If, upon examination of any returns, or from other information obtained by the director, it appears that a tax or penalty less than that properly due has been paid, the director shall assess the additional amount found to be due and shall add thereto interest on the tax only. The director shall notify the person by mail of the additional amount, which shall become due and shall be paid within 30 days from the date of the notice, or within such time as the director may provide in writing. (Ord. 6814 § 2 (Exh. B), 2021.)