What Is Capital Gains Tax?
A sale closes. The number on the wire looks like the whole story. Then the question arrives, usually later than it should: how much of that is actually yours to keep?
Capital gains tax sits between the sale price and the amount that stays. For most people it surfaces once or twice in a lifetime, which is precisely why it tends to be misunderstood in the moments when the stakes are highest. The mechanics are not complicated. The consequences of not understanding them before a sale can be considerable.
At Avion Wealth, this comes up most often not as a tax question but as a timing question, and it usually arrives attached to something larger: a business under letter of intent, an equity award approaching a vest, a property held for three decades.
How a Capital Gain Is Calculated
A capital gain is the difference between what an asset sold for and what it cost. The cost figure is the basis. The sale figure is the sale price. The gain is the spread between them.
This is the first point where assumptions go wrong. The tax normally applies to the gain, not to the full amount received at closing. A property that sold for a substantial sum may carry a modest gain if the basis is high. A stock position acquired decades ago at a low basis may carry a gain approaching the entire sale price.
Basis itself is not always the original purchase figure. It may be adjusted upward by capital improvements to a property, adjusted for reinvested distributions, or reset entirely at death through a step-up in basis for inherited assets. Basis records that are incomplete or unavailable are a common and expensive problem at sale, and in some cases they are reconstructable only with effort.
Realized and Unrealized Gains Are Not the Same Thing
An asset that has grown in value but has not been sold carries an unrealized gain. It exists on paper. In most cases it is not taxed until a sale occurs.
The logic holds up under examination. An unsold asset may rise and fall many times before it is ever disposed of, which makes any tax on a paper figure both difficult to measure and difficult to unwind if the value later falls.
The practical consequence is more useful than the theory. Because tax generally attaches at sale, the decision of when to sell is one of the few variables in this entire subject that a person may have meaningful say over. Most of the rest is fixed by statute.
The Holding Period Distinction
Once a gain is realized, one factor generally does more to shape the outcome than any other: how long the asset was held before it was sold.
An asset held for one year or less generally produces a short-term gain. An asset held for more than one year generally produces a long-term gain. Short-term gains are generally taxed as ordinary income, at the same kind of rates that apply to wages. Long-term gains are generally taxed at lower rates
| Short-Term Gain | Long-Term Gain | |
|---|---|---|
| Holding period | One year or less | More than one year |
| General tax treatment | Generally taxed as ordinary income | Generally taxed at lower rates |
| Rate reference point | The same kind of rates that apply to wages | A separate, lower set of rates tiered by taxable income |
| Where the clock starts | Varies by how the asset was acquired | Varies by how the asset was acquired |
The line is genuinely a line. A gain realized at eleven months is generally short-term. The same gain on the same asset realized at thirteen months generally receives long-term treatment. Two sellers with identical assets and identical gains may keep meaningfully different amounts, and the only difference between them may be a few weeks on a calendar.
Holding periods are not always intuitive to calculate. Assets acquired in tranches, shares received through equity compensation, and positions inherited or received as gifts each follow their own rules for when the clock starts. Where a holding period is close to the one-year mark, it may be worth confirming rather than assuming.
Four Factors That Interact With the Gain
The gain rarely stands alone on a tax return. Several other elements may affect the outcome and deserve review alongside it.
- Other income in the year of sale. Long-term capital gains rates are tiered by taxable income, so the rest of the year’s income may influence which rate applies to the gain. A sale that lands in a high-income year may produce a different result than the same sale in a lower-income year.
- Additional taxes that may apply. An additional net investment income tax may apply to investment income above certain income thresholds. Whether it applies depends on the situation.
- Capital losses and carryforwards. Realized losses may offset realized gains, and unused losses may generally be carried forward to future years. Losses already banked from prior years are frequently overlooked as an asset at sale.
- State tax treatment. State treatment of capital gains varies. For clients who have relocated, or who are considering relocation around a liquidity event, the question of which state has a claim on the gain is not always straightforward and may depend on residency, timing, and the nature of the asset.
Where Capital Gains Surface in Planning
For the clients we work with, capital gains rarely appear in isolation. They appear inside a transition.
A business owner sells the company. A senior executive exercises and sells equity compensation, where the holding period interacts with the type of award and with the timing of the exercise. A family sells property held across decades, with a low basis and possible improvements to substantiate. A concentrated stock position is finally diversified, which raises the question of whether the sale happens in one year or across several.
In each case the gain is large enough that the surrounding decisions carry weight. And in each case the useful window for those decisions is before the sale, not at filing.
Timing, Sequence, and Coordination
Capital gains tax is rarely just a tax question. It touches when a sale happens, how it is structured, what else is occurring in that year’s income, and how the proceeds fit the plan that follows.
Those elements interact, which means they are difficult to evaluate one at a time. Considered together, and coordinated alongside your existing legal and tax professionals, the outcome tends to reflect a decision rather than a surprise.
Coordination Before the Sale
For those approaching a business sale, planning around a concentrated stock position, navigating equity compensation, or preparing for the transition into retirement, Avion Wealth offers a complimentary Second Opinion Service, a review of how the tax picture fits within your broader wealth strategy and how the pieces of your plan work together. There is no obligation.
To your success,
The Avion Wealth Team
Frequently Asked Questions
Do I owe capital gains tax on an investment that has gone up if I have not sold it?
Generally no. An unrealized gain on an asset you still hold is not typically taxed until the asset is sold. Certain assets and account structures follow different rules, so specific holdings may be worth confirming.
How long do I need to hold an asset for long-term treatment?
More than one year. An asset held for one year or less generally produces a short-term gain, taxed as ordinary income. Assets acquired in multiple purchases, or received through equity compensation, gift, or inheritance, follow specific rules for when the holding period begins.
Is capital gains tax calculated on the sale price or the profit?
On the gain, which is the sale price less your basis. Basis is generally what you paid, subject to adjustments such as capital improvements or a step-up in basis at death. Incomplete basis records are a common complication at sale.
Can capital losses reduce capital gains?
Yes. Realized losses may generally offset realized gains, and unused losses may generally be carried forward to later years. How this applies depends on the character and amount of the gains and losses involved.
Does the state I live in affect what I owe on a sale?
It may. State treatment of capital gains varies, and residency, timing, and the type of asset can all affect which state has a claim. This deserves review well in advance where a relocation and a sale may occur near each other.