Capital Gains Tax Explained: What You Actually Owe When You Sell Stocks

You bought a stock, it went up, you sold it. Now the government wants a piece. How much? That's the capital gains tax question, and the answer depends on where you live, how long you held the stock, how much you earn, and what kind of account you held it in. This article walks through the full picture for both US and Canadian investors, with worked examples and the perfectly legal strategies to pay less.

The Basic Concept

A capital gain is the difference between what you paid for something and what you sold it for. If you bought Apple at $150 and sold at $200, your capital gain is $50 per share. Capital gains are taxed — but at different rates depending on how long you held the asset.

One important note that trips up beginners: you only owe tax when you sell. Holding a stock that's up 400% is not a taxable event. You can sit on unrealized gains indefinitely. The tax clock starts the moment you hit "sell."

US Rules: Short-Term vs Long-Term

The US tax code splits capital gains into two categories, and the difference matters a lot.

Short-term capital gains are profits on assets held for one year or less. These are taxed at your ordinary income tax rate — the same rate you pay on your salary. That can be as high as 37% at federal level, plus state tax.

Long-term capital gains are profits on assets held for more than one year. These get preferential rates: 0%, 15%, or 20%, depending on your income. Way lower than ordinary income for most people.

The difference is so large that the "held for more than one year" threshold should be written on the back of every investor's eyelids. Selling on day 364 can cost you thousands more than selling on day 366.

2026 US Long-Term Capital Gains Brackets

Rate

Single filers (taxable income)

Married filing jointly

0%

Up to $49,450

Up to $98,900

15%

$49,451 to $545,500

$98,901 to $613,700

20%

Over $545,500

Over $613,700

Notice the 0% bracket. This is a huge and underused opportunity. If your taxable income is under the threshold (~$49k single, ~$99k joint for 2026), you can realize long-term capital gains and pay literally zero federal tax on them. This is why "gain harvesting" in low-income years is a legitimate planning strategy.

Taxable income is calculated after deductions, so someone earning $65,000 who takes the standard deduction ($16,100 single for 2026) ends up with taxable income around $49,000 — which is right at the 0% long-term capital gains threshold.

Also watch out for the 3.8% Net Investment Income Tax (NIIT), which applies on top of the regular rates for higher earners (over $200k single, $250k joint). This is often forgotten in casual discussion and can add meaningful tax for high-income investors.

Worked US Example

You're single, earn $85,000 in salary, and sell stock for a $20,000 profit this year. You held the stock for 18 months (long-term).

Salary: $85,000

Standard deduction: $16,100

Taxable income (before the gain): $68,900

Add $20,000 capital gain → total taxable income: $88,900

Of your gain, $0 falls in the 0% bracket (you're over $49,450), the full $20,000 is in the 15% bracket → $3,000 federal tax on the gain.

Contrast: if the same gain had been short-term, it would be added to your salary and taxed at your marginal rate of 22% (on 2026 brackets), costing you $4,400 instead — an extra $1,400 just for selling too early.

Now imagine the same scenario but you earned only $30,000. Your taxable income with the gain would be about $34,000, well inside the 0% long-term capital gains bracket. You'd owe zero federal tax on the $20,000 gain. Same profit, completely different tax bill.

Canadian Rules: The 50% Inclusion Rate

Canada handles capital gains totally differently. Instead of giving you preferential rates, Canada says: only 50% of your capital gain is taxable, and that 50% is added to your ordinary income and taxed at whatever marginal rate applies to you.

This is called the "inclusion rate." At 50%, it means effective tax on capital gains is roughly half your marginal rate. For someone in the 30% marginal bracket, that's 15% effective tax on capital gains. For someone in the top bracket (53% in some provinces), it's about 26.5%.

The 2024 federal budget proposed increasing the inclusion rate to 66.67% on capital gains above $250,000 per year. That proposal was cancelled in March 2025 under PM Mark Carney's government. As of 2026, the inclusion rate remains at 50% across the board. If you've read older articles worrying about the 2/3 rate, it's not happening — at least for now.

Importantly, Canada does not distinguish between short-term and long-term gains. Whether you held the stock for 6 days or 6 years, it's the same 50% inclusion. There's no holding-period incentive the way there is in the US.

