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The basics
Plan Resilience is not a confidence that the future will happen a certain way. It reruns the same plan across many plausible orderings drawn from the history in the selected series and summarizes the spread of outcomes.
Illustrative numbers
How to read a result
Repeated runs300 (the default)
Runs with no shortfall246
Observed success share82%
A run that had to sell a permitted property still counts here if it covered every year; the screen reports that outcome separately. It also shows a Wilson 95% interval—a standard uncertainty range for a share estimated from a finite sample. Neither 82% nor that interval is a promise about real-world probability.
Calculation transparency
How it works in MoneyWhatIf
- 01
By default the sampler deals 20-year stretches of the chosen historical series, never dealing one calendar year to the same run twice, so nearby-year structure survives while the longer sequence changes. Four other dealing methods are offered: history restarted at a random year, one unbroken stretch, 5-year blocks redrawn with replacement, and every year drawn at random.
- 02
Accounts already following a market use the dealt sequence as-is. Eligible fixed-rate accounts borrow its ups and downs but are rescaled to compound to their chosen long-run return; cash accounts remain on their cash path.
- 03
Each generated path reruns the full funded plan. A run succeeds when no year closes more than $0.50 below zero, even if a permitted home had to sell. Results feed clean, forced-sale, and shortfall counts plus 10th / 25th / 50th / 75th / 90th percentile bands; at a given year, a percentile is the net-worth level at or below which that share of runs falls.
- 04
The page offers 100, 300, or 500 runs. The seed makes a deal reproducible; “Deal it again” changes the seed and reshuffles it.
- 05
Inflation can be lived year by year at what each run’s dealt calendar years historically cost (the default, summarized as the rate those years compounded to), held at the plan’s rate or another fixed rate, or drawn once per run from a range or a bell-shaped distribution.
Keep in mind
Model limits
The output depends on the available historical series, block design, number of runs, and the model’s definition of plan safety.
Taxes, policy, inflation, returns, and household behavior can differ from the modeled relationships.
Percentiles summarize model runs; they are not investment guarantees or a substitute for considering risks absent from the data.
This explanation documents the planning model. It is educational, not individualized tax, legal, Medicare, or investment advice.
Where it appears
Where to use it
See this concept in context, with a guide to each page and its controls.
The words behind it
Related financial terms
Plain-English definitions, with 2026 figures and worked examples, from the financial terms glossary.