Capital Gains Tax Calculator

Calculate Your Investment Tax

Estimate federal capital gains tax on investment sales for 2025. Calculate short-term and long-term capital gains tax, including Net Investment Income Tax (NIIT) on your portfolio gains.

Investment Details

Purchase Price

$0$1,000,000

Sale Price

$0$2,000,000

Cost Basis Adjustments

Improvements, fees, commissions, and other capitalized costs.

Holding Period

Short-term gains are taxed as ordinary income. Long-term gains use preferential tax rates.

Filing Status

NIIT thresholds and brackets vary by filing status.

Other Ordinary Taxable Income

W-2 wages, business income, interest, dividends, etc. (after deductions).

Tax Estimate

Effective Rate: 0.0%

Net Gain: $0

Tax Breakdown

CG Tax

NIIT

Take-Home

Quick Summary

Net Capital Gain $0

Capital Gains Tax $0

NIIT (3.8%) $0

Total Tax $0

Understanding Capital Gains Tax

Short-Term Capital Gains are profits from selling an investment you held for one year or less. These gains are taxed as ordinary income using the same federal brackets as wages and self-employment income (10%, 12%, 22%, 24%, 32%, 35%, or 37% depending on your total income and filing status). The rate depends on how much total income you have in the year.

Long-Term Capital Gains are profits from selling an investment you held for more than one year. These receive preferential tax treatment with lower rates: 0%, 15%, or 20% depending on your total taxable income and filing status. Long-term capital gains are subject to favorable tax brackets that are separate from ordinary income brackets.

How Your Ordinary Income Affects Capital Gains Tax: For long-term gains, your ordinary income (wages, business income, etc.) is stacked first in the tax calculation. Your capital gains then fill in the remaining space in each tax bracket. This means if you have high ordinary income, you'll pay more tax on your capital gains because you've already used up the lower 0% and 15% rate brackets. For short-term gains, they're added directly on top of your ordinary income and taxed at marginal rates.

Net Investment Income Tax (NIIT): If your Modified Adjusted Gross Income exceeds $200,000 (single), $250,000 (MFJ), $125,000 (MFS), or $200,000 (HOH), you must pay an additional 3.8% tax on the lesser of: (1) your net investment income (including capital gains), or (2) the amount your MAGI exceeds the threshold. This NIIT is in addition to regular capital gains tax.

2025 Long-Term Capital Gains Brackets: Single filers pay 0% on the first $48,350 of gains, 15% from $48,350 to $533,400, and 20% above $533,400. Married filing jointly pay 0% up to $96,700, 15% up to $600,050, and 20% above. These brackets adjust annually for inflation. Married filing separately and head of household have their own thresholds.

Tax Minimization Strategies: Consider timing your gains and losses strategically, holding investments longer to qualify for long-term rates, offsetting gains with capital losses, bunching income in low-income years, and reviewing your asset allocation. Consult a tax professional for personalized advice based on your specific situation and investment goals.

Common Questions

Short-term capital gains come from selling an investment held for one year or less and are taxed as ordinary income at your marginal tax rate (10% to 37% in 2025). Long-term capital gains come from selling an investment held for more than one year and receive special low rates: 0%, 15%, or 20%. Long-term rates are much more favorable, which is why investors often hold for more than a year when possible. The holding period starts the day after you purchase and ends the day you sell.

The Net Investment Income Tax (NIIT) is an additional 3.8% tax on net investment income (including capital gains, dividends, and interest) if your Modified Adjusted Gross Income exceeds certain thresholds: $200,000 for single filers, $250,000 for married filing jointly, $125,000 for married filing separately, and $200,000 for head of household. The NIIT applies to the lesser of your net investment income or the amount your MAGI exceeds the threshold. This is in addition to regular capital gains tax.

For long-term capital gains, your ordinary income is "stacked" first in the tax brackets, and your gains fill the remaining space. If you already have high ordinary income, you'll pay a higher tax rate on your capital gains because you've used up the lower rate brackets. For example, if you're single with $100,000 of ordinary income, your long-term gains start at the 15% bracket rather than the 0% bracket. This is why timing income and gains strategically can reduce your overall tax bill.

Yes, you can use capital losses to offset capital gains, which can significantly reduce your tax liability. If losses exceed gains, you can deduct up to $3,000 of net losses against ordinary income in a single year. Any excess losses can be carried forward indefinitely to offset future gains or income. This is called "tax-loss harvesting" and is a common strategy for managing investment tax liability over time.

For 2025, the long-term capital gains brackets are: Single: 0% on the first $48,350 of gains, 15% from $48,350 to $533,400, and 20% above. Married filing jointly: 0% on the first $96,700, 15% from $96,700 to $600,050, and 20% above. Married filing separately: 0% on the first $48,350, 15% from $48,350 to $300,000, and 20% above. Head of household: 0% on the first $64,750, 15% from $64,750 to $566,700, and 20% above. These thresholds are indexed for inflation and may adjust slightly each year.

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Tax Disclaimer

This calculator provides estimates for educational purposes and should not replace professional tax advice. Capital gains tax is complex and depends on many factors including your total income, filing status, holding period, and state taxes. Wash sales, qualified dividend income, and collectibles have special rules. Consult a qualified tax professional or CPA before making investment decisions or filing your tax return. The IRS provides official guidance at irs.gov.