US Capital Gains Tax Calculator

Estimate the additional US federal tax on a capital gain.

Tax year

Thresholds are loaded for the selected US tax year.

Other taxable income

USD

Taxable income before the capital gain, after deductions.

Taxable capital gain

USD

Positive net gain after cost basis, selling expenses and applied losses.

Holding period

Long-term means longer than one year in this simplified calculator.

Filing status

Prepare the inputs

Select the tax year first. Then enter other taxable income and the positive net capital gain. Choose the holding period and US filing status. The gain should already account for cost basis, direct selling expenses and capital losses that you apply.

Short-term and long-term treatment

A gain from an asset held for one year or less is treated as short-term and taxed like additional ordinary income. For a holding period longer than one year, the calculator uses the 0%, 15% and 20% federal long-term bands. Other income fills the lower ranges first.

Example result interpretation

With USD 80,000 of other taxable income and a USD 20,000 long-term net gain, the gain is allocated across the remaining long-term bands. The result shows additional federal tax, the rate allocation and possible NIIT. It is not the household’s total income-tax bill.

NIIT and state tax

The calculator estimates Net Investment Income Tax from the gain and the threshold stored for the filing status. Actual NIIT uses modified adjusted gross income and may differ. State income tax is not included.

Limits of the estimate

The primary-residence exclusion, collectibles, Section 1250 gain, Qualified Small Business Stock, wash sales, credits, special deductions and loss carryovers are not calculated. Verify the asset treatment and tax return separately from this planning estimate.

Data date and sources

Year-dependent thresholds come from the centrally maintained US tax rules. Technical references include the IRS Capital Gains and Losses topic and the IRS Net Investment Income Tax guidance.

Frequently Asked Questions

When is a capital gain long-term?

This calculator treats a gain as long-term when the asset was held for more than one year. A holding period of exactly one year or less is treated as short-term.

How do I determine cost basis?

Cost basis often starts with purchase price and may include acquisition fees and permitted adjustments. Selling expenses further reduce the gain. Enter the resulting net gain in the calculator.

How does my other income affect the rate?

Other taxable income fills lower brackets first. A long-term gain may therefore span the 0%, 15% and 20% bands, while a short-term gain moves through ordinary income-tax brackets.

How are capital losses handled?

Apply eligible capital losses against gains before entering the result. The calculator does not track loss categories, carryovers or annual limitations.

Are state tax and NIIT included?

The estimated Net Investment Income Tax is included. Any tax imposed by a state is not calculated.

Which tax year do the thresholds cover?

You can select 2017 through 2026. Long-term thresholds, ordinary income-tax brackets and NIIT thresholds are loaded for the selected year.