# FIREproof The cFIREsim author's second simulator, with the taxes and accounts the first one lacks. *https://stockmarketstack.com/tools/fireproof · Retirement & FIRE Calculators* ## Facts ### At a glance | Field | Value | | --- | --- | | Vendor | Lauren Boland | | Category | Retirement & FIRE Calculators | | Job | retirement | | Website | https://fireproofme.com | | Pricing model | subscription | | Free tier | true | | Open source | false | | Licence | none | | Self-hosted | false | | Tested hands-on | false | | Last updated | 2026-09-14 | ### Pricing | Tier | USD | Period | | --- | --- | --- | | Basic | 0 USD | month | | Pro | 10 USD | month | | Financial Planner | 50 USD | month | ### Coverage | Field | Value | | --- | --- | | Asset classes | stocks, bonds, commodities, real_estate | | Markets | us, ca, uk, eu | | Works outside the US | true | | Data latency | none | | Platforms | web | | AI features | none | ### Interfaces | Field | Value | | --- | --- | | API | false | | Webhooks | false | | Scripting | none | | Python | false | | Spreadsheet add-in | false | | MCP server | false | | Export | xlsx | ### Capabilities Yes: backtesting No: charting, screening, scanning, automation, live_trading, paper_trading, portfolio_tracking, broker_import, tax_reporting, alerts, news, options_analysis *Verified: pricing 2026-09-14; capabilities 2026-09-14; coverage 2026-09-14.* ## What it is FIREproof is the second retirement simulator from the author of cFIREsim, and it exists to answer the question cFIREsim explicitly refuses: what the tax code does to the plan. The method is the same — enter a plan, replay it against every overlapping window of market history, count how many survived — but the pot of money is no longer undifferentiated. Accounts have types, withdrawals have an order, and every dollar that moves is run through brackets, capital gains with cost basis, FICA, RMDs and 72(t). Inputs are an eight-step stepper: People, Accounts, Income, Expenses, Real Estate, Tax Strategy, Cash Flow, Parameters. Account types run from 401(k), Roth IRA, brokerage, HSA and Solo 401(k) to inherited IRAs with their own ten-year SECURE Act clocks. On top sit the pieces that decide a US early retirement — a Roth conversion optimiser that fills a bracket you name, ACA premium tax credits projected by ZIP with the subsidy cliff flagged, Medicare IRMAA tiers, a NIIT threshold cap, and a FAFSA optimiser that routes withdrawals around a child's base years. Spending can follow Guyton-Klinger, VPW, CAPE, Hebeler autopilot, or a risk-based guardrail that re-solves each check-in year against a success rate you pick. Real estate is modelled properly: mortgages year by year, appreciation, rental cash flow with depreciation, and 1031 exchanges. Development is unusually visible. The public changelog carries 1.9.0 on 12 September 2026, two days before this card was written, and sixty-four releases in the seven months behind it. ## Pricing Basic is free and holds one saved simulation. Pro is 10 dollars a month month-to-month, or 89 a year. A Financial Planner plan is 50 a month or 399 a year and includes 20 active client seats, with 2 dollars a month for each additional claimed client; unclaimed prospects are free. Read the feature table before assuming the free tier is a small version of the paid one. Fourteen of its sixteen rows are Pro-only, and they are the rows that describe the product — withdrawal order, the TIPS ladder, Roth conversions and 72(t), bracket-filling withdrawals, ACA optimisation, the bucket strategy, Monte Carlo custom assets, comparing two simulations, uploading a dataset, and year-by-year account statements among them. Besides the simulator, Basic shares exactly one row with Pro: Discord access. ## Data & coverage Eleven named series, each published by the app with its source and year range. The two defaults are Robert Shiller's S&P composite and the US 10-year Treasury, both starting in 1871 and carrying a 2026 entry. Most optional sleeves are shorter: Ken French's factor portfolios from 1927, NAREIT's REIT index from 1972, five-year Treasuries from 1962, Developed International from 1991, CRSP total market via VTSAX from 2001, plus synthetic TIPS-real and aggregate-bond series derived from the Treasury yield. Gold and cash are separate asset types, and Pro can upload a custom series. The substitution rule matters more than the list. Every optional sleeve names a proxy and, before its own first year, runs that proxy instead — usually the S&P composite, and the 10-year Treasury for the bond sleeves. The app does say so where you pick the sleeve, in amber under the asset row ("Pre-1991 → S&P500 Composite"), and a "use only cycles with full data for every series" switch turns the substitution off. What it does not do is repeat any of that in the results: a portfolio with an International Developed sleeve backtested over the 1929 cycle is running US large-cap returns under an international label, and the Proof view never mentions it. ## Integrations None yet. There is no public API, no broker or bank connection and no MCP server, so every balance is typed in by hand and retyped when it moves; read-only account sync is a roadmap item. What comes out is a two-sheet Excel workbook covering every cycle and every year, on Pro, and a share link that publishes a read-only snapshot of a plan with names and account labels redacted by default. ## Limitations - **The free tier is a demonstration, not a tool.