Methodology & data sources

Transparency is the core of our E-E-A-T: this page documents where our capital-gains data comes from, how often it is refreshed, and the formulas behind every figure.

What this site covers

GainsCalc reports US capital gains tax for the 2026 tax year: the federal long-term brackets, the 3.8% Net Investment Income Tax (NIIT), the special collectibles (28%) and unrecaptured Section 1250 (25%) rates, and how all 50 states plus DC tax capital gains.

Federal figures

The 0%, 15% and 20% long-term capital gains breakpoints are the IRS 2026 inflation-adjusted amounts from Revenue Procedure 2025-32, cross-checked against the Tax Foundation's 2026 federal bracket summary and IRS Topic 409. The NIIT thresholds ($200,000 single / $250,000 joint / $125,000 married filing separately) are fixed in statute and not inflation-indexed.

State figures

State top individual income tax rates are from the Tax Foundation's 2026 state income tax data, with each state's capital-gains treatment (ordinary income, special rate, exclusion, or none) verified against state revenue-department guidance. Where a state gives a long-term exclusion (for example South Carolina 44%, Wisconsin 30%, Arizona's 25% subtraction), we show the resulting effective top long-term rate.

The "combined top rate"

For each state we derive an illustrative combined top long-term rate = federal 20% + 3.8% NIIT + the state's effective top long-term rate. This is the worst-case, top-bracket figure - it is not the effective rate a typical investor pays, since most fall in the 0% or 15% federal band and below the state's top bracket.

The calculator

The calculator locates your federal long-term band from your total taxable income, applies the 3.8% NIIT to income above the threshold, and adds your state's rate. It is a documented estimate: it uses total taxable income to find the bracket (rather than precisely stacking the gain on ordinary income), applies a single state rate rather than each state's full brackets, and ignores deductions, AMT and loss carryforwards.

Data sources

How calculations work

Calculators run entirely in your browser using standard, published formulas (shown on each tool page). We do not store your inputs.

Limitations

Figures are estimates for general information and may lag the underlying source or contain errors. Always verify against the primary source before relying on them. See our disclaimer.