4.03.090 Underpayment of tax, interest, or penalty – Interest.
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.
A. For the purposes of this section, the rate of interest to be charged to the taxpayer for tax periods prior to January 1, 2005, shall be an average of the federal short-term rate as defined in 26 U.S.C. Section 1274(d) plus two percentage points. The rate shall be computed by taking an arithmetical average to the nearest percentage point of the federal short-term rate, compounded annually, for the months of January, April, July, and October of the year immediately preceding the calendar year as published by the United States Secretary of the Treasury. The rate shall be adjusted on the first day of January of each year for use in computing interest for that calendar year. For tax periods prior to January 1, 2005, interest shall be computed from the last day of the month following the end of the reporting period and will continue to accrue until payment is made.
B. For tax periods after December 31, 2004, the director shall compute interest in accordance with RCW 82.32.050 as it now exists or as it may be amended.
C. If subsection B of this section is held to be invalid, then the provisions of RCW 82.32.050 existing as of the effective date of the ordinance codified in this section shall apply. (Ord. 5781 § 4, 2007; Ord. 5605 § 2, 2005; Ord. 5558 § 1, 2004; Ord. 5436 § 1, 2003.)