🇺🇸 United States · Tax Year 2025

Capital Gains Tax Calculator

Short-term gains (held ≤1 year) are taxed as ordinary income. Long-term gains (>1 year) get preferential 0%, 15%, or 20% rates — plus the 3.8% NIIT surcharge if your income is high enough.

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Enter your details and click "Calculate" to see your estimated tax.

Short-Term vs. Long-Term — Why the Line Matters

The single biggest factor in how your capital gain is taxed isn't the size of the gain — it's how long you held the asset. Cross from exactly 365 days to 366, and the same dollar amount of gain can go from being taxed at your full ordinary rate (up to 37%) to a capped preferential rate (at most 20%, plus possible NIIT).

Holding PeriodTax Treatment
≤ 1 year (short-term)Taxed as ordinary income, at your regular marginal bracket — 10% to 37%
> 1 year (long-term)Preferential rates — 0%, 15%, or 20% depending on total taxable income

2025 Long-Term Capital Gains Brackets

RateSingleMarried Filing Jointly
0%Up to $48,350Up to $96,700
15%$48,351 – $533,400$96,701 – $600,050
20%Above $533,400Above $600,050

The 3.8% NIIT Surcharge — Now Calculated Automatically

High earners face an additional layer: the Net Investment Income Tax (NIIT), a flat 3.8% surcharge on investment income once your Modified Adjusted Gross Income crosses $200,000 (single/HOH) or $250,000 (married filing jointly). It applies to the smaller of your net investment income or the amount by which your income exceeds the threshold — and it stacks on top of whichever capital gains rate already applies. This calculator now factors NIIT in automatically when your combined income crosses the threshold.

Worked Example — With NIIT

ItemAmount
Other income (Single)$210,000
Long-term capital gain$50,000
Combined income$260,000
Long-term rate applicable15%
Capital gains tax (15% × $50,000)$7,500
Amount over $200K NIIT threshold$50,000 (fully above threshold)
NIIT (3.8% × $50,000)$1,900
Total tax on the gain$9,400

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Capital Gains Tax Rates Explained →
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Frequently Asked Questions

What's the difference between short-term and long-term capital gains?+
Short-term applies to assets held one year or less, and is taxed as ordinary income at your regular tax bracket (10-37%). Long-term applies to assets held more than one year, and gets preferential rates of 0%, 15%, or 20% depending on your total taxable income.
What is the Net Investment Income Tax (NIIT)?+
NIIT is an additional 3.8% tax on investment income (including capital gains) for taxpayers whose Modified Adjusted Gross Income exceeds $200,000 (single) or $250,000 (married filing jointly). It applies on top of whichever capital gains rate otherwise applies.
Can I pay 0% tax on long-term capital gains?+
Yes. If your total taxable income, including the gain, falls within the 0% long-term capital gains bracket (up to $48,350 single or $96,700 MFJ for 2025), the gain is taxed at 0% federally.
Does holding an asset one day longer really change the tax rate?+
Yes — crossing from exactly one year to one year and one day of holding moves a gain from short-term (ordinary rates up to 37%) to long-term (capped at 20% plus possible NIIT) treatment, which can be a significant tax difference for the exact same gain.
VERIFY

Doesn't include state tax or the standard deduction on other income. NIIT calculation is simplified (assumes all "other income" plus the gain counts toward MAGI, which may not be exactly accurate for your situation). Verify with a CPA.