Retirement tax modelers, startup equity simulators, mortgage and real estate economics, and compensation planning — each one showing its formulas and citing the rule it is calibrated against.
Calibrated against IRS statutory rules, SECURE 2.0, HMRC tax bands, and institutional financial models.
Backdoor Roth IRA pro-rata rules, Solo 401(k) vs SEP IRA limits, 401(k) employer match true-ups, HSA triple-tax growth, and 529 state tax benefits.
Mortgage extra principal vs S&P 500, loan recast vs refinance math, discount-point breakeven, home affordability, BRRRR underwriting, and rent-hike vs moving costs.
Startup ISO vs NSO stock options with Form 6251 AMT liability, RSU withholding shortfalls, Tech Offer total-comp comparison, W-2 vs 1099 vs C2C, and freelance rate pricing.
HDHP + HSA vs traditional PPO plan comparison with employer seed contributions, the HSA triple-tax deduction, and the long-run “stealth IRA” reimbursement strategy.
Direct client-side execution with step-by-step mathematical breakdowns and execution checklists.
Model clean $0 pro-rata conversions for high earners and calculate Form 8606 reverse rollover tax shielding.
Evaluate the true opportunity cost of prepaying low vs high-rate mortgages against equity index compounding.
Simulate Form 6251 Alternative Minimum Tax on early exercise spread gains vs secondary liquidity exits.
Offset capital gains, claim the $3,000 ordinary income write-off, and rotate ETF proxies without tripping the wash-sale rule.
Calculate 6,000+ lbs GVWR first-year bonus depreciation deductions and recapture rules for business owners.
Model rehab budgets, 75% ARV cash-out refinances, capital recapture, DSCR coverage, and cash-on-cash ROI.
Model the gap between the statutory 22% supplemental withholding rate and your real marginal rate before Form 2210 penalties land.
Calculate exact dollar-for-dollar employer match returns, vesting schedules, and true paycheck take-home impact.
Calculate break-even timeline on 25bps–100bps rate cuts factoring closing points and amortized interest savings.
Weigh payroll premium savings and employer HSA seeds against deductibles and out-of-pocket maximums across three spending scenarios.
We computed 500 W-2 × ISO spread scenarios under 2025 IRS AMT parameters. Find your exact cliff—and the phaseout trap that imposes a hidden 35% marginal rate on illiquid startup equity.
Browse every calculator in one place — retirement and tax planning, mortgages and real estate, startup equity and compensation, and health-plan comparison.
A transparent overview of how our calculators and simulation models are engineered, verified, and run with zero personal data retention.
Every calculation occurs entirely within your browser's local memory using pure client-side JavaScript. When you calculate tax liability, debt amortization, or option spreads, your financial inputs never leave your browser.
Our tax and wealth models are calibrated directly to public statutory frameworks: the Internal Revenue Code (Sections 179, 1202, 415(c)), SECURE 2.0 distribution rules, and published IRS withholding tables. Each calculator links the source it relies on.
Every calculator is checked by an automated regression suite that re-runs its worked examples against standard financial formulas on each change, so published numbers stay reproducible.