When you sell an investment for more than you paid, the profit is a capital gain — and the tax on it depends less on how big the gain is than on how long you held the asset. Cross the one-year mark and the gain is long-term, taxed at preferential rates that are meaningfully lower than ordinary income tax. Sell at a year or less and it's short-term, taxed exactly like salary. Same asset, same profit, very different bill. This guide explains how the line is drawn, why it exists, and where investors accidentally end up on the wrong side of it.
The two regimes in plain terms
Short-term gains — assets held one year or less — are stacked on top of your other income and taxed at your ordinary marginal rate, the same brackets your paycheck flows through (see our tax brackets guide for how marginal rates work). If you're a high earner, that can mean a third or more of the gain, before state tax.
Long-term gains — assets held more than one year — get their own, lower rate schedule. Depending on your total income, a long-term gain is taxed at 0%, 15%, or 20% federally. For many middle-income investors the rate is 15%; at lower incomes a portion can genuinely be taxed at zero; at high incomes the top rate applies, plus (above certain thresholds) the 3.8% net investment income tax. The thresholds shift with inflation each year — our capital gains calculator applies the current-year figures to your numbers.
Why does the discount exist? Policy reasons: encouraging patient capital over rapid trading, and acknowledging that part of a multi-year gain is just inflation. You don't have to agree with the rationale to use it — the discount is one of the few tax breaks that requires nothing but waiting.
How the clock actually runs
The holding period starts the day after you acquire the asset and includes the day you sell. "More than one year" means exactly that — a sale on the one-year anniversary itself is still short-term; you need at least a year and a day. Investors who sell "right around a year" without checking the precise dates occasionally convert a would-be long-term gain into a short-term one by a single day.
A few clock rules that surprise people:
- Each purchase lot has its own clock. If you bought shares of the same fund in several batches, each batch has its own acquisition date. Selling "some shares" means your broker applies a lot-selection method — and choosing which lots to sell (specific identification) is often the difference between a long-term and short-term gain on the same sale.
- Reinvested dividends start new clocks. Every automatic reinvestment is a tiny new purchase with its own date. Selling an entire position you've held "for years" can still produce some short-term gain from recent reinvestments.
- RSUs start at vest, not at grant. For equity compensation, the holding period begins when shares vest and are delivered — the grant date is irrelevant. The vest-date value was already taxed as ordinary income (see RSU taxes explained); the capital-gain clock covers only movement after vest.
- Inherited assets are automatically long-term. Assets received by inheritance get long-term treatment regardless of how long anyone held them, alongside a stepped-up cost basis. Gifts, by contrast, generally carry over the giver's holding period and basis.
Why the difference is bigger than it looks
Suppose an investor with a healthy income realizes a $20,000 gain. As a short-term gain taxed at, say, an illustrative 32% marginal rate, the federal bill is $6,400. The same gain held past a year and taxed at 15% costs $3,000 — less than half. The waiting didn't change the investment at all; it changed which schedule the profit lands on.
Now layer on the stacking effect: short-term gains are ordinary income, so a large one can push your other income's top slice into a higher bracket, trigger income-based phase-outs, and raise the odds you cross the net investment income tax threshold. Long-term gains sit in their own schedule and interact more gently. The headline rate gap understates the full difference for high-income years.
Losses, netting, and the wash-sale trap
Gains and losses net against each other in a specific order: short-term losses first offset short-term gains, long-term losses offset long-term gains, and then the two nets offset each other. If losses win overall, a limited amount can offset ordinary income each year and the rest carries forward indefinitely. This ordering is what makes tax-loss harvesting work — realized losses are most valuable when they soak up short-term gains that would otherwise be taxed at ordinary rates.
The catch is the wash-sale rule: sell at a loss and buy the same (or a substantially identical) security within 30 days before or after, and the loss is disallowed for now — it gets added to the basis of the replacement shares instead. Automatic dividend reinvestment inside the window is a classic accidental trigger.
When waiting is the wrong move
The holding-period discount is valuable, but it's not a command. Holding a concentrated, volatile position for months purely to reach the one-year mark is taking real market risk to save a known tax amount — the stock can fall by more than the tax difference while you wait. This tension shows up constantly with vested RSUs, where the diversification argument often outweighs the tax argument. The rational way to decide is to put numbers on both sides: our capital gains calculator shows the exact dollar difference between selling now (short-term) and selling after the anniversary (long-term) for your income, which turns "should I wait?" from a feeling into an arithmetic problem.
The bottom line
Know each lot's anniversary date before you sell; prefer specific-lot identification over the default when it helps; remember that the vest date, not the grant date, starts the clock on equity compensation; and treat the one-year discount as one input in the decision, not the decision itself. The tax code rewards patience — but only when patience was the right call anyway.
Educational information, not tax advice. Capital-gains thresholds change annually and state treatment varies — verify current figures with IRS.gov and consult a licensed tax professional for your situation.