Capital Gains Tax Calculator
Estimate federal, NIIT, and state tax on a short-term or long-term capital gain using 2026 brackets.
Other Annual Income (before this gain)
$
Capital Gain Amount
$
Holding Period
Filing Status
State (optional)
Total Tax on This Gain
$3,000
Federal Tax
$3,000
NIIT (3.8%)
$0
Effective Rate
15.0%
Net proceeds after tax
$17,000
How this calculator works
Capital gains are taxed very differently depending on how long you held the asset. Short-term gains (held one year or less) are taxed as ordinary income, stacked on top of your other income at your marginal rate. Long-term gains (held over a year) get preferential 0%, 15%, or 20% federal rates — also stacked on top of your other income, so where your ordinary income lands determines which LTCG bracket your gain falls into. High earners may also owe the 3.8% Net Investment Income Tax (NIIT) on top.
2026 long-term capital gains brackets
Single: 0% up to $49,450 taxable income, 15% up to $545,500, 20% above.
Married Filing Jointly: 0% up to $98,900, 15% up to $613,700, 20% above.
Head of Household: 0% up to $66,200, 15% up to $579,600, 20% above.
NIIT (3.8%) applies to investment income once MAGI exceeds $200,000 (single/HoH) or $250,000 (married filing jointly).
Example
A single filer with $90,000 of other income and a $20,000 long-term gain has $73,900 of ordinary taxable income after the standard deduction — comfortably inside the 15% LTCG bracket, so the entire gain is taxed at 15% federally ($3,000), with no NIIT since total income is well under $200,000.
Common Use Cases
- Deciding whether to hold an investment a few more weeks to cross into long-term treatment.
- Estimating the tax hit before selling stock, crypto, or a rental property.
- Checking whether a large gain will push you into NIIT territory.
- Comparing after-tax proceeds across different states before relocating.
FAQs
Why does holding period matter so much?
Selling one day before the one-year mark can mean paying your full ordinary income rate (up to 37%) instead of the long-term rate (at most 20% federally) on the same dollar of gain — one of the largest single tax-timing decisions most investors make.
Does this model my state's special capital gains treatment?
Most states tax capital gains as ordinary income using their regular brackets, which is what this calculator models by reusing each state's income tax rules. A few states have unique rules not modeled here — Washington, for example, levies a separate 7% excise tax only on gains above roughly $270,000, not its regular income tax (Washington has none). Verify your specific state's rules before relying on this for a real transaction.
Is the NIIT calculation exact?
It's an approximation using your entered income + gain as a stand-in for MAGI. Real MAGI calculations can differ (certain deductions and foreign income adjustments apply) — this is a planning estimate, not a substitute for a tax professional.