Idaho Code 59-1355 provides for an annual Cost of Living Adjustment (COLA) to be applied to the March retirement benefit. The COLA is tied to the change to the Consumer Price Index (CPI-U) for the twelve months ending the previous August. A COLA of greater than one percent is subject to legislative approval. Below is a history of previous COLAs:
Historical Numbers
| Dates | Rate |
| 03/01/2024 | 1.0% |
| 03/01/2023 | 1.0% |
| 03/01/2022 | 3.5% |
| 03/01/2021 | 1.0% |
| 03/01/2020 | 1.7% [a] |
| 03/01/2019 | 1.0% |
| 03/01/2018 | 1.9% |
| 03/01/2017 | 1.1% |
| 03/01/2016 | 0.2% [b] |
| 03/01/2015 | 1.7% [c] |
| 03/01/2014 | 1.0% |
| 03/01/2013 | 1.0% |
| 03/01/2012 | 1.0% |
| 03/01/2011 | 1.0% |
| 03/01/2010 | 2.48% [d] |
| 03/01/2010 | -1.48% [d] |
| 03/01/2009 | 1.0% |
| 03/01/2008 | 2.0% |
| 03/01/2007 | 3.8% |
| 03/01/2006 | 3.6% |
| 03/01/2005 | 2.7% [e] |
| 03/01/2004 | 2.2% |
| 03/01/2003 | 1.0% |
| 03/01/2002 | 2.7% |
| 03/01/2001 | 3.4% |
| 03/01/2000 | 2.3% |
| 03/01/1999 | 1.6% [f] |
| 03/01/1998 | 2.2% |
| 03/01/1997 | 2.9% |
| 03/01/1996 | 2.6% |
| 03/01/1995 | 2.9% |
| 03/01/1994 | 2.8% [g] |
| 03/01/1993 | 3.1% [h] |
| 03/01/1992 | 3.8% [i] |
| 03/01/1991 | 5.6% |
| 03/01/1990 | 4.7% |
| 03/01/1989 | 1.0% |
| 03/01/1988 | 1.0% |
| 03/01/1987 | 1.5% |
| 01/01/1986 | 1.0% |
| 01/01/1985 | 4.2% |
| 01/01/1984 | 2.9% |
| 01/01/1983 | 5.1% |
| 01/01/1982 | 6.0% |
| 01/01/1981 | 6.0% |
| 01/01/1980 | 6.0% |
| 01/01/1979 | 6.0% |
| 01/01/1978 | 6.0% |
| 01/01/1977 | 6.0% if last contributed prior to 01/01/1976; 1976 retiree 5.3% |
| 01/01/1976 | 3.0% |
| 01/01/1975 | 3.0% |
| 01/01/1974 | 3.0% |
| 01/01/1973 | 3.0% |
| 01/01/1972 | 3.0% |
| 01/01/1971 | 3.0% |
| 01/01/1970 | 3.0% |
| 07/01/1969 | Rates varied according to retirement date |
Note: Starting 01/01/1980 and to date, if the last contribution was in the prior year the COLA is apportioned to the number of months. See formulas.
[a] For 2020, the board also awarded a retro COLA (tied to 2011, 2012, 2013, and 2018 COLAs) to provide an additional increase of up to 4.8%, depending on the date of the last contribution for each retiree.
[b] For 2016, the board also awarded a retro COLA (tied to the 2012 COLA) to provide a net increase of 1.0%.
[c] For 2015, the board also awarded a retro COLA (tied to 2012, 2011, and 2009 COLAs) to provide an additional increase of up to 2.3% depending on the date of the last contribution for each retiree.
[d] The C.P.I. (Consumer Price Index) used for retirees 2010 COLA Calculation was a -1.48% resulting in a March 1st, 2010 COLA of -1.48%. Subsequently, to provide retirees with a net COLA of 1%, the board applied a retro-COLA of 2.48%.
[e] There was also a retro-COLA to bring all retirees whose date of the last contribution was before March 1, 2003, to 100% C.P.I. (Consumer Price Index) purchasing power.
[f] There was also a retro-COLA to bring all retirees who retired on or before January 31, 1989, to 100% C.P.I. (Consumer Price Index) purchasing power.
[g] There was also a retro-COLA to bring all retirees who retired on or before December 31, 1981, to a minimum of 90% C.P.I. (Consumer Price Index) purchasing power.
[h] There was also a retro-COLA to bring all retirees who retired in 1979 or before, up to a minimum of 80% C.P.I. (Consumer Price Index) purchasing power.
[i] There was also a retro-COLA to bring all retirees who retired in 1974 or before, up to a minimum of 70% C.P.I. (Consumer Price Index) purchasing power.