Worked Canadian Example

You live in Ontario, earn $75,000 in employment income, and sell stock for a $10,000 profit this year.

Capital gain: $10,000

Taxable portion (50%): $5,000

This $5,000 is added to your employment income → total taxable income: $80,000

At roughly a 31% combined federal + Ontario marginal rate, the tax on the $5,000 portion is about $1,550

Effective tax rate on your $10,000 gain: ~15.5%

Not bad. Compare that to paying ~31% on the full $10,000 if it had been, say, interest income. The 50% inclusion rate makes capital gains meaningfully tax-advantaged compared to most other types of investment income in Canada.

The Best Move: Don't Pay At All

Here's the biggest secret in capital gains tax planning: if your investments live inside the right account, you never pay capital gains tax at all.

US investors: Roth IRA and Roth 401(k). Every dollar of growth inside a Roth account is tax-free forever. You can trade within it as much as you want without triggering any capital gains. When you withdraw in retirement, you pay zero federal tax on the growth. Traditional IRAs and 401(k)s also avoid capital gains tax — gains get taxed as ordinary income on withdrawal, but not as you go.

Canadian investors: TFSA. Same idea. Every dollar of capital gain inside a TFSA is tax-free. You can day-trade in a TFSA (subject to some CRA scrutiny on extreme cases) and still pay zero capital gains tax. RRSPs defer the tax — you don't pay capital gains as you go, but the full withdrawal is taxed as ordinary income.

This is why the order of operations for most investors should be: fill up tax-advantaged accounts first, then worry about taxable accounts. Every dollar you put in a Roth or TFSA is a dollar you never owe capital gains tax on.

Tax-Loss Harvesting: The Legitimate Trick

If you do have investments in a taxable account and some of them are down, you can "harvest" those losses to offset your gains. It works like this:

Sell a losing position to realize the loss.

Use that loss to offset any realized gains from the same year, dollar for dollar.

If you have leftover losses, they can offset up to $3,000 of ordinary income in the US (or unlimited gains in Canada; excess losses carry forward).

Any remaining unused losses roll forward to future years indefinitely.

Buy a similar (but not identical) investment right away to stay in the market — just avoid the "wash sale" trap below.

Watch out for wash sale rules. In both the US and Canada, if you sell an investment at a loss and buy the same (or substantially identical) investment within 30 days before or after, the loss is disallowed. The workaround: sell VOO at a loss, buy IVV (a nearly identical S&P 500 ETF from a different issuer) instead. You stay in the market, keep the loss, comply with the rule. Many investors tax-loss harvest this way every December.

Common Mistakes

Selling just before the 1-year mark (US). If you're close to the long-term threshold, wait. The rate drop from 22–32% (ordinary) to 15% (long-term) can be massive.

Ignoring cost basis tracking. Your capital gain is (sale price − cost basis). Brokerages usually track this for you, but if you've transferred accounts, received stock as a gift, or done anything unusual, you may need to calculate it yourself. Missing cost basis records can cost you real money.

Trading in taxable accounts when you have unused tax-advantaged room. Every active trade in a taxable account is a taxable event. The same strategy inside a Roth or TFSA creates zero tax. If you have room and aren't using it, you're volunteering to pay more tax than you need to.

Forgetting provincial/state taxes. The federal rates above are just one layer. California adds 13% on top. Ontario, New Brunswick, and Quebec all have provincial taxes that stack on federal. Factor in your state or province.

The Bottom Line

Capital gains tax in three rules:

Hold stocks in tax-advantaged accounts (Roth IRA, TFSA, 401k, RRSP) whenever possible. You usually pay zero capital gains tax this way.

In taxable accounts, hold for more than one year (US) to get the preferential long-term rate. Canadians don't have a holding-period distinction but get a 50% inclusion rate regardless.

Use tax-loss harvesting to offset gains. It's free money if you're paying attention.

Most of the capital gains tax conversation is about optimizing within taxable accounts. But the single biggest win is avoiding the taxable account entirely by using your tax-advantaged room first. If you haven't maxed your Roth IRA or TFSA, that's the move before you worry about anything else here.