Mortality credits are the extra income an annuity can pay you because the people in your risk pool who die early leave their money behind for those who live longer. An insurer collects premiums from thousands of buyers, invests the pool, and pays each survivor for life. Every death inside the pool releases funds that get redistributed to the remaining annuitants, and that redistribution is what lets a life-only annuity pay a 65-year-old north of 7% a year while a 30-year Treasury yields roughly 5%. The gap between those two numbers is almost entirely the mortality credit, and it widens every year you keep breathing.
The Three Layers Inside Every Annuity Payment
Picture a monthly annuity check as a stack of three things. The first layer is a return of your own premium. The second is interest earned on the pooled assets, mostly bonds. The third is your share of the funds left behind by pool members who died during the year. That third layer is what makes annuity math different from bond math.
A 30-year Treasury hands your principal back in full at maturity, so its yield reflects pure income on money you still own. An annuity never returns principal as a lump sum. It blends principal, interest, and mortality credits into every payment, which is why the headline distribution rate on an annuity can run well above a bond’s yield even when the underlying investments are similar.
The redistribution is not a gift from the insurer. It is written into the contract the moment you buy. When you choose a life-only annuity, you accept that any balance remaining at your death stays in the pool. In exchange, you get payments higher than any conventional investment can safely produce, and a promise that they keep coming no matter how long you live. The insurer is being actuarially precise, not generous.
The whole arrangement rests on the law of large numbers. No individual knows when they will die, but with thousands of participants the actual death rate in a pool closely tracks the statistical average. Individual uncertainty becomes collective predictability, which is the only reason the insurer can promise a lifetime check in the first place.
Why Mortality Credits Grow With Age
Mortality credits start small and accelerate, and that acceleration is the real engine of lifetime income. At 65, the yearly probability of death inside a healthy annuity pool is low, so the amount being redistributed per survivor is modest. By the late 80s the math changes sharply, because a shrinking survivor pool splits an ever-larger share of forfeited funds.
Research from LIMRA puts numbers on it. To self-fund $15,000 of annual spending at age 88 out of a bond portfolio, a retiree would need roughly $229,000 set aside. Inside an annuity pool, the per-person cost of funding that same $15,000 is far lower, because only the surviving members have to be paid. The difference, about $27,000 at age 88, is the mortality credit. By age 100, that credit grows to roughly $76,000 for the same $15,000 of income. By 104, it reaches about $89,000.
This is where annuities earn their keep. A retiree who self-insures against longevity has to save for the worst case, which could mean living past 100. An annuity pool only has to fund the average case, because every early death subsidizes every late one. The longer you live, the better the trade looks.
What Determines Your Payout Rate
Several variables shape how much income each dollar of premium buys.
Age at purchase is the biggest lever. An older buyer faces a higher annual probability of death, which means a larger share of the pool’s mortality credits flows through each payment. Current rates for life-only immediate annuities run around 7% to 8% of premium for a 65-year-old and push past 10% for someone buying at 80 or older.
Gender matters for annuities bought individually. Women statistically live longer, so a 65-year-old woman receives a slightly smaller annual payment than a 65-year-old man buying the same contract, because she is expected to collect for more years. Employer-sponsored plans work differently. The IRS adopted gender-neutral annuity tables in 1986, so payout rates inside those plans are the same regardless of sex.1Internal Revenue Service. Publication 939, General Rule for Pensions and Annuities
Interest rates at the time of purchase move the interest layer up or down. Insurers invest premiums primarily in bonds, so a higher-rate environment produces larger payments. Someone who locked in an annuity in 2020 is receiving meaningfully less than someone buying the identical product in 2025.
Contract features cut into the mortality credit layer. Any guarantee that returns money to a beneficiary, any inflation adjustment, or any second life added to the contract forces the insurer to hold back more of the premium, and your payment drops accordingly.
How Death Benefit Options Reduce the Credit
A life-only annuity pays the most because it maximizes mortality credits. Die six months after buying it and the remaining balance stays in the pool. That is the trade that funds the bigger checks for everyone else.
Most buyers are not comfortable with that gamble, so insurers offer options that protect against early death at the cost of a smaller payment:
- Period certain guarantees payments for a fixed stretch of years, commonly 10 or 20, even if you die before the period ends. A beneficiary collects the balance. A 10-year period certain typically trims the payout rate by a modest amount.
- Cash refund pays your beneficiary the difference if you die before total payments equal your original premium. It cuts the payout more noticeably, because the insurer is guaranteeing your premium is never lost to the pool.
- Installment refund works the same way but pays the beneficiary in installments rather than a lump sum, which costs the insurer slightly less and reduces your payment slightly less.
The logic is clean. Every dollar the insurer may owe a beneficiary is a dollar that cannot be redistributed as a mortality credit to survivors. A life-only annuity for a 65-year-old woman might pay roughly 5.8% of premium; the same contract with a cash refund option might pay about 5.4%. That 0.4-point gap compounds over decades.
Joint and Survivor Annuities Dilute the Credit Further
Couples who want income that continues after the first death can buy a joint and survivor annuity, which covers two lives instead of one. The pool now has to wait for both annuitants to die before releasing anything, and the odds of at least one spouse surviving to any given age are much higher than for a single person. That dilutes the mortality credit each spouse receives.
