Updated: August 17, 2026
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Pension plans that offer a lump-sum option are asking you to make one of the largest financial trades of your life. The check looks big. The math behind whether it is fair to you sits inside a single number: the implied internal rate of return.
This page walks through that number and the guardrails around it, without any product pitch. It covers the discount-rate math, a worked example at typical retirement figures, spousal survivor rules, PBGC backing, tax treatment, sequence-of-returns risk on an invested lump sum, and the ERISA disclosure your plan owes you before you sign.
What the decision actually is
Your plan offers two paths from the same accrued benefit. Path A is a single lump-sum cashout you take today. Path B is a stream of monthly checks for the rest of your life, and, if you elect it, part of your spouse’s life.
The plan has derived the lump sum from the same actuarial factors that produce the annuity. The two paths are supposed to be economically equivalent to the plan at its assumed discount rate. Whether they are equivalent to you depends on inputs the plan does not know: how long you will live, how you would invest a cash payout, and what tax bracket you occupy.
How to compute the implied IRR of the lump-sum offer
The implied IRR is the annual discount rate that makes the present value of the promised annuity stream equal to the lump-sum offer. Any online present-value-of-an-annuity calculator can back it out. The level-payment formula is: PV equals PMT times (1 minus (1 plus r) raised to negative n), divided by r.
PV is the lump sum. PMT is the monthly annuity check. The variable r is the monthly discount rate you are solving for. The variable n is the number of monthly payments (your expected months of collection). Iterate r until PV matches the lump-sum offer. The annualized IRR is (1 plus r) raised to the 12th power, minus 1.
If the resulting IRR sits below what a low-cost portfolio can plausibly earn over that horizon, the plan is offering you a rich lump sum. If it sits above that hurdle, the annuity is the better deal in expectation, provided you live long enough to collect it.
A worked example: $400,000 lump sum vs. $2,200 monthly annuity
A 65 year old participant is offered either a $400,000 lump sum today, or a $2,200 per month single-life annuity starting immediately. The plan has already applied any early-retirement reduction. The question is which path has the better implied return at various life spans.
Using the present-value formula and iterating the discount rate, the implied annualized IRR looks like this:
Read this chart carefully. If the participant dies at age 80, the annuity stream returns roughly zero: total nominal cash back to age 80 is $396,000, less than the lump sum. At age 85, the return climbs to about 2.9%. Only at age 90 and beyond does the annuity clear a 4%-plus IRR.
Two adjustments matter next: whether the annuity has a survivor benefit for your spouse, and what taxes you owe on each path. Both are covered below.
Adjusting for a joint-and-survivor payout
If you are married under a private-sector defined-benefit pension, ERISA requires the plan to default your election to a Qualified Joint and Survivor Annuity unless your spouse consents in writing to a different form. That default reduces the monthly check.
The reduction is actuarial: a 50% survivor form might drop the $2,200 single-life amount to roughly $1,950 with 50% of that continuing to the spouse. A 100% survivor form drops it further, often near $1,800, with the full amount continuing. Exact reductions depend on ages and plan factors. See the joint-and-survivor annuity election page for the mechanics and paperwork.
Redo the IRR math using the reduced monthly amount and joint life expectancy (either spouse still alive), which is longer than single life expectancy for a couple the same age. A same-age couple aged 65 has a joint life expectancy near 92. That extra tail makes the survivor annuity more valuable than the single-life IRR suggests.
The PBGC backstop on the annuity path
The annuity path carries counterparty risk if the plan sponsor fails. The Pension Benefit Guaranty Corporation insures most private-sector defined-benefit plans up to a statutory maximum that resets each year. If the plan is terminated with insufficient assets, PBGC steps in and continues payments up to the guarantee limit.
For a single-employer plan participant who starts benefits at age 65, the PBGC maximum guarantee is published annually and typically exceeds $85,000 per year in recent tables. Payments starting before or after 65 are adjusted by an age factor. Married elections that include a survivor benefit reduce the maximum, in the same proportion the plan itself would apply.
The relevant point for the decision: an annuity paying below the PBGC maximum from a plan you trust to remain solvent is durably insured. See the PBGC guarantee limits by year for the current-year figures, and always confirm the exact limit that applies to your election form.
