1. Guaranteed income & life events reduce portfolio need

One-time windfalls (age-matched) are deposited straight into brokerage as new cost basis, not netted against spending.

2. Traditional withdrawal (ordinary income + state tax)

Flat mode: grossNeeded = netNeed / (1 − ordinaryRate − stateRate)

Bracket mode: federal tax is the incremental progressive tax the withdrawal causes on top of other ordinary income; state tax is a flat add-on. Gross is solved by bisection so that:

3. Brokerage withdrawal (capital gains + state tax)

Flat mode: gain taxed at your flat capital gains rate. Bracket mode: gain stacks on top of ordinary taxable income for the year and is taxed using 2025-ish federal LTCG brackets (0% / 15% / 20%). Either way, state tax is gain × stateRate. Cost basis shrinks proportionally to what's sold.

4. Roth & RMDs

Roth withdrawals are always tax-free. If RMDs are enforced, the IRS Uniform Lifetime Table sets a minimum traditional withdrawal each year past the RMD age; any shortfall versus your strategy is forced, taxed, and the after-tax leftover is reinvested into brokerage as new cost basis.

5. Age locks

No withdrawals occur before your withdrawal start age (accounts just compound). Traditional and Roth are always off-limits before age 59, regardless of settings — only brokerage is usable in that gap, and any unmet spending is reported as a penalty-locked shortfall.

6. Growth — deterministic vs. Monte Carlo

In Monte Carlo mode, each simulated year draws one shared random shock z (standard normal) and applies it scaled by each account's own volatility:

Hundreds of simulated paths are run; the chart's shaded band shows the 10th–90th percentile of total balance each year, and "success probability" is the share of runs that never hit zero.

7. Survivor mode

At the spouse's death age, filing status switches from MFJ to Single (brackets and standard deduction re-based to the Single schedule, carrying forward the same cumulative inflation already applied) and Social Security drops to the survivor benefit you specify.

8. Inflation

Spending target, guaranteed income, LTC cost, tax brackets, and the standard deduction all compound at your inflation rate every year: