Why the Definition of Pensionable Pay Matters
A pension formula may multiply credited service by a percentage of salary, but “salary” is not necessarily total compensation, the amount shown on a tax form, or the member’s most recent paycheck. The governing plan defines which pay counts, how it is averaged, whether a cap applies, and the date or period used to measure it. A small misreading of any one of these rules can change the pensionable salary used in the benefit calculation.
This tutorial focuses on translating those plan rules into a salary amount. The pension formula itself is assumed to be specified separately. The definitions and calculations here are aligned with the SOA Exam ALTAM (Advanced Long-Term Actuarial Mathematics) syllabus.
Start with Eligible and Excluded Pay
The first task is to classify each pay component using the plan wording. Base salary might be included while overtime, commissions, bonuses, expense reimbursements, or certain allowances are excluded. In another plan, one or more of those components might be included. The name of a pay item does not determine its treatment; the plan definition does.
A useful calculation sequence is to list each component, mark it as included or excluded, then total only eligible amounts for the relevant period. Do not add excluded pay and try to remove it later unless that is simply a convenient way to verify the arithmetic. In particular, a bonus paid during the averaging period is not automatically pensionable merely because it appears on a payroll record for that period.
Worked Example: Excluded Pay and an Annual Salary Cap
A hypothetical plan defines pensionable salary as base salary plus a fixed responsibility allowance. It excludes bonuses and overtime. The plan averages the pensionable salary for the three complete calendar years immediately before retirement and caps each year’s pensionable salary at $100,000. A member retires on January 1, 2025. The annual amounts are:
| Calendar year | Base salary | Fixed allowance | Bonus and overtime |
|---|---|---|---|
| 2022 | $90,000 | $4,000 | $11,000 |
| 2023 | $96,000 | $4,000 | $13,000 |
| 2024 | $102,000 | $4,000 | $15,000 |
Method. Identify eligible components for each year, apply the cap to each year, then average the three capped amounts. The three complete years before retirement are 2022, 2023, and 2024.
For 2022, eligible pay is $90,000 + $4,000 = $94,000. The bonus and overtime are excluded, so the capped amount remains $94,000.
For 2023, eligible pay is $96,000 + $4,000 = $100,000. The capped amount is $100,000.
For 2024, eligible pay is $102,000 + $4,000 = $106,000. Applying the annual cap gives $100,000.
The result is $98,000. A check is that the average is between the lowest and highest capped annual amounts, $94,000 and $100,000. A common mistake would be to include the bonuses and overtime because they were paid during the relevant years; that would contradict the stated plan definition.
Averaging Periods and the Order of Operations
Plans can use a specified number of years immediately before retirement, a fixed set of completed years, or the highest average over a stated number of consecutive years within a longer window. The chosen period is part of the definition, not a matter of preference. “Highest three-year average in the last five years,” for example, means compare the eligible consecutive three-year periods permitted by those five years, rather than selecting any three individual years.
A salary cap also has a defined place in the calculation. A plan may cap each year’s salary before averaging, or it may cap the resulting average. These rules can produce different amounts. Do not assume the two methods are equivalent.
Worked Example: Highest Consecutive Average with a Cap on the Average
A hypothetical plan uses the highest average of any three consecutive complete calendar years among the five years before retirement. It defines the annual salary amounts below as pensionable before applying a cap. The plan caps the resulting three-year average at $100,000. A member retires on January 1, 2026.
| Calendar year | Pensionable salary before cap |
|---|---|
| 2021 | $84,000 |
| 2022 | $90,000 |
| 2023 | $96,000 |
| 2024 | $102,000 |
| 2025 | $108,000 |
Method. Calculate each permitted three-year consecutive average, select the highest, and then apply the cap to that average. The three candidate periods are 2021–2023, 2022–2024, and 2023–2025.
The first average is \((84,000+90,000+96,000)/3=270,000/3=\$90,000\). The second is \((90,000+96,000+102,000)/3=288,000/3=\$96,000\). The third is \((96,000+102,000+108,000)/3=306,000/3=\$102,000\). Therefore, the highest uncapped average is $102,000.
The check is that $100,000 does not exceed the stated average-salary cap. A common error is to cap each annual amount at $100,000 before averaging. That would give \((84,000+90,000+96,000+100,000+100,000)\) as capped annual amounts, and the highest consecutive three-year average would be \((96,000+100,000+100,000)/3=\$98,666.67\). That is not the plan rule in this example: the cap applies after the highest average is found.
Measurement Dates and Partial Periods
A plan may measure salary at a specific date, over a period immediately before a date, or over completed calendar or plan years. These choices answer different questions. A “salary at the measurement date” may refer to the rate effective on that date; an “average over the preceding 36 months” usually calls for eligible pay earned throughout those months, subject to the plan’s exact wording.
