxpayer, as reflected by the books of his business, is not based upon the calendar year, with the assent of the finance director first obtained, such taxpayer may apply for occupation license, make returns, and pay his license fee or tax on or before 45 days after the close of his fiscal year, as shown by the method of keeping the books of the business, in the same manner as provided in BMC 6.06.070(B), except as changed in this chapter. [Code 1980 at § 15.04.090].