Pick modules, fill in the basics, then open results.
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The basics
Age, plan length, target spend
19 controls
Longer-life stress test
Compare the current lifetimes with five extra years for you, your spouse, and both. Uses your selected simulation count, fees, healthcare and survivor budgets, and extends the horizon through both lifetimes.
Symbol / ID accepts a ticker (live quote or previous close), a Treasury TIPS CUSIP (inflation-adjusted principal at par; units = face ÷ $100), or an I-bond purchase month like 2021-11 (official redemption value computed locally; units = face value in dollars). Prices update only when you click refresh — never on their own — and rows that could not update are highlighted with the reason on hover.
Opening Roth conversion history
Enter amounts remaining after past withdrawals, without thousands separators. Owner is primary or spouse. Regular contributions go in the fields above. A checked box with no lines means no remaining conversions. Otherwise, legacy conversion-tagged account rows supply the opening principal once. Securities traded inside a Roth do not change these balances. Roth IRA ordering is modeled; inherited beneficiary IRAs and designated Roth employer accounts require separate treatment.
Opening tax history
IRA basis is the remaining total for each person, not security purchase cost. Include all traditional, SEP, and SIMPLE IRAs, including accounts held elsewhere, in the holdings above. Employer plans and your spouse's IRAs are separate. Opening balances must already include contributions made before the plan starts. Confirm remaining basis against Form 8606.
Investment fees
Advisory fees are an additional annual cash expense based on beginning portfolio value. Fund expenses reduce investment values only when returns are marked gross; use the same convention for Monte Carlo and historical returns. Individual TIPS ladder securities are excluded from the fund-expense charge.
Privacy mode keeps modeling local by disabling Google Sheets imports and live CMS Marketplace plan searches. CSV, JSON, setup backup/restore, offline ZIP lookup, and manual ACA plan inputs remain available.
Google Sheets
Private sheet (OAuth)
JSON editor
Save / Load setup
Ready to import.
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Healthcare
Insurance until Medicare
20 controls
Confirm tax-dependent status, employer coverage affordability/minimum value, Medicaid/CHIP and other coverage eligibility before choosing eligible. The MFS exception must meet IRS requirements; living apart alone does not establish it.
Member coverage calendar
Use primary, spouse, or a dependent name. Eligibility is eligible, employer, medicaid, dependent (claimed by another tax family), or unknown. Only eligible months receive a modeled credit. Enter Marketplace premiums in today’s dollars, before tax credits, without thousands separators. All members and months need their own records; unspecified future years receive no subsidy until confirmed. A dependent you claim can be eligible. The calendar overrides household premium quotes for its specified years.
Silver plan cost-sharing reductions
Household annual amounts in today's dollars, excluding premiums. Enter each variant's actual plan limit and expected covered spending. These replace the OOP-use percentage for the primary plan. Annual MAGI is assumed reported to the Marketplace before enrollment; mixed eligibility uses standard costs. Backup plans retain their separate OOP assumptions. American Indian/Alaska Native and other special CSR variants are not included.
Assumption: ACA subsidy math uses coverage-year household size, marketplace member ages, and prior-year FPL guidelines for the selected tax year.
Plan & premium overrides
Assumption: exact plan mode calculates PTC from the household SLCSP and applies the selected plan gross premium and OOP max. Quoted net premium mode trusts the quote and bypasses PTC recalculation.
Backup plan (high-MAGI fallback)
Assumption: the backup plan becomes active only when modeled ACA MAGI exceeds the trigger, so it can model subsidy cliffs without replacing low-MAGI coverage.
Federal Marketplace plan finder
Assumption: federal Marketplace lookup uses the HealthCare.gov API for FFM states. State-based exchanges are routed to localized benchmarks offline, or accept manual local plan overrides.
ACA plan helper ready.
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Medicare / IRMAA
Premiums after 65
12 controls
IRMAA tax-return history and redeterminations
Modeled lookback years retain their actual filing status. Enter a redetermination only for an approved or separately confirmed SSA-44 assumption; a spouse’s death does not automatically grant relief.
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Other income
Social Security, work, SE
24+ controls
For benefits already received, enter the actual claim age and current annual award. For an unclaimed benefit, enter the estimate at the selected future age. Past elections are locked; claim withdrawal, voluntary suspension, retroactive awards, and exact claim-month cash flows are not modeled.
Claim-month and earnings-test detail
The annual earnings test is automatic before full retirement age. To use the special first-year monthly rule, enter all 12 months and reconcile their total to annual wages plus net self-employment income. Otherwise the annual test applies. In the FRA year, missing monthly detail conservatively treats all annual earnings as pre-FRA earnings. Withheld months adjust future worker benefits at FRA; auxiliary/survivor adjustments require SSA review.
Recurring income streams
Pensions, annuities, rent, and other recurring income: age-started on the owner's clock, optional COLA, survivor share after the owner's death, and state retirement-income treatment for pensions/annuities.
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Strategy toolkit
Taxes, allocations, withdrawal rules
43 controls
Assumption: discretionary spending is 100% when stocks are less than 10% below prior highs, 50% from 10% to 20%, and 0% beyond 20%; essential spending inflates, discretionary spending stays nominal.
Risk-based guardrails solve a fixed failsafe spend, starting spend, lower cut trigger, and upper raise trigger from the selected historical backtest cohorts.
In lifetime mode, automatic harvesting compares projected plans through your full horizon. It may accept higher taxes or premiums now to build cost basis and preserve larger premium tax credits later. The MAGI buffer and annual override still apply.
HSA eligibility and expense history
Starting expense balance is the documented receipt total before the reimbursements/deductions entered here. Only expenses incurred after the HSA was established qualify. ACA premiums and Medigap are excluded by default; enter only a supported insurance exception such as COBRA or coverage while receiving unemployment compensation. Qualified out-of-pocket costs accrue to the receipt pool. Medicare B/D premiums accrue only when all living adults are 65+; mixed-age receipt ownership requires review. Contributions assume eligible HDHP coverage, no disqualifying coverage, and no Medicare enrollment; the model stops contributions at 65. Each spouse’s $1,000 age-55 catch-up goes into their own account and is not inflation-indexed. The last-month rule is not assumed.
Shared allocation target
Survivor budgets
Enter separate budgets in today's dollars for each surviving spouse. These replace the household spending strategy after the year of death and grow with inflation. Include healthcare and taxes only when your target-spend settings include them.
Legacy / heir assumptions
Assumption: automated tax moves are capped by bracket, ACA, NIIT, IRMAA, and liquidity guardrails before they are treated as recommended actions.
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Cash reserve
Sequence-risk bucket strategy
11 controls
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Monte Carlo model
Return assumptions and sampling
20 controls
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History test
How would you have done?
7 controls
Assumption: modern baseline starts in 1928. Extended source adds JST stock/bond/cash from 1872 and real estate from 1891.