Pension vs. Lump Sum Calculator
1The Two Offers
2Assumptions
Breakdown
What Is a Pension vs. Lump Sum Calculator?
Companies winding down pension plans often hand retirees a choice: keep the promised monthly pension check, or take a one-time lump-sum buyout and invest it yourself. The two offers look incomparable — one is a stream, the other a pile. This calculator makes them comparable by converting the stream into a pile: it discounts every future pension check back to present value at the return you believe you could earn on your own, then puts that figure next to the lump sum and declares which is worth more in today’s dollars.
How It Works
A dollar arriving in 20 years is worth less than a dollar today, because today’s dollar could be invested and grow. Present value reverses that growth:
Present value of the pension, where PMT is the monthly check, i is the monthly discount rate (annual rate ÷ 12), and n is the number of expected payments:
PV = PMT × [1 − (1 + i)−n] ÷ iThe discount rate is the pivotal assumption. It represents the return you’d realistically earn investing the lump sum. Pick a high rate and future checks shrivel in today’s terms, flattering the lump sum; pick a low, conservative rate and the guaranteed stream shines. That’s why it’s worth running several rates rather than one.
Worked Example: $2,500 a Month vs. $400,000
Suppose your plan offers $2,500 a month or a $400,000 lump sum, and you expect payments for 25 years with a 5% discount rate. The 300 future checks total $750,000 in raw dollars, but discounted to today they’re worth about $427,650 — roughly $27,650 more than the buyout, so the pension wins. Now watch the assumptions swing the verdict: at a 7% discount rate the stream’s present value drops to about $353,717 and the lump sum wins by around $46,283. Expect only 15 years of checks at 5% and the stream is worth about $316,138 — again a lump-sum win.
Longevity Risk and the COLA Caveat
The “years of payments” box is really a bet on your lifespan. Live to 95 and a pension keeps paying long after the modeled horizon, making it far more valuable than the calculation shows; die early and the lump sum would have left money to heirs while many pensions simply stop (survivor options reduce the check in exchange for continuing it). Also check whether your pension carries a cost-of-living adjustment (COLA). This calculator assumes a level payment; a COLA pension is worth meaningfully more than the number shown here, while a level pension quietly loses buying power to inflation every year.
Common Mistakes to Avoid
Don’t compare the lump sum to the raw sum of checks ($750,000 above) — that ignores three decades of time value and wildly flatters the pension. Don’t use a stock-market-fantasy discount rate; a retiree actually spending the money can’t ride out crashes the way a young accumulator can. Don’t overlook survivor benefits, the plan’s backstops, or the tax treatment of a rollover versus a cash payout — taking a buyout as cash can trigger a painful tax bill. This calculator provides educational estimates only, not financial or tax advice; a pension election is usually irrevocable, so review it with a qualified professional first.
Frequently Asked Questions
What discount rate should I use?
A defensible starting point is the return of a conservative portfolio you would actually hold in retirement — often modeled in the 4–6% range — not the long-run stock average. Run 4%, 5%, and 7% and see whether the verdict flips; if it does, your decision hinges on investment risk you’d be taking on.
How many years of payments should I assume?
Base it on realistic life expectancy for your age and health, not a round number. Someone retiring at 65 might reasonably model 20–30 years. If a survivor option would keep paying a spouse, model the longer of the two lifetimes.
Does the calculator account for inflation or COLAs?
No — it values a level payment. If your pension has a cost-of-living adjustment, the stream is worth more than shown; if it doesn’t, remember that a fixed check loses purchasing power every year, which effectively strengthens the case for assets that can grow.
Is the lump sum taxable when I take it?
Taken as cash, a buyout is generally taxable income and may face withholding and penalties depending on age. Rolled directly into an IRA, tax is typically deferred until withdrawal. The mechanics matter enormously — talk to a tax professional before accepting any offer; this tool is educational only.