Trust explainer
SimuPlan is designed to show the assumptions, calculations, and tradeoffs behind each result. The goal is not to predict the future with certainty, but to make retirement planning clearer, more transparent, and easier to test.
Balances, income, spending, retirement age, assumptions
Inflation, growth, taxes, withdrawals, Social Security, healthcare
Projections, tax estimates, simulations, scenario comparisons
Balances, shortfall/surplus, success probability, drivers, insights
SimuPlan's deterministic projection engine builds a baseline retirement path using starting balances, contributions, spending, inflation, growth assumptions, withdrawals, taxes, and ending balances. The tax engine is designed for long-term planning and scenario analysis, not tax filing.
SimuPlan is not tax-preparation software. Tax calculations are intended for planning and comparison, not filing returns.
SimuPlan includes planning-grade tax estimates so users can compare retirement scenarios with more context. The goal is practical transparency, not tax filing or a dense tax-law manual.
Inside the app, the Methodology view shows a more detailed modeled-vs-simplified breakdown for users who want the deeper assumptions.
Runs many randomized future market paths around the plan's expected-return assumptions. Completed investment-mix setup enables shared stock, bond, and cash movements and generic single-company concentration risk; otherwise the standard randomized model is used.
What it teaches: how sensitive the plan may be to uncertainty.
Tests complete rolling windows of monthly market history across the planning horizon, using a Robert Shiller-based market dataset. Historical CPI is on by default, with an option to use the plan's fixed inflation assumption. Completed investment-mix setup determines stock, bond, and cash exposure; incomplete setup retains the legacy allocation inferred from expected returns.
What it teaches: how past market environments would have challenged the plan.
Begins the projection with a selected historical event using the same allocation rules as historical windows, then returns to the plan's configured returns for the remaining years. A separate historical CPI option is off by default.
What it teaches: why sequence-of-returns risk matters.
Investment-mix boundaries: Mixes are weighted by current balances within planning account groups. Historical periods use broad stock and bond returns; individual stocks and alternative investments use broad stock-market history. All-cash groups keep their configured return, while cash within a mixed group receives no additional growth. These settings affect simulation-based comparisons and reviews, not account balances, tax treatment, or the central projection.
A funded path can still miss the retirement target. Historical windows overlap, and a combined funded percentage across different simulation types is a summary of the tests, not a prediction of future success.
During development, SimuPlan's projection, tax, randomized Monte Carlo, and historical simulation engines were benchmark-tested against other respected planning tools under comparable assumptions. The goal was to keep results within a tight tolerance where assumptions overlap, investigate differences, and harden the model.
Different tools can still produce different results because they may use different assumptions, tax simplifications, return models, withdrawal ordering, or rounding rules.
Two retirement calculators can both be reasonable and still produce different answers. The assumptions matter.
Explore the demo plan to see how SimuPlan connects assumptions, projections, simulations, and plain-English explanations before entering your own numbers.
Inputs
Assumptions
Calculations
Outcomes