Updated October 30, 2026. Quick answer: MOSERS pays a Missouri state employee first hired on or after January 1, 2011, a plan called MSEP 2011, an annuity of 1.7% of final average pay for each year of credited service. Computed for 25 years and a $60,000 average, that is $25,500 a year (computed), or $2,125 a month (computed), at age 67. A member who retires at 55 or later with age and service totaling 90 takes the same formula, and one who retires at 62 to 66 without that loses half a percent for each month under 67. Enter your own numbers below; the figure is the life annuity, before any payment option.
Calculate your MSEP 2011 annuity
This page applies the annuity formula in the Revised Statutes of Missouri to your service, age and final average pay. It runs on this page and sends nothing anywhere. It covers a state employee for whom “each person who first becomes an employee on or after January 1, 2011, shall be a member of the year 2000 plan subject to the provisions of this section”, which MOSERS calls MSEP 2011. Enter your credited service from your MOSERS record, whole years and months, and the age you will be on your retirement date.
For a decision, use MOSERS itself: its member retirement pages, at mosers.org, cover the MSEP 2011 plan, and a MOSERS counselor can price a retirement date. This page is the published formula, shown so you can see the arithmetic.
The formula, as the statute prints it
Section 104.1024 says the annuity “shall be an amount for life equal to one and seven-tenths percent of the final average pay of the member multiplied by the member’s years of credited service”. Final average pay is defined in Section 104.1003 as “the average pay of a member for the thirty-six full consecutive months of service before termination of employment when the member’s pay was greatest”. The calculator asks for it as a yearly amount (12 times the monthly average). Credited service counts “a period expressed as whole years and any fraction of a year measured in twelfths”, which is why the calculator takes service in years and months.
The same section sets a floor: the annuity “shall not be less than a monthly amount equal to fifteen dollars multiplied by the member’s full years of credited service”. The calculator does not apply it, because it matters only to a very small annuity.
Worked example, calculated for 25 years of credited service and a $60,000 average: 1.7% x 25 = 42.5% of $60,000 = $25,500 a year (computed), $2,125 a month (computed).
Who can retire, and when the annuity is not reduced
Section 104.1091 sets the retirement dates for an employee hired in 2011 or later: “The member’s attainment of at least age sixty-seven and the completion of at least ten years of credited service; or the member’s attainment of at least age fifty-five with the sum of the member’s age and credited service equaling at least ninety”. The second test is the Rule of 90. The calculator adds age and service in months, so 54 years and 11 months plus 35 years does not count as 90, and it treats a member with fewer than 10 years as not yet eligible. The statute adds different tests for the highway patrol, the general assembly and statewide elected officials, which this page does not price.
These dates are for a person still employed or who left after becoming eligible. Section 104.1091 says “A vested former member’s normal retirement eligibility shall be based on the attainment of at least age sixty-seven and the completion of at least ten years of credited service.” and “A vested former member who terminated employment prior to the attainment of early retirement eligibility shall not be eligible for early retirement.”. Section 104.1024 treats “Any vested former member who terminated employment after attaining normal retirement eligibility” as a member. A person who left state employment before reaching the Rule of 90 or age 62 should not read the Rule of 90 or early-retirement results below as theirs; ask MOSERS.
A member who retires on the Rule of 90 before 62 also receives a second payment. Section 104.1024 says “the member shall receive a temporary annuity equal to eight-tenths of one percent of the member’s final average pay multiplied by the member’s years of credited service”, and Section 104.1091 says it “shall be payable if the member has attained at least age fifty-five with the sum of the member’s age and credited service equaling at least ninety”. It ends at “the member’s attainment of the earliest age of eligibility for reduced Social Security retirement benefits, but no later than age sixty-two”.
Worked example, calculated for 32 years and a $60,000 average, retiring at 58. Age 58 plus 32 years is 90, so the Rule of 90 is met. The life annuity is 1.7% x 32 = 54.4% = $32,640 a year (computed), $2,720 a month (computed). The temporary annuity is 0.8% x 32 = 25.6% = $15,360 a year (computed), $1,280 a month (computed), until 62.
Retiring at 62 to 66 without the Rule of 90: the reduction, computed
Section 104.1091 gives this member a path before 67: “shall be eligible for an early retirement annuity upon the attainment of at least age sixty-two and the completion of at least ten years of credited service”. Section 104.1033 sets the size of the cut: “The percent shall be one hundred percent reduced by one-half of one percent multiplied by the number of months by which age at early retirement is younger than normal retirement eligibility”. For a member who does not meet the Rule of 90, normal retirement eligibility is age 67, so the cut is half a percent for each month under 67.
