If a taxpayer fails, neglects, or refuses to make his return as and when required by this chapter, the Finance Director is authorized to determine the amount of the tax payable under provisions of CMC 3.70.040, and to notify such taxpayer of the amount so determined. The amount so fixed shall thereupon be the tax and be immediately due and payable, together with penalty and interest. Delinquent taxes, including any penalties, are subject to an interest charge of 12 percent per year on the unpaid balance from the date any such taxes became due as provided in CMC 3.70.070. (Ord. 16-07 § 1)