TIAA’s disclosure materials show the impact on a $100,000 annuity starting at age 65. A single-life contract pays roughly $6,779 a year. A joint annuity that continues full payments to the surviving spouse drops to about $5,880, a 13% reduction. A joint annuity that continues at 50% to the survivor sits at about $6,298.2TIAA. Relative Value Disclosure Illustration A younger spouse pushes the reduction higher, because the insurer expects to pay for a longer total period.
Joint annuities are often the right call for couples who both depend on the income. Just know what you are giving up. The mortality credit advantage that made the annuity attractive gets thinner when two lives are on the contract.
Deferred Income Annuities and QLACs Concentrate the Credit
The most dramatic use of mortality credits is a deferred income annuity, where you pay the premium today but payments do not start until a future date, often 80 or 85. During the deferral period, the premium earns investment returns and a large portion of the original buyers die before ever collecting a payment. Both effects stack on top of each other.
The math is striking. Buying a deferred income annuity at 65 with payments starting at 85 can produce a payout rate of roughly 65% of the original premium per year once payments begin, against about 7% for an immediate annuity bought at the same age. The catch is that you receive nothing during the 20-year wait, and you forfeit the premium entirely if you die before payments start, unless you added a death benefit rider.
A specific kind of deferred income annuity, the Qualified Longevity Annuity Contract (QLAC), lets retirees use money from traditional IRAs and 401(k) plans to buy longevity insurance. QLACs are capped at $210,000 per person for 2026, and the income start date can be deferred as late as age 85.3Internal Revenue Service. Notice 25-67, 2026 Amounts Relating to Retirement Plans and IRAs QLAC premiums are also excluded from the account balance used to calculate required minimum distributions, which lowers taxable income during the deferral years.
How the IRS Taxes a Payment Full of Mortality Credits
The IRS has no separate tax bucket for mortality credits. It taxes every annuity payment under a framework called the exclusion ratio, laid out in Section 72 of the Internal Revenue Code.4Office of the Law Revision Counsel. 26 USC 72 – Annuities; Certain Proceeds of Endowment and Life Insurance Contracts
The ratio splits each payment into a tax-free return of your premium and a taxable portion representing the gain. The IRS calculates it by dividing your total investment in the contract by the expected return over your lifetime. Invest $200,000 against an expected return of $400,000 and the ratio is 50%, so half of each payment is tax-free and half is taxable as ordinary income.5eCFR. 26 CFR 1.72-4 – Exclusion Ratio
Here is the twist that catches people off guard. If you outlive the IRS’s expected return period and fully recover your original investment, the exclusion ratio drops to zero. Every dollar of every payment after that is fully taxable as ordinary income.1Internal Revenue Service. Publication 939, General Rule for Pensions and Annuities Those later payments are funded almost entirely by mortality credits and interest, and the IRS treats them accordingly. For someone living well past life expectancy, exactly the scenario where annuities shine, the tax bill on each check is higher than it was in the early years.
Annuities bought inside tax-deferred accounts like traditional IRAs or 401(k) plans skip the exclusion ratio entirely. The premiums were never taxed, so every dollar of every payment is taxable as ordinary income.
Will the Pool Actually Be There?
Mortality credits only work if the pool stays solvent for decades. Insurers build in margins at both ends. On the pricing side, actuaries use mortality tables with built-in improvement factors, projecting that each generation of retirees will live longer than the last, which keeps the pool from being underfunded if longevity keeps rising. On the reserving side, the National Association of Insurance Commissioners requires life insurers to hold reserves calculated under multiple scenarios and keep the largest figure, so claims can be paid even under pessimistic assumptions about markets and longevity.6National Association of Insurance Commissioners. Principle-Based Reserving
If an insurer fails anyway, every state operates a life and health insurance guaranty association that pays claims up to a limit, funded by assessments on the other insurers doing business in the state. Coverage centers on $250,000 per person for annuity contracts in most states. Connecticut, New York, Utah, and Washington go up to $500,000, and Arkansas, North Carolina, Oklahoma, and South Carolina set the limit at $300,000.7NOLHGA. How You’re Protected Some states apply different limits to deferred versus in-payout annuities. Protection follows your state of residence, not the state where you bought the policy.
Any present value above the limit becomes a general claim against the failed insurer, which may pay a fraction of face value or nothing at all. That is why large annuity purchases are often split across unrelated insurers, with each contract kept under the guaranty limit in the buyer’s home state.
Who Benefits Most From Mortality Credits
Mortality credits deliver the most value to buyers who are healthy, expect a long retirement, lack a pension, and need a baseline income they cannot outlive. The longer you survive past the group average, the more the pool’s math works in your favor. A 65-year-old looking at potentially 30 more years of spending faces real longevity risk, and a partial annuity allocation can address it efficiently.
The cost of entry is irreversibility. Once premiums go into the pool, they are generally gone. If you need liquidity for medical bills, home repairs, or a change in plans, annuitized money is usually unavailable. If you die earlier than expected, the pool keeps what you leave behind unless you paid for a death benefit guarantee, which cut your payments to begin with. People with serious health conditions, those already covered by a pension, and those who need full access to savings may not get enough from mortality credits to justify locking up capital.
The strongest use case is partial annuitization: convert enough of a retirement portfolio into annuity income to cover fixed expenses like housing, food, and insurance, and keep the rest invested for flexibility and growth. That captures the mortality credit advantage on the bills that have to be paid every month without surrendering all liquidity.