Worked example, calculated for 20 years and a $60,000 average, retiring at 62. The annuity before reduction is $20,400 a year (computed). Age 62 is 60 months under 67, so the reduction is 60 x 0.5% = 30% and the annuity is $14,280 a year (computed), $1,190 a month (computed).
| Age at retirement | Months under 67 | Reduction | Annual annuity | Monthly annuity |
|---|---|---|---|---|
| 62 | 60 | 30% (computed) | $14,280 (computed) | $1,190 (computed) |
| 63 | 48 | 24% (computed) | $15,504 (computed) | $1,292 (computed) |
| 64 | 36 | 18% (computed) | $16,728 (computed) | $1,394 (computed) |
| 65 | 24 | 12% (computed) | $17,952 (computed) | $1,496 (computed) |
| 66 | 12 | 6% (computed) | $19,176 (computed) | $1,598 (computed) |
The table is for 20 years of service and a $60,000 average; the Rule of 90 is not met at any of these ages with that service.
What to do next
1. Get MOSERS’s own number. A MOSERS counselor can price a retirement date, and the estimate is the system’s figure; this page is the printed formula.
2. The rest of the MOSERS decisions. Payment options, the cost-of-living increase and buying service are on the Missouri MOSERS retirement decisions page, and the latest increase is on the MOSERS COLA page.
3. Tax. Missouri’s treatment of pension income is on the Missouri pension tax page. Federal tax applies too: “The taxable part of your pension or annuity payments is generally subject to federal income tax withholding.” The withholding form is described on the IRS page for Form W-4P: “so your payer can withhold the correct amount of federal income tax from your periodic pension, annuity”.
Where this calculator stops
It prices one slice of MOSERS: the MSEP 2011 plan for an employee first hired on or after January 1, 2011, in the general state employee class. Employees hired earlier are in MSEP 2000 or the closed plan, which use other ages and rules and are not modelled here. It leaves out the highway patrol, general assembly and statewide elected official rules, service not covered by Social Security (the statute adds a higher rate for that service), the $15 floor, payment options and survivor benefits, cost-of-living increases, purchased service and its cost (the pension buyback calculator covers purchases in general), and the limit the Internal Revenue Code places on pay and benefits. It reads age and service as you enter them. One reading to know: for a member who is not yet on the Rule of 90, the page counts the early-retirement cut from age 67, the other normal retirement test in the statute.
How it was checked: a second, independent engine (exact fractions, with the percentages, ages, points and reduction read from the archived statute text) agreed with this page’s engine on 300,000 random combinations of service, age and pay, and the shipped script was driven in a browser on a grid of cases against both. The rules were read from Sections 104.1003, 104.1021, 104.1024, 104.1033 and 104.1091 of the Revised Statutes of Missouri.
Common mistakes
- Using your final salary. The statute averages your 36 highest consecutive months of pay.
- Using a rate from memory. The statute prints 1.7% of final average pay for each year of credited service in this plan.
- Expecting the Rule of 90 to cut the age to 55 for everyone. It needs age and service to total 90, and the member must be at least 55.
- Forgetting the temporary annuity. A Rule of 90 retirement before 62 adds 0.8% of final average pay for each year, until 62.
- Using the Rule of 90 or early retirement after leaving state service early. A vested former member who left before becoming eligible waits for age 67 with 10 years.
Related: Missouri MOSERS retirement decisions, public pension decisions by system, single life versus joint and survivor, and Missouri retirement taxes.
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Answer againSources
- Missouri Revised Statutes, Section 104.1003 (definitions, year 2000 plan): https://revisor.mo.gov/main/OneSection.aspx (section page)
- Missouri Revised Statutes, Section 104.1021 (credited service): https://revisor.mo.gov/main/OneSection.aspx (section page)
- Missouri Revised Statutes, Section 104.1024 (retirement annuity amount): https://revisor.mo.gov/main/OneSection.aspx (section page)
- Missouri Revised Statutes, Section 104.1033 (early retirement annuity): https://revisor.mo.gov/main/OneSection.aspx (section page)
- Missouri Revised Statutes, Section 104.1091 (employees first hired on or after January 1, 2011): https://revisor.mo.gov/main/OneSection.aspx (section page)
- Missouri State Employees’ Retirement System (MOSERS), member retirement pages: https://mosers.org/members/retirement/
- IRS, Topic no. 410, Pensions and annuities: https://www.irs.gov/taxtopics/tc410
- IRS, About Form W-4P, Withholding Certificate for Pension or Annuity Payments: https://www.irs.gov/forms-pubs/about-form-w-4p
Read from the system publications linked above on October 30, 2026. General information, not legal or tax advice, and not an estimate from the retirement system. Your own facts decide the outcome, and your retirement system, your plan administrator or a benefits advisor is the right place to confirm anything consequential.