Enter your long-term capital gain, other taxable income, and MAGI to calculate your complete 2026 federal capital gains tax, including the 3.8% NIIT surtax where it applies.
Capital Gains Tax Calculator
Live| Taxed at 0% | $9,450.00 |
| Taxed at 15% | $10,550.00 |
| Taxed at 20% | $0.00 |
| Capital gains tax | $1,582.50 |
| NIIT (3.8% surtax) | $0.00 |
| Total tax on this gain | $1,582.50 |
The 2026 brackets used
Single filer with $40,000 other taxable income, a $20,000 long-term gain, and MAGI of $60,000: capital gains tax of $1,582.50 (spanning the 0% and 15% bands), plus $0 NIIT since MAGI is under the $200,000 threshold - $1,582.50 total.
Step-by-step guide
- Confirm your gain is long-term - the asset must have been held for more than one year (not exactly one year) to qualify for these preferential rates.
- Enter your other taxable income - your capital gains stack on top of this for bracket purposes, so this number determines where your gain "starts" on the ladder.
- Read your bracket breakdown - most people's gains span more than one rate, not just a single flat percentage.
Why your gain "stacks on top" of your other income
A common misconception is that a large enough capital gain gets taxed entirely at one rate based on your total income. In reality, your ordinary income (wages, interest, etc.) fills the lower brackets FIRST, and your capital gain is then evaluated against what's LEFT of each threshold. This is why a modest earner with a large one-time gain - like someone selling a long-held stock position or a business - can have PART of that gain taxed at 0%, part at 15%, and part at 20%, all within the same sale, depending on exactly where each dollar of the gain falls relative to the thresholds.
How NIIT stacks a third layer on top of high earners
For taxpayers above the NIIT threshold, capital gains face two separate federal charges, not one - the standard 0%/15%/20% capital gains rate, and then the 3.8% Net Investment Income Tax on top of that, calculated completely independently under its own rules. This means a gain that falls in the 15% capital gains bracket can effectively cost 18.8%, and a gain in the 20% bracket can effectively cost 23.8%, once NIIT applies. Unlike the capital gains brackets, which are indexed for inflation each year, the NIIT thresholds ($200,000 single/HoH, $250,000 MFJ) have been fixed since 2013 and never adjusted - meaning more taxpayers face this additional layer every year as incomes rise.
Common mistakes
Frequently asked questions
What exactly counts as "long-term" for capital gains purposes?
You must hold the asset for more than one year - at least one year and one day. Selling on the exact one-year anniversary still counts as short-term, not long-term.
Do qualified dividends get the same treatment as long-term gains?
Yes - qualified dividends (generally from stocks held more than 60 days around the dividend date) are taxed at the same preferential 0%/15%/20% rates as long-term capital gains, not as ordinary income.
Is unrealized appreciation in my portfolio taxed?
No - an investment that has risen in value but hasn't been sold creates only an unrealized gain, which isn't taxed. Capital gains tax applies only when you actually sell and lock in the profit.
Does NIIT replace the regular capital gains tax, or add to it?
It adds to it - NIIT is a separate 3.8% surtax calculated independently and stacked on top of your regular 0%/15%/20% capital gains tax, not an alternative to it.
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