Guides
Plain-English explainers of the concepts that drive retirement planning. Read these before you run the simulator, or after, or both.
What is a Monte Carlo simulation?
A Monte Carlo simulation is a way to test a plan against thousands of possible futures instead of one. For retirement planning, it tells you not just "will this probably work?" but "in what share of plausible market sequences does this work?" That difference matters more than most calculators let on.
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The Rule of 55 explained
The Rule of 55 is an IRS provision that waives the 10% early-withdrawal penalty on distributions from your current employer's 401(k) or 403(b), provided you separate from service in the year you turn 55 (or later). It's the single biggest tax-bracket lever for early retirees, and it has a few traps that destroy eligibility before people realize it.
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Health insurance before age 65
Medicare doesn't start until you turn 65. If you retire before that, you need a separate health insurance plan for every month in between. For someone retiring at 55, that's a 10-year bridge. For a couple, it's 20 person-years of coverage. This guide walks through the three real options and how to think about cost.
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Go-go, slow-go, no-go: how retirement spending changes
Retirees do not spend the same amount every year. Spending follows a pattern: high in the first decade (the "go-go years"), lower in the second decade ("slow-go"), then shifting heavily to healthcare in the third ("no-go"). Calculators that assume flat inflation-adjusted spending overstate your funding need.
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Sequence-of-returns risk
Sequence-of-returns risk is the chance that a bad market sequence early in retirement permanently impairs a portfolio that would otherwise have worked. The same long-run average return can produce wildly different outcomes depending on the order in which the good and bad years arrive, and the early years matter the most.
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