Capital gains tax calculator

You enter your filing status, other taxable income, the gain amount, the holding period (long or short), and your state. For long-term gains it locates your federal 0/15/20% bracket from your total taxable income, adds the 3.8% NIIT if your modified AGI is over the statutory threshold, and adds your state's effective top long-term capital-gains rate. For short-term gains it uses your ordinary federal bracket plus the state's ordinary rate. The result is the estimated total tax on the gain.

No. It is a labelled estimate. It simplifies in several ways: it uses your total taxable income to find the federal bracket (in reality the gain stacks on top of ordinary income), it applies a single state rate rather than each state's full brackets, and it ignores deductions, AMT, the additional Medicare tax and carry-forward losses. Use it for a quick directional figure, then confirm with the IRS, your state tax authority, or a tax professional.

Yes. When your modified AGI exceeds the statutory threshold ($200,000 single / $250,000 married filing jointly / $125,000 married filing separately - these are not inflation-indexed), the tool applies the 3.8% NIIT to the portion of the gain above the threshold. See the dedicated NIIT page for the details.

Several states give long-term capital gains a special rate or a partial exclusion (for example South Carolina excludes 44% of long-term gains, Arizona subtracts 25%). For those states the tool uses the resulting effective top long-term rate, not the headline ordinary rate, so the estimate is closer to reality. The exact treatment is shown on each state page.