(a) Whenever a penalty charge for late payment on a utility charge, assessment charge, or any other charge of the City shall be due the City of Kenai, such penalty rate shall be computed in the amount of ten percent (10%) on the total sum due.

(b) Whenever interest is due on an unpaid account, charge, or assessment of any kind to the City of Kenai, the rate of such interest shall be computed at the rate of ten percent (10%) per annum, except that interest charged on special assessment districts shall be in accordance with provisions of Title 16 of the City Code.

(c) Unless otherwise specified, a penalty charge shall be due on any sum, charge, or payment not paid to the City within the first twenty-five (25) days after due date.