As a defined benefit plan, employer and employee contributions are required for all employees that are PERSI eligible. Employer contributions are immediately invested and are not available to members.
Historical Numbers
| Effective Date | General Member | Public Safety Member | School Employee Member | |||
| Employee | Employer | Employee | Employer | Employee | Employer | |
| 7/1/2024 | 7.18% | 11.96% | 10.83% | 14.65% | 8.08% | 13.48% |
| 7/1/2023 | 6.71% | 11.18% | 9.83% | 13.26% | 7.62% | 12.69% |
| 7/1/2022 | 7.16% | 11.94% | 9.13% | 12.28% | 7.16% | 11.94% |
| 7/1/2021 | 7.16% | 11.94% | 9.13% | 12.28% | ||
| 7/1/2019 | 7.16% | 11.94% | 8.81% | 12.28% | ||
| 7/1/2013 | 6.79% | 11.32% | 8.36% | 11.66% | ||
| 3/1/2010 | 6.23% | 10.39% | 7.69% | 10.73% | ||
| 7/1/2004 | 6.23% | 10.39% | 7.65% | 10.73% | ||
| 7/1/2003 | 5.86% | 9.77% | 7.21% | 10.11% | ||
| 11/1/1997 | 5.86% | 9.77% | 7.21% | 10.01% | ||
| 10/1/1994 | 6.97% | 11.61% | 8.53% | 11.85% | ||
| 10/1/1993 | 6.38% | 10.63% | 7.82% | 10.87% | ||
| 7/1/1993 | 5.84% | 9.75% | 7.19% | 9.99% | ||
| 10/1/1992 | 5.84% | 9.75% | 7.02% | 9.75% | ||
| 10/1/1985 | 5.34% | 8.89% | 6.40% | 8.89% | ||
| 10/1/1984 | 5.30% | 8.82% | 6.35% | 8.82% | ||
| 10/1/1983 | 5.26% | 8.75% | 6.30% | 8.75% | ||
| 7/1/1983 | 5.22% | 8.75% | 6.25% | 8.75% | ||
| 3/1/1983 | 5.22% | 8.75% | 6.05% | 8.75% | ||
| 10/1/1982 | 5.05% | 9.05% | 6.05% | 9.05% | ||
| 7/1/1982 | 5.01% | 9.50% | 6.00% | 9.50% | ||
| 7/1/1981 | 4.84% | 9.50% | 5.80% | 9.50% | ||
| 7/1/1980 | 4.67% | 9.50% | 5.60% | 9.50% | ||
| 7/1/1979 | 4.50% | 8.50% | 5.40% | 8.50% | ||
| 7/1/1977 | 4.50% | 7.30% | 5.40% | 7.30% | ||
| 7/1/1974 | 4.50% | 7.00% | 5.40% | 7.00% | ||
| 7/1/1971 | 3.00% | 7.00% | 3.60% | 7.00% | ||
| 1/1/1968 | 3.00% | 7.51% | 3.60% | 7.51% | ||
| 7/1/1967 | 3.00% | 8.00% | 3.60% | 8.00% | ||
| 1/1/1967 | 3.00% | 8.10% | 3.60% | 8.10% | ||
| 7/1/1965 | 3.00% | 9.10% | 3.60% | 9.10% |
Interest accrues to member accounts monthly according to the formula provided in IDAPA 59.01.03.200.
Historical Numbers
Members are paid interest on their PERSI account balances at a rate that is determined annually by a formula established in PERSI rules. By rule, regular interest for each calendar year is the greater of 90% of the rate of return on the PERSI fund net of all expenses for the fiscal year ending immediately prior to the calendar year as reported in the actuary’s annual valuation report, or 1%.
The rate for each calendar year is based on the annual net rate of return at the end of the previous fiscal year (June 30). The interest rate will change January 1 of each year based on investment performance for the fiscal year ending the previous June 30.
