Updated October 21, 2026. Quick answer: The Montana PERS handbook says the Guaranteed Annual Benefit Adjustment (GABA) increases a retirement benefit every year for an eligible member who has received the benefit for at least 12 months, with the first increase the following January. The rate depends on the hire date: 3% for members hired before July 1, 2007, 1.5% for those hired from July 1, 2007 through June 30, 2013, and a variable rate from 0% to 1.5% for those hired on or after July 1, 2013.
The statute words the middle group with a carve-out. Section 19-3-1605(4)(b) sets 1.5% “if the member was hired or assumed office on or after July 1, 2007, and before June 30, 2013, and the benefit recipient is not otherwise covered under subsection (4)(a)(ii)”. Subsection (4)(a)(ii) covers a member in a retirement system provided for in Title 19 “and the guaranteed annual benefit adjustment provision for that member under that system is a 3% benefit increase”.
What this covers
The handbook’s Benefit Increases section begins “The Guaranteed Annual Benefit Adjustment (GABA) will increase your retirement benefit every year if you are eligible.” Its glossary defines GABA as “A benefit increase based on an annual actuarial valuation of the PERS trust fund, provided to offset inflation.” This page follows those passages. The wider set of choices is on Montana PERS retirement decisions and public pension retirement decisions.
Who is eligible and when it starts
The handbook says “You need to have received your benefit for at least 12 months to become eligible for a GABA increase.” “You will receive your first increase in your retirement benefit payment that following January.”
The rate by hire date
The handbook lists “The percentage of increase for PERS members hired:” Each row below is the handbook’s line, set out as a table.
| Hired | Percentage of increase |
|---|---|
| Before July 1, 2007 | 3% |
| Between July 1, 2007, and June 30, 2013 | 1.5% |
| On or after July 1, 2013 | variable ranging from 0% to 1.5% |
What GABA applies to
The handbook says GABA applies to these benefits, each quoted.
| Benefit | What the handbook says |
|---|---|
| Service retirement | “Service Retirement Benefits” |
| Early retirement | “Early Retirement Benefits” |
| Disability retirement | “Disability Retirement Benefits” |
| Survivors | “Survivorship Benefits” |
It also says “GABA also applies to recipients other than members, such as contingent annuitants and survivors, and does not apply to a person receiving the lump-sum death payment as an annuity.”
Where GABA does not apply
On the death benefit the handbook says “Increases (such as GABA) that may apply to other monthly benefits will not apply to monthly annuity payments.” “Benefit increases such as the GABA which do not apply to death annuity payments, do apply to the survivorship benefit.”
For a retiree who returns to full-time work, it says “guaranteed annual benefit adjustment (GABA) increases will not accrue on your suspended retirement benefits when your return to full-time employment.”
A worked illustration, not a handbook example
Take an invented member hired between July 1, 2007 and June 30, 2013, so the handbook’s rate is 1.5%, with an invented monthly benefit of $1,000 (invented, for the computation). One increase is 1,000 x 1.5% = 15, so the monthly benefit after the first increase is 1,000 + 15 = 1,015. These inputs are invented to show the arithmetic. For a member hired on or after July 1, 2013 the rate is variable from 0% to 1.5%, so the handbook gives no fixed percentage to apply, and your own rate is whatever MPERA reports for the year.
What to do and where to look
The rate for a given year is not fixed in the handbook for members hired on or after July 1, 2013, so MPERA is the place to confirm it. For the federal equivalent see the CSRS and FERS cost-of-living adjustment for 2027. The tax treatment of the pension is on whether Montana taxes pensions.
Edition
This page reads Montana Public Employee Retirement Administration (MPERA), Public Employees’ Retirement System (PERS) Member Handbook, the current file MPERA served on 2026-10-21. Check the edition, your hire date and your own membership record with MPERA; the handbook’s text controls over this summary.
Common mistakes
- Expecting a GABA the first year. The handbook says “You need to have received your benefit for at least 12 months to become eligible for a GABA increase.”
- Expecting GABA on a fixed monthly death annuity. The handbook says “The amount of the monthly payment will not change.”
- Assuming one rate for every member. The handbook gives three rates, by hire date, and the newest group’s rate is “variable ranging from 0% to 1.5%”
Related: Montana PERS retirement decisions, the CSRS and FERS cost-of-living adjustment for 2027, public pension retirement decisions, and whether Montana taxes pensions.
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Answer againSources
- Montana Public Employee Retirement Administration (MPERA), Public Employees’ Retirement System (PERS) Member Handbook: mpera.mt.gov
- Related official page (not quoted): Montana Public Employee Retirement Administration home page: mpera.mt.gov
Read from the pension system handbooks linked above on October 21, 2026. General information, not tax advice. Your own facts decide the outcome, and a pension system or a qualified professional is the right place to confirm anything consequential.