Federal Tax · 2025
Capital Gains Tax Calculator
Enter your ordinary income and capital gains to see exactly how the 2025 federal tax rules apply — short-term gains taxed as ordinary income, long-term gains at 0%/15%/20% rates, the stacking effect of your income on those rates, and the 3.8% Net Investment Income Tax (NIIT) at high incomes.
Your information
Wages, salary, interest, ordinary dividends
Assets held 1 year or less — taxed as ordinary income
Assets held more than 1 year — preferential 0%/15%/20% rates
Informational only — not professional tax advice.
Enter your income and gains to see your capital gains tax breakdown — long-term rates, stacking effect, and NIIT all shown.
Methodology
Short-term capital gains
Short-term gains (assets held ≤ 1 year) are added to ordinary income and taxed at the same progressive bracket rates as wages. The combined amount is reduced by your deduction (standard or itemized) to arrive at taxable ordinary income. The 2025 standard deductions are $15,000 (single/MFS), $30,000 (MFJ), and $22,500 (HOH), per IRS Rev. Proc. 2024-61.
Long-term capital gains — the stacking rule
Long-term gains (assets held > 1 year) are taxed at preferential rates: 0%, 15%, or 20%. The applicable rate depends on total taxable income, not just the gains themselves. Gains are conceptually "stacked" on top of ordinary taxable income: the rate that applies to each dollar of gain is the long-term rate for the total income level at that point.
Taxable ordinary income = max(0, ordinary income + short-term gains − deduction) LTCG tax rate bracket = determined by taxable ordinary income + long-term gains position Long-term gains tax = Σ (gains in each LTCG bracket × bracket rate)
The 2025 long-term capital gains thresholds from IRS Rev. Proc. 2024-61:
| Rate | Single | MFJ | MFS | HOH |
|---|---|---|---|---|
| 0% | Up to $48,350 | Up to $96,700 | Up to $48,350 | Up to $64,750 |
| 15% | $48,350 – $533,400 | $96,700 – $600,050 | $48,350 – $300,000 | $64,750 – $566,700 |
| 20% | Over $533,400 | Over $600,050 | Over $300,000 | Over $566,700 |
Net Investment Income Tax (NIIT)
The NIIT is a 3.8% surtax imposed by IRC §1411 (see also Form 8960 instructions) on the lesser of: (a) net investment income, or (b) MAGI in excess of the threshold. This calculator uses a simplified MAGI equal to total gross income (ordinary + short-term gains + long-term gains), without above-the-line adjustments. NIIT thresholds ($200,000 single, $250,000 MFJ, $125,000 MFS, $200,000 HOH) are not indexed for inflation and have been fixed since 2013.
NIIT = 3.8% × min(net investment income, max(0, MAGI − threshold))
Marginal vs. effective rate on gains
The "effective rate on long-term gains" shown by this calculator is the total capital gains tax (LTCG tax + NIIT) divided by your long-term gain amount. Because the stacking effect may split gains across multiple rate brackets, this effective rate will often be between two nominal rates (e.g., between 0% and 15%).
Stated assumptions and limitations
- Ordinary income brackets only. This calculator applies the 2025 progressive income tax brackets to ordinary income and short-term gains. It does not model the Alternative Minimum Tax (AMT), qualified dividends (which follow the same rate table as long-term gains), or any tax credits.
- Simplified MAGI for NIIT. MAGI is approximated as total gross income. Real MAGI may differ due to above-the-line deductions (IRA contributions, student loan interest, self-employment tax deduction, etc.).
- Net investment income is capital gains only. Real NII can include interest, dividends, passive income, and rental income. This calculator scopes NII to short-term and long-term capital gains only.
- No installment sales, wash sales, or loss carryovers. This tool treats entered gains as net capital gains after any loss netting. Carryforward losses from prior years are not modeled.
- Federal only. Most states tax capital gains — many at ordinary income rates with no preferential long-term treatment.
Last reviewed: January 2025. Rates reviewed annually after IRS publishes updated Rev. Proc. (typically November). NIIT thresholds are statutory and not adjusted for inflation.
Frequently asked questions
What is the difference between short-term and long-term capital gains?
A short-term capital gain comes from selling an asset you held for one year or less. It is taxed as ordinary income — at the same rates as your wages or salary (10%, 12%, 22%, 24%, 32%, 35%, or 37% depending on your total income). A long-term capital gain comes from selling an asset held for more than one year. It receives preferential rates: 0%, 15%, or 20% in 2025, depending on your total taxable income. The holding period cutoff is exact: if you bought on January 15, 2024, the one-year mark is January 16, 2025 — one day matters.
How does ordinary income affect my long-term capital gains rate?
Long-term capital gains are 'stacked' on top of your ordinary taxable income when determining which rate applies. The 0%, 15%, and 20% brackets are thresholds based on total taxable income — not just your gains. For a single filer in 2025, the 0% rate applies to long-term gains that fall within the first $48,350 of total taxable income. If you have $40,000 in ordinary income, only $8,350 in long-term gains fall in the 0% bracket; the rest are taxed at 15%. This stacking effect means a higher ordinary income pushes your long-term gains into higher rate tiers.
What is the Net Investment Income Tax (NIIT) and when does it apply?
The Net Investment Income Tax (NIIT) is a 3.8% surtax on investment income for higher-income taxpayers, enacted by the Affordable Care Act (IRC §1411). It applies to the lesser of: (1) your net investment income (capital gains, dividends, interest, etc.), or (2) the amount by which your Modified Adjusted Gross Income (MAGI) exceeds the threshold — $200,000 for single filers, $250,000 for married filing jointly, $125,000 for married filing separately. It is not inflation-adjusted, so the same thresholds have applied since 2013. The NIIT is in addition to regular capital gains tax — a single filer with long-term gains at the top tier pays 20% + 3.8% = 23.8% on those gains.
Are there states that also tax capital gains?
Yes — most states with an income tax treat capital gains as ordinary income and tax them at the same rates as wages. A few states (like California) have no separate, lower rate for long-term gains. Some states (like Hawaii) have a preferential rate. A handful have no income tax at all (Florida, Texas, Nevada, Washington, Wyoming, South Dakota, Alaska) and therefore no capital gains tax. This calculator covers federal capital gains tax only; see CiteTax's state income tax calculators for state-level liability.
Related tools
Enter your income and filing status to see exactly how the 2025 U.S. tax brackets apply — marginal rate, effective rate, and every dollar of tax shown bracket by bracket.
Open tool →Marginal vs. Effective Tax Rate ExplainerMost people misunderstand how tax brackets work. This tool shows exactly how a raise, bonus, or extra income is taxed — and why your marginal rate isn't what you actually pay.
Open tool →State Income Tax CalculatorState income tax calculators for all 50 states and DC — select your state to see its bracket structure and compute your liability, with each rate cited to the state revenue department.
Open tool →