Pay dates and periods of service are also distinct. A payment received during an averaging window might relate to work outside it, while a salary increase effective during the window can affect only the pay earned after its effective date if the plan uses earnings over time. Follow the plan’s specified basis—such as pay earned, pay paid, or rate in force—rather than substituting one for another.
Worked Example: A 36-Month Average Based on Pay Earned
A hypothetical plan measures pensionable salary as the annualized average of eligible pay earned during the 36 months immediately before retirement on October 1, 2025. Base salary and a shift allowance are eligible; a bonus is excluded. The member’s salary is $72,000 per year from October 1, 2022 through September 30, 2024, then $84,000 per year from October 1, 2024 through September 30, 2025. An eligible shift allowance of $600 per month is earned from April through September 2025. A $12,000 bonus is paid in September 2025.
Method. Divide the 36 months according to the applicable rates, total eligible pay earned in those months, exclude the bonus, and annualize the total over three years.
The first 24 months produce \(24\times(\$72,000/12)=24\times\$6,000=\$144,000\). The next six months, October 2024 through March 2025, produce \(6\times(\$84,000/12)=6\times\$7,000=\$42,000\). The final six months produce base pay of \(6\times\$7,000=\$42,000\), plus shift allowance of \(6\times\$600=\$3,600\), for $45,600.
The annualized average is $77,200. The check is that total eligible earnings over three years equal \(3\times\$77,200=\$231,600\). The September bonus is excluded even though it was paid within the measurement period. A common mistake is to include it based only on its payment date, or to treat the $84,000 rate as applying to all 36 months.
Why the Averaging Formula Works
For equal-length periods, an average is the total eligible amount divided by the number of periods. If a plan asks for an annualized average over \(m\) months, first find the average eligible pay per month, \(E/m\), then express that monthly average as an annual amount by multiplying by 12. This gives:
The derivation depends on equal weighting of the months and on the plan defining salary as an annualized average of pay earned. If the plan instead uses a rate in force on a date, or weights periods differently, this formula does not describe that rule. Likewise, a yearly average should not be substituted for a monthly average if the plan specifies a different measurement basis.
A Practical Rule-Reading Sequence
A disciplined sequence helps prevent an attractive but incorrect calculation. Record the measurement date first, because it determines which periods can be considered. Then identify the averaging window and whether it uses complete years or a rolling period. Classify eligible and excluded components before summing. Finally, apply annualization and caps in the order stated.
Identify the retirement, termination, valuation, or other date specified by the plan.
Determine whether the definition uses a point-in-time rate, completed years, or a period immediately before the date.
Include only amounts the plan defines as pensionable, and respect whether it refers to pay earned or paid.
Annualize or select the highest permitted consecutive period only when required.
Distinguish a cap on each year’s pay from a cap on the resulting average.
Common Mistakes
- Treating all compensation as pensionable. A bonus, overtime payment, or allowance is included only if the plan’s definition includes it.
- Choosing convenient years instead of permitted years. A highest-average rule generally restricts the candidate periods to consecutive years within a stated window.
- Applying a cap at the wrong stage. Capping each annual amount and capping an average are different operations.
- Confusing a pay date with the measurement basis. The plan may measure pay earned, pay paid, or a rate effective on a specified date.
- Annualizing when the plan does not call for it. Annualization is a definition-driven adjustment, not an automatic treatment of partial periods.
Pensionable salary is a plan-defined input, not a universal synonym for salary. For exam calculations, write the definition in operational terms before substituting numbers: which pay counts, which dates and periods apply, how the average is selected, and where any cap is imposed.
Check Your Understanding
Apply the stated plan rule in each original problem. Treat all salary amounts as annual unless otherwise stated.
- A plan includes base salary of $78,000 and excludes a $5,000 bonus. It averages the same defined salary over three complete years, with no cap. What pensionable salary results? (Answer: $78,000)
- A plan averages three complete years and caps each year before averaging at $100,000. Eligible salaries are $88,000, $104,000, and $112,000. What is the pensionable salary? (Answer: $96,000)
- A plan uses the highest average of two consecutive years from four years with pensionable salaries of $70,000, $82,000, $94,000, and $90,000. What is the pensionable salary? (Answer: $92,000)
- A plan annualizes eligible pay earned in the 18 months before the measurement date. The first 12 months have an annual salary rate of $60,000. For the next six months, the annual salary rate is $72,000 and an eligible allowance of $300 per month is earned. What is the annualized average? (Answer: $65,200)
- A plan selects the highest average of three consecutive years, then caps that average at $95,000. The available consecutive three-year period has eligible salaries of $80,000, $100,000, and $120,000. What is the pensionable salary? (Answer: $95,000)