Updated October 30, 2026. Quick answer: The Missouri Department of Transportation and Highway Patrol Employees’ Retirement System (MPERS) sets its COLA at 80% of the percentage increase in the CPI-U, with a maximum of 5% a year. The 2026 rate, announced January 16, 2026, is 2.152%. Closed Plan members hired before August 28, 1997 get not less than 4% nor more than 5% until total increases reach 65% of the initial benefit. The 2027 COLA is not published.
The formula
The MPERS COLA page says: “Regardless of which plan you are in, the annual COLA rate is based on 80% of the percentage increase in the Consumer Price Index for all Urban Consumers (CPI-U) for the United States, with an annual maximum of five percent.”
The Closed Plan floor
The page adds for the older Closed Plan group: “your annual COLA rate will not be less than four percent or more than five percent until the total increase equals 65% of your initial benefit.” After that cap it says: “After reaching this cap, your annual COLA rate will equal 80% of the increase in the CPI-U, with an annual maximum of five percent.”
When it is applied
The page says: “COLA increases are applied to your benefits in October each year for Closed Plan benefit recipients.” “COLA increases are received on the anniversary date of your retirement or BackDROP date for Year 2000 Plan benefit recipients.” “Members of the 2011 Tier who retire from a terminated-vested member status will receive their first COLA increase on the second anniversary date of their retirement.”
The 2026 rate
The MPERS release says: “MPERS is pleased to announce that the 2026 Cost-of-Living Adjustment (COLA) rate has been set at 2.152% .” As computed from the figures on the release, the annual average CPI-U for 2025, 321.943, over 313.509 for 2024 is an increase of 2.690%, and 80% of 2.690% is 2.152%.
The statute
The Missouri statute on annual benefit increases says: “any increase in the consumer price index shall be determined in January of each year”. The statute text does not name MPERS, so the link to the plan rests on the MPERS page.
What the documents do not say
The 2011 Tier rule comes from the MPERS page alone, because that statute text is not archived. The Closed Plan column of the rate history table is ambiguous in its header, so this page reads the 4% as the pre-August 28, 1997 hire rate under the 65% cap.
Where 2027 stands
The 2027 MPERS COLA is not published: the statute says the CPI increase is determined in January, so the rate is expected in January 2027.
Common mistakes
- Expecting the full CPI-U increase. The rate is 80% of it, capped at 5%.
- Assuming every plan gets the same date. Closed Plan benefits are adjusted in October; Year 2000 Plan benefits on the retirement or BackDROP anniversary; 2011 Tier benefits on the retirement anniversary (the second anniversary for terminated-vested retirees).
- Applying the 2026 rate to a Closed Plan member under the 65% cap. That group follows the 4% to 5% rule.
Related: Missouri MPERS retirement decisions, how public pension decisions work, and whether Missouri taxes pensions.
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Answer againSources
- MPERS, Cost-of-Living Adjustments (COLAs): www.mpers.org
- MPERS, 2026 Cost-of-Living Adjustment (COLA): www.mpers.org
- Missouri Revisor of Statutes, RSMo 104.415 Annual benefit increase: revisor.mo.gov
- Related official page (not quoted): IRS Tax Topic 410, Pensions and annuities: www.irs.gov
- Related official page (not quoted): IRS Tax Topic 411, Pensions: the General Rule and the Simplified Method: www.irs.gov
Read from the primary documents linked above on October 30, 2026. General information, not tax advice. Your own facts decide the outcome, and a preparer or the IRS itself is the right place to confirm anything consequential.