A fast, reliable calculation engine for Claude, ChatGPT, and other MCP-compatible AI assistants — sync balances from a Monarch export (no credentials), goal planning, IRS tax tables for 2024–2026, Social Security optimization, and projections you can dial from fast formulas to full Monte Carlo. Computed, never guessed.
01 The Problem
Large language models are great at conversation. They are the wrong tool for tax brackets, contribution limits, and projection math. Ask "Can I retire at 60?" and you get plausible text — not a computed answer with the IRS tables, the contribution limits, and the scenarios actually run.
FinPlanTools fixes that. Your AI assistant calls FinPlanTools, gets exact numbers back, and answers you with math instead of narrative.
02 How It Works
Each capability is a typed MCP tool. Your assistant picks the right one, fills in your data, and gets exact numbers back. No prompt engineering. No screen scraping.
One interface, two methods.
Fast formula-based projections by default. Full Monte Carlo when path dependency or precision demands it — same tool call, you pick the method.
Explore 02Federal, capital gains, AMT, and NY state.
IRS tables for 2024–2026 across all filing statuses. NY state income tax, capital gains rates, AMT, after-tax projection adjustments, and safe-harbor estimates.
Explore 03Every type, modeled.
401(k), traditional and Roth IRA, HSA, taxable brokerage, real estate — each with current contribution limits, asset-class rules, and tax treatment.
Explore 04Claiming math, end to end.
PIA from salary history, benefits at every claiming age 62–70, breakeven analysis, spousal and survivor benefits, and the earnings test.
Explore 05Required distributions, calculated.
Year-by-year RMD schedules per account, aggregation across IRAs, uniform and single-life tables, and shortfall penalties under SECURE 2.0.
Explore 06Probability-targeted.
Set goals by success probability, not just dollar amount. Tax-advantaged routing, target-date flexibility, real-time progress.
Explore 07Returns, volatility, glide paths.
Capital market assumptions you can override. Per-account allocations, expected return + volatility math, age-based glide paths.
Explore 08Full amortization, on demand.
Monthly payments, full amortization schedules, principal-vs-interest splits at any point in the term — for any rate, term, or balance.
Explore 09Client-ready visualizations.
Projection fan charts, glide paths, scenario comparisons, allocation breakdowns, amortization curves. Renders client-side from typed chart data.
Explore 10Point-in-time, diffable, auditable.
Immutable, versioned records of your full financial state, captured at a point in time. Diff two snapshots to see exactly what changed — balances, contributions, assumptions — between check-ins.
Explore 11Income, expenses, cash flow.
Income streams and recurring expenses roll up into a household cash-flow timeline. Surplus and deficit, month by month — the inputs that projections and goals build on.
ExploreModel an ISO exercise with the AMT impact in the exercise year, cash needed at strike, qualifying vs disqualifying disposition outcomes, and the capital-gains math once the holding period clears. Compare scenarios side-by-side in a single conversation.
Explore equity toolsISO exercise
Strike × shares, FMV bargain element, cash required at exercise.
AMT impact
AMT in the exercise year, regular-tax delta, and credit recovery over future years.
Qualifying disposition
Long-term capital gain after 1yr from exercise, 2yr from grant.
Disqualifying disposition
Ordinary income on the bargain element, capital gain on the rest.
03 Composability
Most planning tools show you the views their designers chose to build. You're stuck with someone else's dashboard. FinPlanTools exposes the underlying math as composable tools, so your assistant can combine them on the fly — answering questions no one ever designed a screen for.
“What if I take a year off and use the low-income year to harvest capital gains?”
Composes
“What will having a kid in three years do to our plan?”
Composes
“Should I convert to Roth now, before RMDs push me into a higher bracket?”
Composes
“Can I drop to part-time at 55 and still claim Social Security at 67?”
Composes
“Am I on track for the house down payment if I redirect this year's bonus to it?”
Composes
Same building blocks, endless questions. If you can phrase it, your assistant can route it to real math and hand you a number you can show your work on — and compare it side-by-side against a different scenario in the same conversation.
04 Accounts & Goals
FinPlanTools models every account you actually hold and every goal you're saving toward — then links the two, so funding and progress track themselves.
Nineteen account types, each carrying its real rules — contribution limits, employer-match formulas and vesting, RMDs, asset allocation, and tax treatment. Not a generic balance field.
Retirement
Health & education
Taxable & cash
Property
Set a goal by the confidence you want to hit it — 90% sure, not just a dollar figure — with flexible target dates and inflation-aware targets. Earmark accounts to it and the funded amount is derived from their balances automatically: no manual updates, no double-counting.
House down payment
68%
$120,000 by 2028 · 90% confidence
$81,600 of $120,000 funded
Earmarked accounts
As those balances move, the goal re-tracks — progress, remaining amount, and the projection to your target date update with it. Stack goals with preconditions, too: fund the 529 only once the emergency fund clears 80%.
05 Why Trust It
Run it fully local and your state stays plain JSON on your own disk — nothing leaves the machine. Or go hosted for zero-install setup — anything you send lives for at most an hour, then it's gone. Here's exactly what we hold, and for how long.
Money is tracked in cents. Tax brackets come from published IRS documents. Nothing is rounded, estimated, or scraped from a blog post.
Reproducible. Auditable. Run a projection today and a year from now with the same data — identical results. Every projection can be pinned to a dated snapshot you can diff later.
06 Setup
FinPlanTools speaks the Model Context Protocol, so any MCP-compatible assistant can use the same tools. Connect in a few minutes.
Install the plugin in two commands. FinPlanTools loads as MCP tools plus a set of finplan-prefixed slash commands. OAuth handles auth automatically.
Guided workflows like /finplan:checkup and /finplan:projection-dashboard ship alongside them — see the full skills reference.
$ claude plugin marketplace add bestdan/finplan-plugin $ claude plugin install finplan@finplan-plugin // then in any Claude Code session: > /finplan:setup
Closing
Pick your assistant, paste a config, and ask a question with an answer you can show.