Definition
Mortality improvement is the systematic decline in age-specific mortality rates over successive calendar years, observed across most developed-country populations over the past century and central to projecting future mortality experience.
Why it matters
Mortality improvement is why people born more recently tend to live longer than people born earlier did at the same age. Measuring the improvement is part of how actuarial science separates persistent trend from current-year noise, and it is one of the central uncertainties in pricing arrangements with long planning horizons.
How it works
Mortality improvement refers specifically to year-over-year declines in age-specific mortality rates, distinguishing it from gains in life expectancy that can also be driven by changes in age distribution or in causes of death. The improvement rate is itself age-specific: improvement has been strongest at the oldest ages over the past several decades, with more modest improvements at younger adult ages. Concrete pattern: US female mortality at age 70 was approximately 2.2% per year in 1980, fell to approximately 1.4% by 2000, and to approximately 1.1% by 2020 — a relative improvement averaging roughly 1.7% per year over four decades. The improvement is neither uniform across years nor across causes, and recent years have seen episodes of deterioration (notably during the 2020–2021 pandemic) that complicate trend extraction. Actuarial practice handles this through formal mortality improvement scales — schedules of year-over-year improvement assumed for each age — that are applied to a base mortality table to project future experience.
In practice
For an individual, mortality improvement means that the life-expectancy figures their parents or grandparents used at the same age are systematically lower than what current data would produce — a point routinely missed in retirement planning conversations that rely on intuitive benchmarks. A professional building a long-horizon projection should explicitly state whether mortality improvement is assumed, what scale is in use, and how sensitive the projection is to the assumption. Plan fiduciaries evaluating in-plan lifetime income options should understand whether the pricing reflects projected mortality improvement, because pricing that ignores it understates the cost of deferred and long-dated products.
In the Longevity Standard Framework
Mortality improvement is supporting vocabulary in the Longevity Standard framework. The framework's actuarial model uses Society of Actuaries credibility scaling that incorporates a baseline level of mortality improvement; departures from the assumed improvement trend are part of systematic longevity risk in the framework's vocabulary. The framework treats mortality improvement as a structural feature of the mortality input rather than as a discretionary assumption — the cost-of-income comparison is sensitive to whether the improvement assumption applied to the survival curve is conservative, neutral, or aggressive.
Related terms
- Mortality rate
- Cohort effect
- Survival curve
- Mortality improvement scale
- Projected mortality table
- Period life table
- Cohort life table
- Systematic longevity risk