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US · 2025

Capital Gains Tax Calculator (US)

Calculate your US capital gains tax for 2024/2025. Covers short-term and long-term rates, NIIT, all filing statuses, and optional state tax. See your net proceeds after tax.

Last reviewed: 5 September 2025Source: HMRC — Tax ratesUpdated every: tax year
Capital Gains Tax Calculator (US) · USUS Tax

Rates & sources

UK tax rates and thresholds, as published by HMRC. Scotland and Wales have devolved rates for income tax and property transactions.

Source: HMRC — Tax rates — figures refreshed at the start of each tax year.

When to use this calculator

  • Before accepting a pay change, bonus, pension contribution, or salary-sacrifice option.
  • When you want to compare employed, self-employed, or dividend-based income scenarios.
  • When you need a simple take-home estimate before running payroll or filing returns.
  • When you are approaching the £100,000 income level and want to understand the personal allowance taper effect.
  • When you are planning a salary sacrifice arrangement and need to see the net pay impact before agreeing terms.

A realistic US planning example

Use these sample inputs as a quick scenario test, then change one variable at a time to compare outcomes.

Capital Gain ($)

50000

Holding Period

Short-term (held ≤ 1 year)

Filing Status

Single

Other Taxable Income ($)

$55,000

After entering these figures, review federal cgt, niit (3.8%) and state tax together rather than in isolation — each metric tells a different part of the story. Then rerun the tool with one input adjusted to see which variable has the biggest effect on all three outputs before you settle on a plan.

How to read your results

Federal CGT

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

NIIT (3.8%)

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

State Tax

Review this figure alongside your gross income so you can understand the true cost of deductions and plan around any thresholds before the tax year closes. If the figure looks higher than expected, check whether any pension or gift-aid contributions could reduce your taxable income.

Total Tax

Review this figure alongside your gross income so you can understand the true cost of deductions and plan around any thresholds before the tax year closes. If the figure looks higher than expected, check whether any pension or gift-aid contributions could reduce your taxable income.

Effective Rate

The effective rate lets you compare options on a true like-for-like basis rather than being misled by different compounding periods or fee structures. Use it to cut through headline marketing rates when shortlisting providers or products.

Net Proceeds

Use this metric to compare scenarios side by side and understand how changes in the key inputs drive the final outcome. If the figure surprises you, isolate one variable at a time and rerun the calculation to identify which assumption is responsible.

Method & assumptionsAuthoritative sources

This calculator applies the 2024 federal capital gains schedule. Short-term gains are taxed as ordinary income — federal tax is estimated by computing the marginal bracket difference between your other income alone and your other income plus the gain. Long-term gains use the preferential 0%, 15%, and 20% tiers based on taxable income and filing status. The 3.8% Net Investment Income Tax applies to long-term gains when modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly), per ACA rules.

State tax is applied as a flat rate on the full gain — enter your state’s effective rate for a blended estimate. The calculator does not model AMT, depreciation recapture on real property (25%), or collectibles (28%). The effective rate is total tax divided by the reported gain. Results are estimates only; consult a CPA or enrolled agent before filing.

Common mistakes

  • !Entering gross income when you really want take-home pay, or vice versa.
  • !Ignoring pension contributions, deductions, or local tax rules that change the result.
  • !Comparing monthly and annual figures without standardising them first.
  • !Overlooking the National Insurance threshold changes that apply mid-year when rates or bands are adjusted in a Budget.
  • !Assuming a salary sacrifice benefit reduces take-home pay by the full gross amount, rather than only the after-tax cost.

What to do next

  • Check the same scenario with related pay or deduction calculators to see the full picture.
  • Keep a copy of the assumptions you used so you can compare next tax year or pay period accurately.
  • Read the related guides below if you are choosing between multiple income or deduction options.
  • If you are self-employed, run the self-employment tax calculator alongside this result to compare the net position against employed income.
  • Check whether increasing your pension contribution by even one or two percent changes the take-home significantly — use the pension calculator next.

Frequently asked

Short-term capital gains apply to assets held one year or less and are taxed as ordinary income, using the same progressive brackets as your wages — up to 37% federally. Long-term gains on assets held more than one year qualify for preferential rates of 0%, 15%, or 20% depending on your taxable income and filing status. For 2024, the 0% rate applies up to $47,025 for single filers. Choosing when to sell an asset can significantly affect your tax bill, and holding past the one-year mark is one of the most straightforward ways to reduce it.

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