How is this different from a retirement calculator that uses one tax rate?

A flat-rate calculator applies one average tax assumption. The Retirement Planner calculates federal and state taxes each year, then tracks account-specific withdrawals, RMDs, long-term gains, NIIT, taxable Social Security, and optional IRMAA.

Does the Retirement Planner model ACA subsidies?

Not currently. Use the Roth Conversion Planner or Decumulation Studio when ACA premium tax credits are part of the decision. Both read ACA inputs from the saved household tax context.

Do I need Pro to run a simulation?

The full configuration form is open to everyone. Running a plan requires Pro because each analysis simulates tax-aware withdrawals against your saved household.

Tax-Aware Retirement Simulator

ArthaPilot

The Tax-Aware Retirement Simulator tests one household spending plan across historical and Monte Carlo paths, with calculated yearly taxes and account-specific withdrawals.

Model my household plan

Pinned household example

One plan, 70 historical starting points

The plan funds all 30 years in 58 starts and runs short in 12. A median result alone misses that sequence risk.

58 funded 30 years

12 ran short

Outcome	Value
Median ending balance	$449,000 at age 95
Median failed path	First shortfall at age 90
Worst sequence start	1929

Inputs used

Household plan

$1,000,000 total: $300,000 taxable, $600,000 traditional, $100,000 Roth; $42,000 fixed-real annual spending from age 65 through age 94; terminal balance at age 95

Portfolio

60% U.S. stocks, 40% U.S. bonds; 65% taxable cost-basis ratio

Tax and scope

Single filer in California; progressive 2026 tax model; historical paths only; no added income streams or IRMAA

History and policy

Historical annual real returns: 1926–2024; 1926–1927 are retained pre-source static extensions, and the cited source starts in 1928. Withdrawal order: taxable, then traditional, then Roth. Roth conversions: disabled.

Engine-backed sample from pinned inputs. Tax kernel unified_v1. Values are in today's dollars.

Modeled estimate, not a withdrawal, conversion, or filing recommendation.

Before you run it

Link the household you want to model, then confirm account balances, cost basis, filing status, state, spending, and the projection horizon.

FAQ

How is this different from a retirement calculator that uses one tax rate?: A flat-rate calculator applies one average tax assumption. The Retirement Planner calculates federal and state taxes each year, then tracks account-specific withdrawals, RMDs, long-term gains, NIIT, taxable Social Security, and optional IRMAA.
Does the Retirement Planner model ACA subsidies?: Not currently. Use the Roth Conversion Planner or Decumulation Studio when ACA premium tax credits are part of the decision. Both read ACA inputs from the saved household tax context.
Do I need Pro to run a simulation?: The full configuration form is open to everyone. Running a plan requires Pro because each analysis simulates tax-aware withdrawals against your saved household.