| Dates | Annual Interest Rate Compound Monthly |
| 01/01/2024 to 12/31/2024 | 8.20% |
| 01/01/2023 to 12/31/2023 | 1.00% |
| 01/01/2022 to 12/31/2022 | 24.69% |
| 01/01/2021 to 12/31/2021 | 2.39% |
| 01/01/2020 to 12/31/2020 | 7.22% |
| 01/01/2019 to 12/31/2019 | 7.57% |
| 01/01/2018 to 12/31/2018 | 11.03% |
| 01/01/2017 to 12/31/2017 | 1.29% |
| 01/01/2016 to 12/31/2016 | 2.39% |
| 01/01/2015 to 12/31/2015 | 15.04% |
| 01/01/2014 to 12/31/2014 | 7.77% |
| 01/01/2013 to 12/31/2013 | 1.04% |
| 01/01/2012 to 12/31/2012 | 18.16% |
| 01/01/2011 to 12/31/2011 | 10.74% |
| 01/01/2010 to 12/31/2010 | 1.00% |
| 01/01/2009 to 12/31/2009 | 1.00% |
| 07/01/2008 to 12/31/2008 [a] | 17.51% |
| 01/01/2008 to 06/30/2008 [a] | 19.46% |
| 01/01/2007 to 12/31/2007 | 11.69% |
| 01/01/2006 to 12/31/2006 | 10.24% |
| 01/01/2005 to 12/31/2005 | 17.51% |
| 01/01/2004 to 12/31/2004 | 3.22% |
| 01/01/2003 to 12/31/2003 | 1.90% (Treasury Bill Rate) |
| 01/01/2002 to 12/31/2002 | 4.82% |
| 01/01/2001 to 12/31/2001 | 12.86% |
| 01/01/2000 to 12/31/2000 | 11.11% [b] |
| 01/01/1999 to 12/31/1999 | 4.75% |
| 07/01/1998 to 12/31/1998 | 5.25% |
| 07/01/1997 to 06/30/1998 | 5.50% |
| 01/01/1997 to 06/30/1997 | 5.25% |
| 07/01/1996 to 12/31/1996 | 5.00% |
| 01/01/1996 to 06/30/1996 | 5.50% |
| 07/01/1995 to 12/31/1995 | 6.00% |
| 01/01/1995 to 06/30/1995 | 5.25% |
| 07/01/1994 to 12/31/1994 | 4.25% |
| 01/01/1993 to 06/30/1994 | 4.00% |
| 07/01/1992 to 12/31/1992 | 4.50% |
| 01/01/1992 to 06/30/1992 | 5.00% |
| 07/01/1991 to 12/31/1991 | 6.50% |
| 01/01/1991 to 06/30/1991 | 7.25% |
| 07/01/1990 to 12/31/1990 | 7.50% |
| 07/01/1989 to 06/30/1990 | 7.00% |
| 07/01/1987 to 06/30/1989 | 6.50% |
| 07/01/1986 to 06/30/1987 | 7.50% |
| 07/01/1984 to 06/30/1986 | 9.00% |
| 07/01/1983 to 06/30/1984 | 8.50% |
| 07/01/1982 to 06/30/1983 | 8.00% |
| 07/01/1981 to 06/30/1982 | 7.50% |
| 07/01/1980 to 06/30/1981 | 7.00% |
| 07/01/1976 to 06/30/1980 | 6.50% |
| 07/01/1973 to 06/30/1976 | 6.00% |
| 07/01/1972 to 06/30/1973 | 5.50% |
| 01/01/1970 to 06/30/1972 | 5.00% |
| 01/01/1969 to 12/31/1969 | 4.50% |
| 07/01/1968 to 12/31/1968 | 4.25% |
| 07/01/1967 to 07/01/1968 | 4.00% |
[a] In the October 2007 PERSI board meeting, the board adopted a rule change that altered the formula for setting the interest rate. The 2008 legislature approved the change and it became effective July 1, 2008.
Rule 59.01.07.100 now states:
Regular interest for each calendar year shall be the greater of ninety percent (90%) of the rate of return on the PERSI fund net of all expenses for the fiscal year ending immediately prior to the calendar year as reported in the actuary’s annual valuation report or one percent (1%).
On July 1, 2008, the regular interest rate was changed from 19.46% to 17.51% in accordance with this rule change.
Prior to 2008…
The regular interest rate was the greater of:
1. The rate of return on the PERSI fund net of all expenses for the fiscal year ending immediately prior to the calendar year as reported in the actuary’s annual valuation report, or 2. The average interest rate of 13-week US Treasury bills on the last business day of each calendar quarter of the fiscal year ending immediately prior to the calendar year as reported in the “Money Rate” section of the Wall Street Journal.
[b] Prior to 1999…
The regular interest rate was based on the rate paid by local banks on one and two-year certificates of deposits with a $5,000 minimum balance.