Capital Gains Tax on Stocks (Short-Term vs Long-Term)
Selling a winner feels great until tax season. Capital gains tax is why “I’m up 40%” isn’t the same as “I keep 40%.” Here’s the beginner framework for US stock sales — then run numbers in a calculator before you click sell.
Learn short-term vs long-term capital gains, why holding period matters, and how to sketch tax drag before exiting a winner. Pair with our free capital gains calculator.
What counts as a capital gain
Generally: sale proceeds minus cost basis on a capital asset (like shares). Positive difference = gain; negative = loss.
Cost basis usually starts as what you paid (plus commissions) and can adjust for corporate actions and certain account types.
The one-year line
Hold more than one year and you typically qualify for long-term rates (often 0/15/20% federally depending on income).
Hold one year or less and gains are usually taxed as ordinary income — which can be much higher.
Estimate before you sell
Know approximate tax drag so you’re not surprised. A capital gains tax calculator turns basis + proceeds + holding period into a planning sketch.
Remember state tax, NIIT, and your full return can change the bill — estimates aren’t filings.
Practical habits
Track purchase dates so you know when long-term kicks in.
Don’t hold a broken thesis only to save a few tax points — opportunity cost and further losses can dwarf the rate difference.
For multi-lot positions, understand average cost vs specific lot ID before year-end planning.
Next steps
Concepts stick when you apply them. Open a related calculator, run your own numbers, and — if you’re still learning execution — practice with paper trades before increasing real size. Browse more guides or the full set of free trading tools.
Free tool
Capital Gains Tax Calculator
Estimate short-term vs long-term capital gains tax on a stock sale using purchase price, sale price, holding period, and your tax bracket. Plan exits with tax drag in mind — not after the fact.
Other free tools
- Stock Market Simulator — Practice trading with fake money.
- Position Size Calculator — Risk the right amount on every trade.
- Compound Growth Projector — See how your portfolio grows over time.
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This is educational content, not financial advice. Investing carries risk — you can lose money. Do your own research and consider a qualified advisor for personal decisions.