Pension vs. Lump Sum Calculator

How the pension vs. lump sum comparison works

The central concept is present value: what is the pension's stream of future payments worth in today's dollars? To answer this, the calculator discounts each future payment back to the present using your assumed investment return rate. That rate is the key variable. A higher assumed rate makes the lump sum look better (because you expect to earn more by investing it); a lower rate makes the pension look better.

For a pension with no cost-of-living adjustment, the present value uses the standard annuity formula:

monthly payment = P
annual discount rate = r, monthly rate = r / 12
number of payments = n = years x 12

PV = P x (1 - (1 + r/12)^(-n)) / (r/12)

If the pension includes a cost-of-living adjustment (COLA rate g per year), a growing annuity formula is used instead, discounting each inflation-adjusted payment back to today.

For the lump sum, the monthly drawdown income uses the standard PMT formula: the level monthly payment that exactly depletes the lump sum over the chosen number of years at the assumed return.

monthly drawdown = L x (r/12) x (1 + r/12)^n / ((1 + r/12)^n - 1)

where L is the lump sum, r is the annual return, and n = years x 12.

Worked example with default values

Pension: $2,500/month, no COLA, 25 years, discount rate 5%.

1. Monthly rate r/12 = 0.05 / 12 = 0.004167
2. n = 25 x 12 = 300 payments
3. PV = 2,500 x (1 - (1.004167)^(-300)) / 0.004167 = approximately $426,124
4. Lump sum offer = $450,000. Lump sum exceeds PV by approximately $23,876, so the lump sum has a slight mathematical edge at 5%.
5. Monthly drawdown from $450,000 over 25 years at 5%: approximately $2,632/month.

Lowering the assumed return to 4% shifts the balance: the pension's PV rises to roughly $475,000, making it the more valuable option mathematically. This illustrates why the assumed return is the most important variable.

Break-even age: the key question

The break-even age is the age at which cumulative pension payments equal the original lump sum offer. Before that age, the lump sum holder is ahead; after it, the pension recipient has received more in total.

The calculator finds the break-even year iteratively: it tracks the cumulative pension received year by year and compares it to the lump sum. If break-even occurs before your estimated end-of-payments age, you would receive more from the pension in total, all else being equal. If it occurs after, the lump sum holder comes out ahead (in nominal terms) even without any investment return.

A simple break-even estimate (ignoring investment returns on either side) is just:

break-even years = lump sum / (monthly pension x 12)

For the defaults: $450,000 / ($2,500 x 12) = 15 years, meaning break-even at age 80. The calculator's figure accounts for the time value of money on both sides.

Life expectancy matters enormously. According to the SSA Actuarial Life Table, the average US life expectancy at age 65 is roughly 18-20 years (around age 83-85). If you expect to live significantly longer than break-even, the pension may be the better choice purely on total-payments received. If you have health concerns suggesting a shorter lifespan, the lump sum may make more sense.

Factors beyond the numbers

Survivor benefits. Many pensions offer joint-and-survivor options that continue payments (at a reduced amount) to a spouse after you die. A lump sum can also be left to heirs. If survivor income is important, compare the pension with survivor option to the lump sum.

Plan solvency and PBGC protection. The Pension Benefit Guaranty Corporation insures most private-sector defined benefit plans up to set limits. If your pension exceeds those limits or comes from a government plan (which is not PBGC-insured), the security of the annuity depends on the sponsoring entity. Government plans are generally backed by their taxing authority.

Investment risk. The lump sum comparison assumes you can earn the stated return consistently. In practice, returns vary and sequence-of-returns risk (poor early returns depleting the balance) can significantly reduce actual income. A pension eliminates that risk for the covered amount.

Taxes. Both pension income and lump sum drawdown income are typically taxed as ordinary income. A direct rollover of a pension lump sum to a traditional IRA defers tax until withdrawal. Roth conversion strategies may also apply. Consult a tax professional for your specific situation.

Other assets and income. If you have substantial other assets (401(k), Social Security, rental income), the guaranteed income from a pension may be less critical and the flexibility of a lump sum more valuable. If the pension would be your primary income, its certainty has additional value not captured in a present-value calculation.