Capital Gains Tax Calculator
See exactly what you'd owe on your sale — federal, state, and NIIT — and which tax-deferral strategy fits your gain.
Your sale details
Showing a sample scenario — replace with your own values to see your numbers. Updates live as you type. We don't store anything.
If you sell traditionally
$320,108
in capital gains tax owed at closing.
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Structured Installment Sale (Iron Gate Holdings) — Sub-$1M in capital gains — Iron Gate Holdings SIS is the right fit.
537 Installment Sale Trust
Built for $1M+ capital gains
Structured Installment Sale
Built for sub-$1M capital gains · Iron Gate Holdings
Estimates use 2025 IRS brackets and the same engine that powers our gated estimators. For a personalized report with payment schedules and 50-year projections, run the full estimator for your recommended product.
Methodology
How the math works
We use the same IRS brackets and state-tax tables that power our full Revenue Estimator and Pro Forma Report tools (2025, IRS Rev. Proc. 2024-40). The calculator includes:
- ✓Federal long-term capital gains: 0% / 15% / 20% brackets
- ✓Top marginal state rate for your state of residence
- ✓Net Investment Income Tax (NIIT) at 3.8% above thresholds
- ✓§121 exclusion auto-applied for personal residences ($250K single / $500K MFJ)
- ✓Sales-expense deduction by asset class (commission, fees, closing costs)
- ✓Boot-tax handling when debt exceeds cost basis
For state-by-state CGT rates, see our capital gains tax by state reference.