Income-tax comparison
The two paths hit your tax return differently. A lump sum paid directly to you is fully taxable in the year received, at ordinary income rates, and the plan withholds 20% on the way out. Rolling the lump sum into a traditional IRA via a direct trustee-to-trustee transfer defers tax until you take distributions.
A monthly annuity is taxed as ordinary income in each year you receive it. There is no lump-year tax bracket shock. For a retiree already in a low bracket, that annual treatment can produce a lower lifetime tax bill than a lump-year cashout. It also protects against IRMAA Medicare-premium cliffs that a single-year lump-sum income spike can trigger.
If you plan to invest the lump sum for growth, the direct-rollover path is almost always the right choice. A direct payout to you triggers immediate tax plus withholding and burns the money’s tax-deferred status.
Sequence-of-returns risk on the invested lump sum
The IRR comparison assumes the lump sum earns a steady return. Real portfolios do not. Sequence-of-returns risk is the effect that early poor years can have on a portfolio being drawn down, even when the long-run average return is fine.
A retiree who rolls a lump sum into a portfolio and pulls monthly income out of it is exposed to that sequence. Two identical retirees with identical average returns can end up decades apart in wealth depending on the order of returns in the first ten years. See the sequence-of-returns risk page for the mechanics.
The annuity path does not carry this risk. The insurer or plan pools mortality across many lives and pays regardless of what markets do in your first ten retirement years. That reliability is worth a lower headline return to many retirees, especially those without a large buffer of other assets.
Guaranteed income vs. legacy asset
The two paths differ on estate outcomes as well as return. A lump sum rolled into an IRA remains an asset your heirs can inherit under the SECURE Act 10-year rule. Any amount you have not spent at death passes on. An annuity, absent a period-certain rider or a joint-and-survivor election, ends when the last covered life dies.
Retirees who prioritize a bequest to children or a charity gain from the lump-sum path even when the IRR math tilts toward the annuity. Retirees who prioritize a floor of income they cannot outlive gain from the annuity path even when the IRR math tilts toward the lump sum. The choice is a values decision after the math, not a substitute for it.
The relative-value disclosure the plan owes you
Under Internal Revenue Code Section 417(a)(3) and Treasury Regulation Section 1.417(a)(3)-1, the plan must furnish a written relative-value comparison for every optional form of benefit against the plan’s qualified joint and survivor annuity. The disclosure states the actuarial present value of each option as a percentage or dollar equivalent of the QJSA.
If the relative-value statement shows the lump sum at a value equal to or above the QJSA, the plan considers the offer fair to you at its assumed discount rate. If it shows the lump sum below, the plan is offering less value than the annuity at the plan’s own rates. Read the statement. Ask for it in writing if the packet does not include one.
When health favors the lump sum
The IRR math assumes an average lifespan. A participant with a serious diagnosis and a shortened expected lifespan flips the calculation. If honest medical judgment puts life expectancy at 75 or below, the annuity IRR is deeply negative on our example. The lump sum, rolled to an IRA, preserves the full remaining balance for heirs.
This is a private decision, not one the plan can factor. It is the single most defensible reason to elect the lump sum against the default. Document the reasoning contemporaneously if you are the participant, and coordinate with a spouse whose survivor rights you are asking to waive.
When longevity insurance economics favor the annuity
The annuity is longevity insurance. The plan pools you with participants who die early and pays you extra years if you outlive the pool. The value of that insurance is highest when you have few other guaranteed-income floors, when you are in good health at retirement, and when a same-age spouse would also collect under a survivor election.
Consider a participant with Social Security as the only other guaranteed income and few other assets. The annuity’s IRR at age 90 or 95 is not a lucky outcome for that profile, it is the base case. Under those inputs, the annuity typically wins by 100 to 200 basis points versus a plausible portfolio return net of fees.
Sources cited
- Pension Benefit Guaranty Corporation, Maximum Monthly Guarantee Tables
- Internal Revenue Service, Rollovers of Retirement Plan and IRA Distributions
- 26 CFR 1.417(a)(3)-1 (Legal Information Institute, Cornell Law School), Required Explanation of Qualified Joint and Survivor Annuity and Qualified Preretirement Survivor Annuity