Stress-test your plan

What "stress-testing" means

Your main forecast is a single, steady projection: it assumes your investments earn exactly what you expect, every year, with no surprises. Real life isn't that tidy. Stress-testing asks the harder question — how does your plan hold up when things don't go to plan? Bad market years, higher-than-expected costs, a different Social Security claiming date, and so on.

You'll find all of this on the Forecast tab, under Stress-test your plan. It's one surface with a row of buttons at the top — the lenses. You pick a lens, and the panel below changes to show that view. Your plan is never altered; these are all read-only "what would happen if…" tools.

Stress-testing is a premium feature. See Accounts and billing for what free and premium include.

The five lenses

Odds of success (Monte Carlo). Instead of one steady projection, this runs about 500 projections with randomized, year-by-year investment returns and reports the share that never run out of money — your probability of success. It's the honest answer to "but what if the market misbehaves?" See Odds of success.

What-if levers. One-click previews of a single change — spend 10% less, work two more years, returns 2% lower, and so on — each showing how it moves your run-out date and ending balance. Nothing is saved; it's a side-by-side preview. See What-if levers and Social Security timing.

Social Security timing. Compares claiming Social Security at 62, 65, 67, and 70, showing each age's monthly check and its effect on how long your money lasts. Later means fewer but larger checks. Same page: What-if levers and Social Security timing.

Roth conversions. Compares moving money from a 401(k)/IRA into a Roth in the low-tax years before Required Minimum Distributions start, filling different tax brackets, and ranks them by what your heirs would actually keep after tax. The Medicare and ACA cliffs are priced in. See Roth conversions.

AI review. A grounded assistant that reads your actual results — the projection, the odds of success, the what-if outcomes, Social Security timing, and how your plan compares to your real spending — then suggests concrete moves. You can also ask it a question. See AI review.

Some lenses only appear when they apply

You won't always see all five buttons, and that's on purpose:

• What-if levers appears only when at least one lever is relevant to your plan. For example, "Delay Social Security" only shows if you have a Social Security income stream; "Work two more years" only shows if you have wage income with an end date.
• Social Security timing appears only when your plan includes a Social Security income stream (with a birth date entered, so the app can turn ages into dates).

Odds of success and AI review are always available.

How to read the results

Every lens is an educational estimate, not financial or tax advice. They're tools for comparing choices — "which direction helps, and roughly how much?" — not predictions of exactly what will happen. When a term is unfamiliar, check the glossary.

Ready to dig in? Start with Odds of success.