Wash. Admin. Code § 458-18-220
(3) Interest rates. The following rates are applied to the amount of the judgment or the amount of the refund, until paid:
| Year taxpaid | AuctionYear | Rate | |
| 1984 | 1983 | 9.29% | |
| 1985 | 1984 | 11.27% | |
| 1986 | 1985 | 7.36% | |
| 1987 | 1986 | 6.11% | |
| 1988 | 1987 | 5.95% | |
| 1989 | 1988 | 7.04% | |
| 1990 | 1989 | 8.05% | |
| 1991 | 1990 | 8.01% | |
| 1992 | 1991 | 5.98% | |
| 1993 | 1992 | 3.42% | |
| 1994 | 1993 | 3.19% | |
| 1995 | 1994 | 4.92% | |
| 1996 | 1995 | 5.71% | |
| 1997 | 1996 | 5.22% | |
| 1998 | 1997 | 5.14% | |
| 1999 | 1998 | 5.06% | |
| 2000 | 1999 | 4.96% | |
| 2001 | 2000 | 5.98% | |
| 2002 | 2001 | 3.50% | |
| 2003 | 2002 | 1.73% | |
| 2004 | 2003 | 0.95% | |
| 2005 | 2004 | 1.73% | |
| 2006 | 2005 | 3.33% | |
| 2007 | 2006 | 5.09% | |
| 2008 | 2007 | 4.81% | |
| 2009 | 2008 | 2.14% | |
| 2010 | 2009 | 0.29% | |
| 2011 | 2010 | 0.21% | |
| 2012 | 2011 | 0.08% | |
| 2013 | 2012 | 0.15% | |
| 2014 | 2013 | 0.085% | |
| 2015 | 2014 | 0.060% | |
| 2016 | 2015 | 0.085% | |
| 2017 | 2016 | 0.340% | |
| 2018 | 2017 | 1.130% | |
| 2019 | 2018 | 2.085% | |
| 2020 | 2019 | 2.040% | |
| 2021 | 2020 | 0.165% | |
| 2022 | 2021 | 0.050% | |
| 2023 | 2022 | 2.50% | |
| 2024 | 2023 | 5.26% | |
| 2025 | 2024 | 5.115% | |
| 2026 | 2025 | 4.145% |
[Statutory Authority: RCW 84.34.065, 84.34.141, 84.34.360, and 84.69.100. WSR 26-01-183, s 458-18-220, filed 12/23/25, effective 1/1/26; WSR 24-24-089, s 458-18-220, filed 12/3/24, effective 1/1/25; WSR 24-03-001, § 458-18-220, filed 1/3/24, effective 1/3/24; WSR 23-01-007, § 458-18-220, filed 12/7/22, effective 1/1/23; WSR 22-04-028, § 458-18-220, filed 1/24/22, effective 1/1/22; WSR 21-01-210, § 458-18-220, filed 12/23/20, effective 1/1/21; WSR 20-02-056, § 458-18-220, filed 12/24/19, effective 1/1/20; WSR 19-02-058, § 458-18-220, filed 12/27/18, effective 1/1/19; WSR 18-01-147, § 458-18-220, filed 12/20/17, effective 1/1/18; WSR 17-01-162, § 458-18-220, filed 12/21/16, effective 1/1/17; WSR 16-01-035, § 458-18-220, filed 12/9/15, effective 1/1/16; WSR 15-01-166, § 458-18-220, filed 12/23/14, effective 1/1/15; WSR 14-01-059, § 458-18-220, filed 12/13/13, effective 1/1/14; WSR 13-02-053, § 458-18-220, filed 12/26/12, effective 1/1/13; WSR 12-01-040, § 458-18-220, filed 12/13/11, effective 1/1/12. Statutory Authority: RCW 84.69.100. WSR 11-02-017, § 458-18-220, filed 12/29/10, effective 1/1/11; WSR 10-07-038, § 458-18-220, filed 3/10/10, effective 4/10/10; WSR 08-24-094, § 458-18-220, filed 12/2/08, effective 1/2/09; WSR 07-24-037, § 458-18-220, filed 11/30/07, effective 12/31/07; WSR 06-21-059, § 458-18-220, filed 10/16/06, effective 11/16/06; WSR 05-22-096, § 458-18-220, filed 11/1/05, effective 12/2/05; WSR 04-24-101, § 458-18-220, filed 12/1/04, effective 1/1/05; WSR 03-24-014, § 458-18-220, filed 11/20/03, effective 12/21/03; WSR 02-23-081, § 458-18-220, filed 11/19/02, effective 12/20/02; WSR 02-03-039, § 458-18-220, filed 1/8/02, effective 2/8/02; WSR 00-24-106, § 458-18-220, filed 12/6/00, effective 12/31/00; WSR 99-24-033, § 458-18-220, filed 11/23/99, effective 12/24/99. Statutory Authority: RCW 84.08.010, 84.08.070 and 84.69.100. WSR 99-01-066, § 458-18-220, filed 12/14/98, effective 1/1/99; WSR 98-01-177, § 458-18-220, filed 12/23/97, effective 1/1/98; WSR 97-02-068, § 458-18-220, filed 12/31/96, effective 1/1/97; WSR 96-01-093, § 458-18-220, filed 12/19/95, effective 1/1/96; WSR 95-06-044, § 458-18-220, filed 2/24/95, effective 3/27/95; WSR 94-05-063, § 458-18-220, filed 2/11/94, effective 3/14/94. Statutory Authority: RCW 84.08.010 and 84.69.100. WSR 93-06-096, § 458-18-220, filed 3/3/93, effective 4/3/93; WSR 92-17-027, § 458-18-220, filed 8/11/92, effective 9/11/92; WSR 91-15-024, § 458-18-220, filed 7/11/91, effective 8/11/91. Statutory Authority: RCW 84.69.100 and 84.08.010(2). WSR 89-10-067 (Order PT 89-6), § 458-18-220, filed 5/3/89; WSR 88-07-003 (Order PT 88-3), § 458-18-220, filed 3/3/88. Statutory Authority: RCW 84.69.100 as amended by 1987 c 319 and 84.08.010(2). WSR 87-19-141 (Order PT 87-7), § 458-18-220, filed 9/23/87.]