Capital Gains & Qualified Dividends Tax Calculator (2025)

What this calculator does (and why it’s useful)

Capital gains and qualified dividends have their own tax system in the U.S. In 2025, short-term gains (assets held one year or less) are taxed like wages at your ordinary rates, while long-term gains and qualified dividends may benefit from preferential brackets at 0%, 15%, and 20%. The catch is the IRS “stacking” rule: your ordinary income fills the lower layers of your taxable income first, and only then do your long-term gains/dividends spill into the remaining 0%/15%/20% space. This tool models that stack precisely. It also lets you toggle the Net Investment Income Tax (NIIT), a 3.8% surtax that can apply above fixed thresholds based on your Modified AGI.

Everything runs locally in your browser—no sign-in, no data stored. Use it to plan around year-end sales, harvest losses, or preview how a large distribution might land. When you’re done, export a tidy CSV to save your scenario.

How to use it

• Enter ordinary income: Wages, interest, business income, and short-term gains all count as ordinary. Keep long-term gains and qualified dividends out of this box.
• Add your capital items: Split gains into short-term (ordinary) and long-term (preferential). Add qualified dividends if you have them.
• Adjustments & deduction: Include above-the-line adjustments if relevant. Choose standard or itemized deduction. If you or your spouse are 65+ or blind, select the add-on(s); we’ll bump the standard deduction accordingly.
• NIIT toggle: Turn it on if you want to see the potential 3.8% surtax; thresholds are $250k (MFJ/QSS), $125k (MFS), and $200k (Single/HOH).
• Calculate & export: Click Calculate for instant results. Use Download CSV for a record of your inputs and outputs.

Interpreting your results

• AGI (approx.): Ordinary income + capital income − adjustments. (We treat AGI ≈ MAGI for most cases; specific add-backs for MAGI vary.)
• Taxable income: AGI minus the deduction you selected.
• Ordinary vs. preferential buckets: Your ordinary slice (including short-term gains) is taxed using the standard 2025 brackets. Whatever is left of your taxable income is where LTCG/QD are stacked into 0%/15%/20% layers.
• NIIT: If on, we compute 3.8% of the lesser of (i) your net investment income or (ii) MAGI above the filing-status threshold.
• Planning idea: If your ordinary income already fills the 0%/15% lanes, additional long-term gains may fall into the 20% band. Conversely, keeping ordinary income low can open up 0% or 15% space for LTCG/QD.

FAQ

Are all dividends “qualified”? No. They must meet holding-period and issuer rules. If not qualified, they’re taxed at ordinary rates.

Does this handle the 25% unrecaptured §1250 or 28% collectibles rates? Not in this version. Those special categories need additional inputs; consider running them separately or conservatively treating them as ordinary to avoid under-estimation.

Why doesn’t my tax equal a single percentage times my gains? Because LTCG/QD float on top of your taxable income. The portion that lands in each bracket gets that bracket’s rate—no single flat percentage applies.

Is NIIT optional? No, not on a real return. The toggle here is for planning; if your MAGI exceeds the threshold and you have net investment income, NIIT applies.

Next steps: check our 2025 Federal Income Tax Calculator for your full ordinary-income picture, and use the Sales Tax Calculator or Self-Employment Tax Calculator if those apply.