MPSERS Final Average Compensation Calculation: How FAC Determines Your Pension

Your Final Average Compensation is the single biggest variable in your MPSERS pension calculation. Get the FAC wrong — or misunderstand which pay items count — and every pension estimate you've run is off.

The Basic Formula

Every MPSERS defined benefit pension starts from the same equation:

Monthly Pension = (FAC × Years of Service × 1.5%) ÷ 12

FAC is your average compensation during your highest-earning consecutive months of service. Years of Service is your total credited service (one full year requires 1,020 hours in a school fiscal year). The 1.5% multiplier is standard across Basic, MIP, and Pension Plus tiers — though some MIP members who elected the reduced multiplier under PA 300 of 2012 may have 1.25% for post-2012 service.

36 Months vs 60 Months

Your plan tier determines which averaging window applies:

60 consecutive months (5 years): Basic Plan members. This longer window smooths out salary spikes but also means any single high-earning year has less impact on your FAC.

36 consecutive months (3 years): MIP, Pension Plus, and Pension Plus 2 members. The shorter window makes your final few years of earnings more influential — a promotion or lane change in your last three years has a larger effect on your pension than it would under a 5-year average.

The window must be consecutive months. ORS selects the highest-earning consecutive period automatically, but you should verify this in your miAccount estimates.

What Counts Toward FAC

Reportable compensation — the pay your employer reports to ORS as pensionable wages — includes your base salary, overtime, longevity pay, and certain stipends. The specifics depend on your employer's reporting practices and collective bargaining agreement.

What typically does not count: lump-sum sick leave buyouts paid at termination, severance payments, payments for unused vacation time, and non-cash benefits. These are excluded from FAC calculations even if they appear on your final paycheck.

Summer pay timing matters for members whose salary is spread over 12 months but whose work year is less than 12 months. The months your pay is reported in affect which consecutive months form your highest FAC window. If you're uncertain which months your employer reports your wages to ORS, ask your district's payroll office.

How a Small FAC Difference Compounds

Consider a member with 30 years of service. Every $1,000 increase in FAC produces an additional $375 in annual pension ($1,000 × 30 × 1.5%). Over a 25-year retirement, that's $9,375 — and MIP members with the 3% annual COLA see that gap widen each year.

This is why verifying your FAC before filing your application is worth the effort. Check your miAccount Member Statement for reportable compensation in each fiscal year. If a year looks low — perhaps you were on unpaid leave, or your employer misreported wages — contact ORS to investigate before you file.

Worked Example

A MIP member whose service uses the 1.5% multiplier, with 28 years of service and a highest 36-month average salary of $72,000:

• Annual pension: $72,000 × 28 × 1.5% = $30,240
• Monthly gross: $30,240 ÷ 12 = $2,520

That's the Straight Life amount before any survivor option reduction. The 3% annual COLA (for MIP members) adds $75.60 per month in the first year, compounding annually on the base amount.

A Basic Plan member with the same 28 years and the same salary averaged over 60 months might see a slightly different FAC due to the longer averaging window — especially if their salary increased sharply in the final two years.

Verifying Your FAC Before You File

Log into miAccount and run pension estimates across several potential retirement dates. Compare the FAC figure in each estimate. If working one additional year would push a lower-earning year out of your FAC window and replace it with a higher-earning one, the monthly pension increase may be substantial — or it may be marginal. Run the numbers both ways.

The MPSERS Retirement Guide includes a FAC verification worksheet and step-by-step instructions for reading your miAccount pension estimate, so you can confirm your numbers before making a permanent election.

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