If a taxpayer fails, neglects, or refuses to make his or her return as and when required by this chapter, the city treasurer is authorized to determine the amount of the tax payable under provisions of section 2-8-4 of this chapter, 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 twelve percent (12%) per year on the unpaid balance from the date any such taxes became due as provided in section 2-8-7 of this chapter. (Ord. 188, 10-19-2010)