Definition
Planning horizon risk is the risk that an individual using solo drawdown selects a chosen planning age and outlives it, exhausting savings before death, and is the specific form longevity risk takes when income is bounded by a self-selected horizon rather than paid for life.
Why it matters
Solo drawdown requires choosing a planning age, and that choice has consequences the conventional withdrawal-rate conversation tends to obscure. The longer the planning age chosen, the lower the annual income each saved dollar produces; the shorter the planning age, the greater the probability of outliving the plan. Planning horizon risk names this tradeoff directly and distinguishes it from longevity risk in general — longevity risk is the underlying uncertainty about how long an individual will live; planning horizon risk is the specific risk that arises when that uncertainty is converted into a finite income horizon by the structure of solo drawdown.
How it works
Planning horizon risk operates in three steps. First, the individual selects a planning age — for example, 90, 95, or 100 — at which the solo drawdown plan is calibrated to exhaust savings. Second, savings are drawn down on a schedule that depletes the balance at the chosen age. Third, if the individual lives past the planning age, no further income is available from the depleted savings. The probability of outliving the planning age can be read directly from the survival curve: a focal individual (67F) has approximately a 90th-percentile survival to age 98 and a 99th-percentile survival to age 105, which means that planning to 90 leaves a meaningful probability of living beyond the planning horizon. Planning horizon risk is specific to solo drawdown because pooled and transferred-risk arrangements pay for life — they have no finite planning horizon to outlive — and so they convert longevity uncertainty into income variability or contractual income certainty rather than into financial exhaustion.
In practice
For an individual managing their own retirement savings, planning horizon risk is one of the two structural risks that solo drawdown forces them to bear — the other being sequence-of-returns risk — and it is the risk most directly addressed by considering whether any portion of the income should be pooled or insured. The conventional "what's a safe withdrawal rate?" framing tends to embed a planning horizon assumption that the individual never sees explicitly; a better conversation surfaces the planning age as a stake and asks what the consequence would be of living past it. Lifetime income arrangements eliminate planning horizon risk by paying for life; the cost of that elimination is what the cost-of-income framework measures. For an individual unwilling to bear planning horizon risk at any level, even partial pooling of the tail risk through a deferred income annuity or a QLAC can shift the risk substantially while preserving most of the drawdown flexibility.
In the Longevity Standard Framework
Planning horizon risk is supporting vocabulary in the Longevity Standard framework, used to name the structural risk that arises specifically from the solo drawdown arrangement. It is the analytical mirror to the cost of extra protection: the cost of extra protection measures what it costs to extend the planning horizon under each arrangement; planning horizon risk measures what the individual bears when the horizon is not extended. The two terms together describe the structural tradeoff that solo drawdown forces and that pooled and transferred-risk arrangements resolve. Planning horizon risk is distinct from longevity risk in the same way sequence-of-returns risk is distinct from market risk — both are arrangement-specific expressions of a more general underlying uncertainty.
Related terms
- Solo drawdown
- Cost of extra protection
- Longevity risk
- Longevity tail risk
- Sequence-of-returns risk
- Safe withdrawal rate
- Self-annuitization
- Frictionless pool