Planning horizon
Choose an end age that tests whether the plan can support a long life without treating it as a prediction.
The planning horizon is the period your financial plan must cover. In Alpha Retire, it ends at the planning age entered for each person.
It is a test, not a forecast
Life expectancy is an average across many people. Your own lifetime may be shorter or much longer. The end age is therefore best understood as a stress-test boundary: How would the plan hold up if the household needs it to last this long?
Choosing a later age adds more years of spending, inflation, taxes, and market uncertainty. It may reduce projected ending assets or Probability of Success, but that does not make the later age “wrong.” It means the plan is being asked to cover more years.
Whose age matters?
For a two-person household, the plan generally needs to continue through the later planning horizon. One person’s death can change benefits, filing status, income, and expenses, but it does not necessarily end the household plan.
Choosing a useful horizon
Use an age that gives the plan a meaningful longevity margin. Then compare nearby ages to see whether the conclusion changes materially. If adding a few years makes the plan fragile, that is useful information: spending flexibility, insurance, retirement timing, or the amount held in reserve may deserve more attention.
Revisit the horizon when health, family history, or household circumstances change. The goal is not to guess the exact year of death. It is to avoid building a plan that works only if life follows one convenient timeline.