Mortality Table

Mortality tables, sometimes called life tables, are among the oldest statistical tools in finance. The basic structure is straightforward: for each age from birth (or policy issue) through the maximum modeled age, the table records the number of individuals alive at the start of that year out of a standard cohort, the number expected to die during that year, and the resulting probability of death. Actuaries then use those probabilities to calculate expected claims costs and price policies accordingly.

In the United States, the insurance industry relies on standardized mortality tables developed and periodically updated by organizations such as the Society of Actuaries (SOA) and the American Academy of Actuaries. The Commissioners Standard Ordinary (CSO) mortality table is the most widely referenced benchmark for individual life insurance and is incorporated into state insurance regulations. Regulators require insurers to maintain reserves sufficient to pay future claims, and those reserves are computed using approved mortality tables. The 2001 CSO table was the standard for many years; the 2017 CSO table became effective for new policies in most states after 2019.

Mortality assumptions differ by product type, distribution channel, and underwriting class. Insurers who sell policies through agents with full medical underwriting experience lower actual mortality than the general population because applicants are screened for health conditions — a phenomenon called the select effect. After several years, the effect of initial underwriting wears off as policyholders age and health status regresses toward population norms — the ultimate period. Select-and-ultimate tables capture this two-phase dynamic and are routinely used in pricing individual life products.

Gender has historically been a significant mortality variable — women in the U.S. live longer on average than men — but the use of gender-distinct pricing is regulated and subject to ongoing legal and regulatory scrutiny. Improvements in longevity have also prompted actuaries to use generational or projection tables that extend static period tables by applying annual mortality improvement factors year by year, reflecting the historical trend toward increasing life expectancy. These improvement scales affect long-duration products like whole life and annuities more acutely than short-term term policies.

For policyholders, mortality tables are largely invisible infrastructure, but they directly determine the cost of coverage. Understanding that premiums rise with age precisely because the probability of death in any given year increases with age — as any mortality table illustrates — helps explain why purchasing life insurance at younger ages locks in lower lifetime costs. The same tables also underlie annuity pricing, where longer expected survival translates into lower monthly payments per dollar of premium.