The most comprehensive DIY tax planner.The depth of tax filing software — without the complexity.
Enter your key numbers in minutes to model any tax scenario across federal and all 50 states.
Free to use·No credit card required·Federal + All 50 states
The Tax Engine
Powered by PolicyEngine, the modern standard for US tax simulation.
TaxVant is built on PolicyEngine , founded in 2020. The calculations are continuously validated against TAXSIM from the National Bureau of Economic Research (NBER), matching federal and state calculations to the penny, and PolicyEngine is slated to succeed TAXSIM from 2026 onwards.
Our tax engine is transparent and open source. Audit our code on GitHub
The Tax Planning Blindspot
Why planning by tax brackets is a costly illusion.
Most DIYers and advisors plan around statutory federal brackets (12%, 22%, 24%) or static income thresholds. But our tax code is built in layers. Overlapping phase-outs, income stacking, and cliff edges mean your true marginal tax rate is rarely what the IRS table says.
TaxVant eliminates the blindspots. Ranger charts your exact marginal rate curve, while Explain this uses AI to educate you on why the curve behaves the way it does. It isolates the exact statutory rules affecting your household, so you understand your situation without wading through tax code that doesn't apply to you.
Explore real scenarios below to see how these blindspots play out in practice:
The Roth Conversion & Capital Gains Trap
Nominal Bracket: 21.3% → Actual Marginal Rate: 36.3%
See how Roth Conversion lifts the floor beneath long-term capital gains, pushing gains from the 0% to the 15% tier. Discover the statutory mechanism behind the stealth surcharge.
The Long-Term Capital Gains & SALT Phaseout Trap
Expected Rate: 28.1% → Effective Marginal Rate: 38.7%
A high-earning married couple realizing capital gains triggers a 10% stealth ordinary tax hike. Discover how the new 2026 statutory SALT cap phaseout penalizes capital gains.
The Social Security Tax Torpedo & Senior Deduction Trap
Expected Rate: 17.4% → Peak Marginal Rate: 49.5% + IRMAA
A retired senior in Minnesota with $35k in Social Security takes modest IRA distributions, triggering the 1.85x federal tax torpedo, state subtraction phaseout, and Medicare IRMAA cliffs.
Investment Income Tax Drag & Asset Location in NYC
Comparing Marginal Rates from 27.8% to 46.3%
How high earners in New York City face dramatically different marginal tax drag across Treasuries, Qualified Dividends, REITs, and Corporate Bonds, modeled down to NYC local income taxes.
The ACA Subsidy Cliff & the 0% Capital Gains Trap
Expected Rate: 0% Fed → Actual Marginal Rate: 16% to 11,000% Cliff
Most ACA enrollees know subsidies phase out, but struggle to quantify it as a tax rate. See how pre-Medicare retirees face a 16% to 23% baseline drag and an 11,000% cliff on Form 8962.
Household Strategy Comparison
Side-by-Side Multi-Scenario Analysis
Compare a baseline salaried household against pre-tax 401(k) contributions and Head of Household filing status. Inspect every federal and state line item side by side.