At a glance
Killion is planning and simulation software with read-only account linking. Boldin is described below in its own terms. Where a figure is quoted it comes from the vendor's published pricing and was checked on the date shown.
| Killion | Boldin | |
|---|---|---|
| Individual price | $14/mo, or $11/mo billed annually ($132/yr). Max tier $24/mo or $19/mo annually. | Free Basic plan. PlannerPlus $144/yr, rising to $168/yr ($14/mo billed annually) for new subscribers on October 15, 2026; existing subscribers keep the price they signed up at. |
| Free entry point | Live no-signup Monte Carlo demo on a fictional household, plus a 5-day free trial of the full product. Card required for the trial; no charge until it ends. | Free Basic plan with a reduced feature set, and a 14-day PlannerPlus trial. |
| Account linking | Read-only brokerage and crypto linking via SnapTrade. Cash and bank balances are entered manually while automatic bank linking moves to a new provider. | Account linking for net worth and balances. |
| Tax modeling | Opt-in tax estimates on paid plans: federal and state income tax on every simulated year, RMDs, Roth conversions with a rule-by-rule comparison, Social Security taxation, IRMAA and ACA credits. Estimates for planning, not tax advice. | Roth conversion modeling, state and federal tax projections, and tax-bracket-aware planning. This is the product’s center of gravity. |
| Simulation method | 1,000-path regime-switching Monte Carlo with fixed seeds, so a run reproduces. | Monte Carlo with optimistic/pessimistic assumption sets. |
| Historical backtesting | Historical backtesting against real market data going back to 1928. | Not the primary method. |
| Withdrawal rules | Seven named rules in the planner: Guyton-Klinger guardrails, Vanguard dynamic spending, constant dollar (the 4% rule), percent of balance, VPW, a ratchet, and floor and ceiling. Free calculators cover nine published rules. | Withdrawal-order and spending strategies with tax awareness. |
| Human advice | None. Killion is software; it is not a registered investment adviser. | Paid sessions with financial advisers are available. |
Boldin details checked on against the Boldin pricing page. Vendors change prices; verify before deciding.
Where Boldin is still ahead
Boldin’s tax tools are mature: which account to draw from, what a Roth conversion in a low-income year does to lifetime tax, and where the IRMAA cliffs sit, refined over years and with an adviser a click away. For someone five years from retirement, those decisions are often worth more than a better return model.
Killion added tax estimates in October 2026. Turn tax on in a paid plan and every simulated year estimates federal and state income tax, RMDs, Roth conversions (with conversion rules compared side by side), Social Security taxation, IRMAA and ACA credits. It is newer than Boldin’s, opt-in, and an estimate for planning, not tax advice.
Where Killion is ahead
Killion’s engine is the product rather than a feature of it. Returns come from a regime-switching model in which bad years cluster, runs are seeded so results reproduce, and the same plan can be backtested against every starting year since 1928 rather than only sampled.
That matters most for the questions Monte Carlo is actually good at: how much sequence-of-returns risk you are carrying, how much a flexible spending rule buys you compared with a rigid one, and how wide the range of outcomes really is around the median you were quoted.
Killion also ships seven named withdrawal rules, including Guyton-Klinger guardrails, Vanguard dynamic spending and VPW, and benchmarks them against each other on identical simulated markets.
They are not mutually exclusive
These two products answer different halves of the same problem, and plenty of people run both: Boldin for its guided tax and Social Security tools, Killion for the simulation, the stress tests and tax across a range of markets. At $132 and $168 a year that is a real cost, but it is a fraction of one year of a 1% assets-under-management fee on a $500,000 portfolio.
Which one to choose
Choose Killion if
- You want to stress-test the plan itself: what a crash in year one of retirement does, how a guardrail rule changes the ruin rate.
- You want every figure reproducible, with the engine documented rather than described.
- You want tax estimated across 1,000 simulated markets, not one straight-line projection.
- You want an AI assistant with your real holdings in context.
Choose Boldin if
- You are within a decade of retiring and want a guided Roth conversion explorer refined over years.
- You want Social Security claiming analysis in the same tool.
- You want the option to buy time with a human adviser inside the same product.
- You want a free tier to start on.