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A stock option isn’t taxed when you get it. The tax bill arrives when you exercise, and for most employees that means the gap between the share’s market value and your exercise price counts as employment income. Sell the shares later and any further gain or loss is a capital gain or loss. That’s the stock option tax rule in one breath, and the details below decide how big the bill is.
When do you pay tax on a stock option?
Two moments matter. The first is exercise, when you buy the shares at your option price. The CRA works out a benefit: the fair market value of the shares, minus what you paid, minus anything you paid for the option itself. The second is the sale, when you compare the price you got with your cost for tax purposes, which is the value used at exercise plus the price you paid.
Which one triggers tax first depends on who your employer is. The CRA treats a Canadian-controlled private corporation (a CCPC, the typical startup) differently from everyone else.
| Public or other non-CCPC employer | CCPC employer | |
|---|---|---|
| Employment benefit taxed | In the year you acquire the shares | In the year you sell the shares |
| Half-benefit deduction | Yes, if the option price wasn’t below market value at grant and other tests are met | Yes, if you also held the shares at least two years |
| CPP withheld on the benefit | Yes | No |
| EI withheld on the benefit | No | No |
What does the 50% deduction do?
It’s the reason option income is taxed lightly. If you qualify, you deduct half of the benefit, so only half of it stays in your taxable income. The main test is that the option price was at least the share’s market value on the day the option was granted. For a large non-CCPC employer there’s a newer catch: options granted from July 2021 only get the deduction on shares that vest within a $200,000 yearly limit. Ask your employer’s plan administrator which side of that line your grant falls on, because the answer changes your tax by thousands.
What does it cost you in real dollars?
Take someone in Ontario earning $80,000. They exercise 1,000 options at $10 when the shares trade at $25. The benefit is $15,000.
We ran the numbers through the marginal tax rate calculator by adding the benefit as extra taxable income. With no deduction, income tax rises from $14,128 to $18,575, an extra $4,447. With the half deduction only $7,500 is added, and tax rises to $16,352, an extra $2,224. Same options, half the bill.
Later they sell at $30. Their cost is $25 a share, so the gain is $5,000. The capital gains tax calculator shows $741.25 of extra Ontario and federal tax on that, and they keep $4,258.75. A drop below $25 would be a capital loss instead, and you can’t use it against the employment benefit you already reported.
| Step | Amount | Extra tax |
|---|---|---|
| Benefit at exercise, no deduction | $15,000 | $4,447 |
| Benefit at exercise, with 50% deduction | $7,500 taxable | $2,224 |
| Gain on sale at $30 | $5,000 | $741.25 |
These figures assume an $80,000 salary, the 2026 Ontario and federal rates, and the half deduction already claimed when the sale is taxed. Our tools don’t model options directly, so treat them as a close estimate.
What if you can’t sell right away?
It happens all the time, especially at a public company with a trading blackout, or at a startup where shares can’t be sold at all. Under the non-CCPC rules above, the benefit is taxed in the year you acquire the shares whether or not you can sell. Think of Tomas in Mississauga, who exercises in December and holds the shares through a lockup. His $15,000 benefit lands on this year’s return, and his employer may have withheld only part of the tax. If his marginal rate is high, the bill at filing can be a nasty surprise. Ask payroll what will be withheld and set aside the rest.
With a CCPC employer, the timing is kinder: nothing is taxed on exercise, and the benefit comes into income in the year you sell.
Mistakes that cost people money
The big one is forgetting that the tax on exercise is due even if you haven’t sold a share. With a non-CCPC, you can owe tax on paper value while holding shares you can’t yet sell. Set cash aside before you exercise, and ask your payroll team what they’ll withhold on the benefit.
Another is reporting the sale with the wrong cost. Your cost isn’t the option price alone. It’s the value used at exercise, which is why brokers’ statements often need a fix. Keep the exercise notice and your T4 slip, because the T4 shows the benefit and whether the deduction was claimed.
And if the benefit lands in a year when your income spikes, a larger RRSP contribution can soften it. The RRSP calculator shows what a deduction would save. For a rough sense of how a lump of extra pay is taxed, the bonus tax calculator is a decent stand-in, though it adds CPP and EI that don’t apply to option benefits.
The sources behind this page
The rules above come from the Canada Revenue Agency‘s pages on employee security options and the security options deduction, checked in 2026. The tax figures come from the 2026 federal and Ontario rates used by our calculators. Half of a capital gain is taxable; the proposed increase to that share was cancelled in March 2025. How the rules apply to your particular plan isn’t covered here, so read your option agreement and your T4 before you file. This site is independent of the CRA and any government.
Frequently asked questions
When are stock options taxed in Canada?
For most employers you're taxed in the year you acquire the shares. If your employer is a CCPC, the benefit is deferred until you sell them.
What is the stock option deduction?
It lets you deduct half of the employment benefit, if the option price wasn't below market value at grant and other tests are met. CCPC shares also need a two-year hold.
Do you pay CPP on stock option income?
A non-CCPC employer must withhold CPP on the benefit but not EI. A CCPC withholds neither on a non-cash benefit.
How much tax on a $15,000 benefit in Ontario?
On an $80,000 salary, $4,447 more income tax with no deduction and $2,224 with the half deduction.
What happens when you sell the shares?
The difference between your sale price and your cost is a capital gain or loss. Half of a gain is taxable.
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