Short-term vs long-term capital gains
An asset held for more than a year produces a long-term gain, taxed at 0%, 15% or 20%. Held a year or less, the gain is short-term and taxed as ordinary income. For a single filer with $80,000 of other income, a $100,000 gain costs $15,000 of federal tax if long-term and $23,164 if short-term.
Counting the holding period
The holding period starts the day after you buy and includes the day you sell. More than one year makes the gain long-term.
States
Most states tax both kinds of gain as ordinary income, so the difference is mostly federal. A few states treat long-term gains more lightly: see capital gains tax by state.
Try both with the calculator. Estimates, not tax advice.
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