Capital Gains Tax Calculator

Short-term versus long-term

The federal code treats a gain as long-term if the asset was held more than one year before the sale. A long-term gain sits in a preferential rate schedule: 0 percent, 15 percent, or 20 percent depending on where the gain lands relative to the ordinary brackets. Short-term gains are taxed at ordinary income rates, which for most upper-middle-income households sit meaningfully higher than the long-term equivalents.

How the 0/15/20 stacking works

The preferential brackets stack on top of your ordinary taxable income. Ordinary income fills the ordinary brackets first. The long-term gain then stacks above it, and each dollar of gain is taxed at whichever long-term bracket that dollar lands in. It is possible for one sale to sit partly in the 0 percent zone, partly in 15, and partly in 20 depending on total income.

The 3.8 percent Net Investment Income Tax

High earners face an additional 3.8 percent surtax on net investment income above the modified AGI thresholds of $200,000 single or $250,000 married filing jointly. The surtax applies to the smaller of the investment income or the amount over the threshold, so on a large sale it typically applies to most or all of the gain.

Step-up in basis, the quiet estate planning tool

At death, most appreciated assets receive a new cost basis equal to their fair market value on the date of death. Heirs who sell shortly after inheriting typically owe little or no capital gains tax on prior appreciation. That is why the estate planning conversation for concentrated positions often centers on whether to sell now, gift during life, or hold until death and let the step-up wipe out embedded gain.

Deferral tools worth knowing about

Installment sales spread the gain across the years payments are received. A 1031 like-kind exchange defers gain on real property when the proceeds roll into replacement real estate on a strict timeline. A Deferred Sales Trust or Qualified Opportunity Zone investment can defer or partially eliminate gain when structured correctly. Each has meaningful rules and a CPA should be part of the transaction before it closes, not after.

The number this calculator produces is a good sanity check for the after-tax proceeds of a straightforward sale. Any real transaction with meaningful gain deserves a coordinated review with a tax professional before signing.