Estimate your federal tax on capital gains for tax year 2025, including the difference between short-term gains (generally taxed like ordinary income) and long-term gains (often 0% / 15% / 20%). The IRS explains the basics of capital gains and holding periods in Topic 409, and the additional Net Investment Income Tax (NIIT) is reported on Form 8960.
This tool estimates your federal tax on a single capital gain by applying the same rate logic used in your current 2025 calculator implementation :contentReference[oaicite:1]{index=1}: choose a holding period (short-term or long-term), enter ordinary income, and enter a gain (or let proceeds minus basis compute it). For IRS definitions of “basis” and how gains are computed on asset sales, see IRS Topic 703 (Basis of Assets) and IRS Topic 409.
If you want an easy, reputable overview of short-term vs long-term treatment (and why holding period matters), Fidelity’s explainer is a useful complement: capital gains tax rates and basics.
Enter a gain directly, or compute it as proceeds minus basis. IRS basis concepts are summarized in Topic 703.
Short-term gains are treated like ordinary income, while long-term gains may qualify for preferential rates. See IRS Topic 409.
If selected, the calculator estimates the 3.8% NIIT on the applicable base using a simplified threshold approach aligned to the logic in your existing build :contentReference[oaicite:3]{index=3}. NIIT is filed on Form 8960.
The output shows estimated total tax and net proceeds from the gain amount, plus an effective rate on the gain for quick comparison.
Short-term gains (assets held one year or less) are generally taxed like ordinary income, while long-term gains (held more than one year) may qualify for preferential rates. The IRS overview is in Topic 409, and Fidelity provides a practical explanation here: capital gains tax rates and basics.
A basic gain is sale proceeds minus your basis (often what you paid plus certain costs). The IRS discusses basis concepts in Topic 703.
NIIT is an additional 3.8% tax on certain net investment income for some higher-income taxpayers and is filed on IRS Form 8960. This calculator provides a simplified estimate when you enable the NIIT option.
No. This tool estimates federal tax only. State rules vary widely; treat state impact as a separate calculation.
No. Some gains can be subject to special federal rates or rules (for example, certain real estate depreciation recapture or collectibles). This calculator is intended for the most common “standard” capital gain scenarios and keeps the decision focused.
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