Capital Gains Tax Calculator
See exactly how your investment gains are taxed — compare long-term vs short-term rates, check if the 3.8% NIIT applies, and discover how much you save by holding over one year.
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Investment tax demystified
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Avg. LTCG Savings
By holding over 1 year
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Capital Gains Tax Calculator
Long-term vs short-term with NIIT analysis
Tax on Gains
$7,500
Effective Rate
15.0%
After Tax
$42,500
Disclaimer: This calculator provides estimates for educational purposes only. Based on 2025 federal capital gains rates from IRS Revenue Procedure 2024-40. Consult with a qualified CPA for personalized tax advice.
How Capital Gains Tax Works in 2025
When you sell an investment for more than you paid, the profit is a capital gain. How much tax you owe depends on two things: how long you held the asset and your total income level.
The "Stacking" Effect
Capital gains are "stacked" on top of your ordinary income. The IRS first taxes your wages, salary, and other ordinary income. Then your capital gains fill the remaining room in each bracket. This means someone with $40K in salary and $20K in gains pays a different rate than someone with $200K in salary and the same $20K in gains — even though the gain amount is identical.
0%, 15%, and 20% — The Three Long-Term Rates
For 2025, long-term capital gains (assets held over one year) are taxed at preferential rates. Single filers pay 0% on gains up to $48,350 of total taxable income, 15% up to $533,400, and 20% above that. Married filing jointly thresholds are roughly double.
The 3.8% NIIT Surcharge
High earners face an additional Net Investment Income Tax (NIIT) of 3.8% on investment income when MAGI exceeds $200,000 (single) or $250,000 (married filing jointly). This effectively makes the top long-term rate 23.8% (20% + 3.8%) for the highest earners.
Frequently Asked Questions
What is the difference between short-term and long-term capital gains?
Short-term capital gains (assets held 1 year or less) are taxed as ordinary income at your marginal tax rate. Long-term capital gains (assets held more than 1 year) receive preferential rates of 0%, 15%, or 20% depending on your income level.
What is the Net Investment Income Tax (NIIT)?
The NIIT is an additional 3.8% tax on investment income (including capital gains) for taxpayers with modified adjusted gross income above $200,000 (single) or $250,000 (married filing jointly). It applies to the lesser of your net investment income or the amount your MAGI exceeds the threshold.
How are capital gains "stacked" on top of ordinary income?
The IRS taxes ordinary income first, then capital gains are "stacked" on top. This means your capital gains rate depends on your total taxable income. If ordinary income already fills the 0% bracket, your gains start in the 15% bracket.
Can I offset capital gains with capital losses?
Yes. Capital losses offset capital gains dollar-for-dollar. If your losses exceed gains, you can deduct up to $3,000 of net losses against ordinary income per year, carrying excess losses forward to future years.
How does the holding period affect my tax bill?
Holding an asset for more than one year before selling qualifies it for long-term capital gains rates (0%, 15%, or 20%), which are significantly lower than ordinary income rates (10% to 37%). This difference can save thousands — use the calculator above to see the exact savings.
Want to minimize your capital gains tax?
This calculator shows your current tax picture. A CPA can identify strategies like tax-loss harvesting, charitable giving of appreciated assets, and timing sales to minimize your total bill.
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