1. (1) Introduction. This rule provides the rates of inflation discussed in RCW 84.34.330 and WAC 458-30-550 Exemption—Removal or withdrawal. It also explains the department of revenue's (department) obligation to annually publish a rate of inflation and the manner in which this rate is determined.

2. (2) General duty of department - Basis for inflation rate. Each year the department determines and publishes a rule establishing an annual rate of inflation. This rate of inflation is used in computing the interest that is assessed when farm and agricultural or timber land, which are exempt from special benefit assessments, is withdrawn or removed from current use classification.

   1. (a) The rate of inflation is based on the implicit price deflator for personal consumption expenditures calculated by the United States Department of Commerce. This rate is used to calculate the rate of interest collected on exempt special benefit assessments.
   2. (b) The rate is published by December 31st of each year and applies to all withdrawals or removals from the farm and agricultural or timber land classifications that occur the following year.

3. (3) Assessment of rate of interest. An owner of classified farm and agricultural or timber land is liable for interest on the exempt special benefit assessment. Interest accrues from the date the local improvement district is created until the land is withdrawn or removed from classification. Interest accrues and is assessed in accordance with WAC 458-30-550.

   1. (a) Interest is assessed only for the time (years and months) the land remains classified under RCW 84.34.020 (2) or (3).
   2. (b) If the classified land is exempt from the special benefit assessment for more than one year, the annual inflation rates are used to calculate an average rate of interest. This average is determined by adding the inflation rate for each year the classified land was exempt from the special benefit assessment after the local improvement district was created. The sum of the inflation rates is then divided by the number of years involved to determine the applicable rate of interest.
   3. (c) Example. A local improvement district for a domestic water supply system was created in January 2010 and the owner used the statutory exemption provided in RCW 84.34.320. On July 1, 2017, the land was removed from the farm and agricultural classification. An average interest rate was calculated using the inflation rates for 2010 through 2017. The owner was then notified of the amount of previously exempt special benefit assessment, plus the average interest rate.

4. (4) Rates of inflation. The rates of inflation used to calculate the interest as required by WAC 458-30-550 are as follows:

   YEAR	PERCENT	YEAR	PERCENT
   1976	5.6	1977	6.5
   1978	7.6	1979	11.3
   1980	13.5	1981	10.3
   1982	6.2	1983	3.2
   1984	4.3	1985	3.5
   1986	1.9	1987	3.7
   1988	4.1	1989	4.8
   1990	5.4	1991	4.2
   1992	3.3	1993	2.7
   1994	2.2	1995	2.3
   1996	2.2	1997	2.1
   1998	0.85	1999	1.42
   2000	2.61	2001	1.89
   2002	1.16	2003	1.84
   2004	2.39	2005	2.54
   2006	3.42	2007	2.08
   2008	4.527	2009	-0.85 (negative)
   2010	1.539	2011	2.755
   2012	1.295	2013	1.314
   2014	1.591	2015	0.251
   2016	0.953	2017	1.553
   2018	2.169	2019	1.396
   2020	0.602	2021	3.860
   2022	6.457	2023	3.67
   2024	2.57	2025	2.44

[Statutory Authority: RCW 84.34.065, 84.34.141, 84.34.360, and 84.69.100. WSR 26-01-183, s 458-30-590, filed 12/23/25, effective 1/1/26; WSR 24-24-089, s 458-30-590, filed 12/3/24, effective 1/1/25; WSR 24-03-001, § 458-30-590, filed 1/3/24, effective 1/3/24; WSR 23-01-007, § 458-30-590, filed 12/7/22, effective 1/1/23; WSR 22-04-028, § 458-30-590, filed 1/24/22, effective 1/1/22; WSR 21-01-210, § 458-30-590, filed 12/23/20, effective 1/1/21; WSR 20-02-056, § 458-30-590, filed 12/24/19, effective 1/1/20; WSR 19-02-058, § 458-30-590, filed 12/27/18, effective 1/1/19; WSR 18-01-147, § 458-30-590, filed 12/20/17, effective 1/1/18; WSR 17-01-162, § 458-30-590, filed 12/21/16, effective 1/1/17; WSR 16-01-035, § 458-30-590, filed 12/9/15, effective 1/1/16; WSR 15-01-166, § 458-30-590, filed 12/23/14, effective 1/1/15; WSR 14-01-059, § 458-30-590, filed 12/13/13, effective 1/1/14; WSR 13-02-053, § 458-30-590, filed 12/26/12, effective 1/1/13; WSR 12-01-040, § 458-30-590, filed 12/13/11, effective 1/1/12. Statutory Authority: RCW 84.34.360. WSR 11-02-016, § 458-30-590, filed 12/29/10, effective 1/1/11; WSR 10-02-027, § 458-30-590, filed 12/29/09, effective 1/1/10; WSR 08-24-115, § 458-30-590, filed 12/3/08, effective 1/3/09; WSR 08-04-050, § 458-30-590, filed 1/31/08, effective 3/2/08. Statutory Authority: RCW 84.34.360 and 84.34.310. WSR 07-01-012, § 458-30-590, filed 12/7/06, effective 1/1/07; WSR 05-24-119, § 458-30-590, filed 12/7/05, effective 1/1/06; WSR 05-01-052, § 458-30-590, filed 12/7/04, effective 1/1/05; WSR 03-24-076, § 458-30-590, filed 12/2/03, effective 1/2/04; WSR 02-24-058, § 458-30-590, filed 12/3/02, effective 1/3/03; WSR 02-03-041, § 458-30-590, filed 1/8/02, effective 2/8/02; WSR 00-24-107, § 458-30-590, filed 12/6/00, effective 1/1/01; WSR 99-24-035, § 458-30-590, filed 11/23/99, effective 12/24/99; WSR 99-01-068, § 458-30-590, filed 12/14/98, effective 1/1/99; WSR 98-01-179, § 458-30-590, filed 12/23/97, effective 1/1/98; WSR 97-02-067, § 458-30-590, filed 12/31/96, effective 1/1/97; WSR 96-01-094, § 458-30-590, filed 12/19/95, effective 1/1/96; WSR 95-06-043, § 458-30-590, filed 2/24/95, effective 3/27/95. Statutory Authority: RCW 84.34.360. WSR 94-11-098, § 458-30-590, filed 5/17/94, effective 6/17/94; WSR 92-22-061, § 458-30-590, filed 10/29/92, effective 11/29/92. Statutory Authority: RCW 84.08.010 and 84.08.070. WSR 90-24-087, § 458-30-590, filed 12/5/90, effective 1/5/91. Statutory Authority: Chapter 84.34 RCW and RCW 84.34.360. WSR 89-05-010 (Order PT 89-3), § 458-30-590, filed 2/8/89. Statutory Authority: RCW 84.34.360. WSR 88-07-004 (Order PT 88-4), § 458-30-590, filed 3/3/88; WSR 87-07-009 (Order PT 87-3), § 458-30-590, filed 3/10/87.]