If any taxpayer fails, neglects, or refuses to make a return as and when required under this Chapter, the city finance director is authorized to determine the amount of tax payable, and by mail to notify the taxpayer of the amount so determined. The amount so fixed shall thereupon become the tax and be immediately due and payable. (Ord. 92-7 §12, 1992; Ord. A-657B §15, 1966. Formerly 6.02.150).