** One saved simulation, and none of the tax modelling. Budget 10 dollars a month or use the predecessor. - **Optional sleeves substitute another series before their start year** — flagged under the asset row where you choose it, never again in the results. The honest history for anything but US large-cap and Treasuries is far shorter than 1871. - **Overlapping cycles are not independent trials.** A 35-year plan runs 122 windows that share most of their years, so a success rate is not a probability. - **Monte Carlo runs per asset, not across the portfolio.** Correlated whole-portfolio returns are on the vendor's own roadmap, which means success rates from that mode ignore diversification. - **Non-US support stops at the tax brackets and the account wrappers.** The healthcare, Medicare and required-distribution modelling is US statute and does not travel. - **Closed source, one developer, two products.** There is no repository and nothing to self-host. The author has said plainly, on a public forum in August 2026, that focusing on FIREproof is why cFIREsim's market data sat unrefreshed for some twenty months — which is the honest shape of the key-person risk in paying for this one. ## Alternatives [cFIREsim](https://stockmarketstack.com/tools/cfiresim) is the same author's earlier and free tool, and remains the right answer if taxes are not the question. [FI Calc](https://stockmarketstack.com/tools/ficalc) covers withdrawal strategies against the same historical cycles, free and without an account. [Boldin](https://stockmarketstack.com/tools/boldin) and [ProjectionLab](https://stockmarketstack.com/tools/projectionlab) are the closest paid competitors for a whole-life plan with US tax modelling, both sold as annual plans rather than by the month. [Portfolio Visualizer](https://stockmarketstack.com/tools/portfolio-visualizer) is the one to reach for if the real question is the allocation rather than the drawdown. ## FAQ ### Is FIREproof the reason cFIREsim stopped getting updates? For the market data, yes, and the author said so herself. Asked on the Bogleheads forum why cFIREsim still advertised data from November 2024, she replied on 5 August 2026 — "And yeah, I haven't updated the data on cFIREsim in a while because I've been focusing on FIREproof. When I get back from this work trip, I'll update to current data." She then did, and the site now advertises data through 1 August 2026. So the neglect was real and FIREproof caused it, but cFIREsim is not abandoned and she has never said it is — her own banner there calls FIREproof its "sister site" rather than its successor. What stays unexplained is the feature side, where cFIREsim's changelog has not moved since September 2022. ### What does the free tier actually get you? One saved simulation, a Discord invite, and the full historical engine. What it does not get you is the tax machinery that is the whole reason to prefer FIREproof over its free predecessor — Roth conversions, 72(t), bracket-filling withdrawals, ACA subsidy optimisation, the TIPS ladder, the bucket strategy, comparing two simulations and the spreadsheet export are all Pro. A sample scenario runs at /try with no account at all. ### How far back does the market data go, and is it current? 156 contiguous annual years, 1871 through 2026, confirmed on 14 September 2026 by running a one-year simulation and counting the cycles it returned. That applies to the two default sleeves — Shiller's S&P composite and the 10-year Treasury. Most optional sleeves are shorter and several stop at 2025. ### Does it work outside the United States? Partly. Setting the tax jurisdiction to Canada, the United Kingdom or Spain returns that country's real brackets — Canada's 16,452 dollar basic personal amount, the UK's 12,570 pound allowance and 20/40/45 bands, Spain's 19/24/30/37/45/47 — and surfaces TFSA and RRSP, ISA and SIPP, or Plan de Pensiones as account types. Everything built on US statute stays US-only, because Medicare IRMAA, ACA premium tax credits, RMDs and 72(t) have no equivalent to map onto. ## Also from Lauren Boland - [cFIREsim](https://stockmarketstack.com/tools/cfiresim.md) ## Also worth comparing - [Boldin](https://stockmarketstack.com/tools/boldin.md) — A year-by-year US retirement model — accounts, taxes, Social Security, Medicare, housing. - [ProjectionLab](https://stockmarketstack.com/tools/projectionlab.md) — Model a whole financial life as milestones and cash flows, then run it against history. - [FI Calc](https://stockmarketstack.com/tools/ficalc.md) — Twelve withdrawal strategies replayed against every US market cycle since 1871. - [Portfolio Charts](https://stockmarketstack.com/tools/portfolio-charts.md) — Any asset allocation, charted since 1970 in twelve countries' currencies and inflation. - [Portfolio Visualizer](https://stockmarketstack.com/tools/portfolio-visualizer.md) — Backtest an asset mix to 1972, run Monte Carlo, regress it on Fama-French factors. - [testfolio](https://stockmarketstack.com/tools/testfolio.md) — Backtest an allocation on daily data to 1885, using simulated pre-inception fund series. ## Named as a replacement for - [Portfolio Visualizer](https://stockmarketstack.com/alternatives/portfolio-visualizer.md)