Missouri MOSERS Retirement Calculator

The 1.6% vs 1.7% tier change

Missouri reduced the MOSERS benefit multiplier from 1.7% to 1.6% for employees who began service on or after January 1, 2018. That's a 5.9% reduction in the accrual rate. For a long-career member, it adds up.

Annual Benefit = 1.7% x Years of Service x FAS (members before January 1, 2018)
Annual Benefit = 1.6% x Years of Service x FAS (members on or after January 1, 2018)

A pre-2018 member with 30 years and a $60,000 FAS: 0.017 x 30 x $60,000 = $30,600 per year, $2,550 per month. The same person under the post-2018 formula: 0.016 x 30 x $60,000 = $28,800 per year, $2,400 per month. The difference is $1,800 annually, $54,000 over 30 years of retirement. Not trivial.

Pre-2018 members who are still working should be aware of this distinction when reviewing retirement projections from MOSERS. The tier you're in depends solely on your original hire date into MOSERS-covered employment, not on any election or enrollment choice.

The Rule of 80: how it actually works

MOSERS' Rule of 80 requires that age plus years of service equals or exceeds 80, with a minimum retirement age of 48. The age 48 floor is lower than Missouri's neighboring states (Kansas KPERS requires age 55 for an equivalent rule), though reaching 80 at 48 requires 32 years of MOSERS service, which means starting at 16. In practice, the Rule of 80 is most commonly hit between ages 55 and 62.

A few worked examples show how the rule operates. Age 50 plus 30 years equals 80 exactly, eligible. Age 55 plus 25 years equals 80, eligible. Age 60 plus 20 years equals 80, eligible. Age 48 plus 32 years equals 80, eligible at the floor. In each case, the member can retire with a full unreduced benefit.

The Rule of 80 is more accessible than Iowa IPERS' Rule of 88 and Missouri's own teacher system (PSRS uses Rule of 80 as well). It's one of the more member-friendly features of the MOSERS benefit structure. A state employee who started at 25 reaches the Rule of 80 at 57.5 years old with 32.5 years of service (25 + 32.5 = 57.5, and 57.5 + 32.5 = 90, wait, let me recheck: to hit 80 starting at 25 you need age 52.5 with 27.5 years, since 52.5 + 27.5 = 80). Someone starting at 25 actually hits the Rule of 80 at around age 52 with 28 years.

That's 13 years before the standard age-65 path. At $2,400 per month, 13 extra years is $374,400 in additional lifetime benefits before any COLA adjustments.

The BackDROP: what it is and when it makes sense

BackDROP is one of the most distinctive features in any state pension system. It stands for Benefit Accrual for Deferred Retirement Option Plan, and it works like this: if you're already eligible to retire but you keep working anyway, you can elect BackDROP at actual retirement. MOSERS calculates what your monthly pension would have been starting from the BackDROP start date (up to 5 years back), accumulates those hypothetical monthly payments, and hands you that total as a lump sum. Your ongoing monthly benefit is then calculated as of the BackDROP start date, not your actual retirement date, which means it's lower than if you'd just kept accruing normally.

Concrete example: a member becomes eligible at age 55 under the Rule of 80 but keeps working until 60. If they elect a 5-year BackDROP, MOSERS calculates the monthly benefit they'd have had at 55, multiplies it by 60 months, and pays that as a lump sum. Say that was $2,200 per month at age 55. The lump sum is $2,200 x 60 = $132,000. But the ongoing monthly benefit from age 60 forward is $2,200 (the age-55 amount), not the higher benefit they'd have earned with 5 more years of service.

Whether BackDROP makes sense depends on several factors. If you would have retired at 55 but kept working partly out of habit or health insurance needs, and you can invest the $132,000 lump sum well, BackDROP might beat simple accrual. If you stayed to accrue 5 more years of service, normal accrual generally wins because those additional service years increase the monthly benefit for the rest of your life. MOSERS provides members with BackDROP projections, and comparing them to the non-BackDROP benefit is worth doing carefully with an advisor before deciding.

The lump sum can be rolled into an IRA or other qualified account to defer taxes, which is an important planning consideration. Taking it as cash triggers immediate income tax.

MOSERS vs PEERS: which system are you in?

Missouri has three public pension systems that often get confused. MOSERS covers general state employees. PEERS covers school support staff (custodians, bus drivers, food service workers, paraprofessionals). PSRS covers certified teachers and certain administrators.

If you work for a state agency, a state university as a classified employee, the Missouri Department of Corrections, or a similar state government position, you're in MOSERS. If you work in a public school in a non-certified role, you're in PEERS. Teachers are in PSRS.

PEERS uses a similar formula structure to MOSERS and has its own version of the Rule of 80. If you've worked in both systems at different points in your career, you may have service credit in more than one system. The systems don't generally combine service for eligibility purposes, so you'd need to check your specific situation with each.

Contribution rates and Social Security

MOSERS members contribute a percentage of their salary toward the pension, with the exact rate depending on when they were hired. The employer also makes contributions, though MOSERS is state-funded and the employer is essentially the state government.

Missouri MOSERS members generally participate in Social Security. Both employees and employers pay Social Security taxes, meaning MOSERS members build two income streams: the pension and Social Security. This contrasts with systems like Nevada PERS or Ohio STRS where members are typically excluded from Social Security.

The Social Security component matters most for members who retire under the Rule of 80 in their mid-50s. They'll collect MOSERS immediately but won't access Social Security until 62 at the earliest (reduced benefits) or 67 for full benefits. Planning the gap between MOSERS-only income and eventual Social Security income is a common focus for pre-retirees.

How MOSERS compares to neighboring states

Kansas KPERS uses a 1.85% multiplier for post-2015 members, higher than MOSERS' 1.6%. Illinois SERS uses a 1.67% multiplier. Iowa IPERS uses 2%. Arkansas APERS uses 2.15%. Missouri's 1.6% post-2018 rate is on the lower end for the Midwest.

Where MOSERS stands out is the Rule of 80 with a 48 minimum age and the BackDROP feature. No neighboring state pension offers BackDROP, and very few have an equivalent that's as accessible for mid-career employees. A Missouri state employee with 28 years of service at 52 has retirement options that a Kansas employee with identical circumstances doesn't.