All taxes due under this chapter but not timely paid as required are subject to a penalty of 10 percent of the tax due. Interest shall accrue on the tax due including penalties and interest at the rate of 12 percent per year from the date such taxes are due. Partial payments shall be applied first to accrued penalties, then to interest and then to principal. A payment is timely paid when mailed to the borough postage prepaid bearing a postmark date no later than the due date. [Ord. 91-03 §2, 1991. Formerly §3.26.090].