OAR 150-305-0140: Interest on Deficiencies and Delinquencies

(1) Adjustment to statutory rate. For deficiencies and delinquencies owing on or after January 1, 2026, unless otherwise provided by law, every deficiency and delinquency arising under any law administered by the department will bear interest at the rate of eight percent annually. For historic interest rates, see section (4) of this rule. (2) Interest start date. The interest start date for deficiencies and delinquencies will be one day after the due date of the return, excluding extensions. (3) Interest periods. (a) An interest period is one full calendar day beginning with the interest start date. Interest will be computed on a daily basis. The daily rate is based on a 365-day year. (b) The daily interest rate is calculated by dividing the annual interest rate by 365 without rounding. (4) Interest rates. The following table shows interest rates used by the department to compute interest due from taxpayers on deficiencies and delinquencies. Percentage Rates. Effective date - Annual rate - Monthly rate - Daily rate Prior to January 1, 1969 — 6 — 0.5 — — January 1, 1969 — 8 — 0.6667 — — September 13, 1975 — 12 — 1.0 — — June 1, 1982 — 18 — 1.5 — 0.0493 August 1, 1986 — 17 — 1.4167 — 0.0466 January 1, 1987 — 16 — 1.3333 — 0.0438 January 1, 1988 — 11 — 0.9167 — 0.0301 January 1, 1993 — 8 — 0.6667 — 0.0219 January 1, 1995 — 10 — 0.8333 — 0.0274 January 1, 1999 — 9 — 0.75 — 0.0247 January 1, 2001 — 10 — 0.8333 — 0.0274 February 1, 2002 — 8 — 0.6667 — 0.0219 February 1, 2003 — 7 — 0.5833 — 0.0192 January 1, 2004 — 6 — 0.5 — 0.0164 January 1, 2005 — 5 — 0.4167 — 0.0137 January 1, 2006 — 7 — 0.5833 — 0.0192 January 1, 2007 — 9 — 0.75 — 0.0247 January 1, 2009 — 6 — 0.5 — 0.0164 January 1, 2010 — 5 — 0.4167 — 0.0137 January 1, 2013 — 4 — 0.3333 — 0.0110 January 1, 2017 — 5 — 0.4167 — 0.0137 January 1, 2018 — 5 — N/A — 0.0137 January 1, 2019 — 6 — N/A — 0.0164 January 1, 2021 — 4 — N/A — 0.0110 January 1, 2023 — 6 — N/A — 0.0164 January 1, 2024 — 8 — N/A — 0.0219 January 1, 2025 — 9 — N/A — 0.0247 January 1, 2026 — 8 — N/A — 0.0219 The daily interest rates shown above are rounded for illustrative purposes. Example 1: Tom filed a 2016 return reporting tax to pay of $500. He made a $500 payment on February 25, 2019. The interest start date is April 19, 2017, the first day after the due date of the return, which was April 18, 2017. Interest is computed on a daily basis as follows: 4/19/17-12/31/2018 (Annual interest rate / 365 days) x number of days x tax due (5% / 365) x 622 days x $500 = $42.57 1/1/2019-2/24/19 (Annual interest rate / 365 days) x number of days x tax due (6% / 365) x 55 days x $500 = $4.52 Total interest: $47.09