Profit on a sold asset is not taxed uniformly. The tax treatment depends on how long the asset was held, and the boundary between the two categories is a fixed holding period.
The holding period sets the classification
A gain on an asset sold within a defined period after acquisition is short-term. A gain on an asset held beyond that period is long-term.
The clock runs from the day after acquisition to the day of disposal, so a sale a single day early can move the entire gain into the other category.
The classification applies to the gain, not the taxpayer, so one investor can realise both kinds in the same year on different positions.
Short-term gains follow ordinary income rates
A short-term gain is added to ordinary income and taxed under the same schedule as wages, meaning it is layered on top of everything else earned.
Because the rate depends on total income, the cost of a short-term gain varies by household rather than being a fixed charge on the profit.
This is why frequent trading carries a tax drag that a buy-and-hold position does not, independently of transaction costs.
Long-term gains use a separate preferential schedule
Long-term gains are taxed under their own rate schedule, which is set below ordinary income rates at equivalent income levels.
The stated policy rationale is to encourage longer holding periods and to partially offset the effect of inflation on nominal gains.
The applicable rate still depends on total taxable income, so the preference narrows for higher earners rather than being uniform.
Losses offset gains before anything is taxed
Realised losses are netted against realised gains within each category first, and any remaining net loss can offset gains in the other category.
A net loss beyond that may be deductible against ordinary income up to an annual limit, with the excess carried forward to future years.
Rules restricting the repurchase of a substantially identical asset within a set window exist to prevent losses being harvested without any real change in position.
Nothing is taxed until the gain is realised
An unrealised gain on a held asset creates no liability, which gives the holder control over the timing of the tax event.
That timing flexibility is why gains are sometimes deferred into a year with lower expected income, and why tax-advantaged accounts change the calculus entirely.
Holding periods, rate schedules and offset limits are set by legislation and revised periodically, so current figures and a professional view matter for any actual decision.