Retirement Income Planner

The markets. Each market is a sequence of yearly returns drawn from a lognormal distribution with your average and volatility. One draw a year moves every account together. The draws are seeded, so the same inputs give the same answer until you ask for new markets. Inflation, Social Security and pensions follow the plan in every market.

Each year. The same loop as the Roth Conversion Planner: the RMD on the January balance, any conversion, then spending, drawn in the order you chose. Taxes and withdrawals are solved together to the cent. A market counts as a success only if spending was fully met every year.

Taxes. 2026 federal brackets and deductions, the senior deduction through 2028, Social Security taxed per IRS Pub. 915, capital gains stacked at 0%, 15% and 20%, the 3.8% net investment income tax, and IRMAA on a two-year lookback. A sale below basis realizes a loss, which offsets gains and up to $3,000 of other income a year and carries forward.

Steady return. Volatility drags on compounding: a 6% average with 12% volatility grows a dollar like a steady 5.3%. The year-by-year table and the spending a steady market carries use that rate, so the table tracks the middle of the fan, not its top half.

Guardrails. Each January the household compares its withdrawal rate, spending not covered by income over the portfolio, with the rate its plan expected for that year at the steady return. If the plan itself would run dry, the comparison is to the most a steady market could carry. More than the band above, spending is cut; more than the band below, it is raised. Moves persist and stop at the limits you set.

Longevity. The plan runs to the age you set in every market. The chance of running out while someone is alive weighs each failure by the SSA 2021 period life table's odds, scaled for health, that you or your spouse is living at that age, treating markets and lifespans as independent.