Found this:

http://madanca.com/blog/taxation-of-stock-options-for-employees-in-canada/

Public Companies – Employee Stock Options

Now, let’s move on to the taxation of stock options for public companies.

On the date that you are granted or receive stock options in an employer that is a publicly listed company, you do not have a personal tax consequence. However, on the date that you purchase the shares, you will get a taxable benefit equal to the difference between the exercise price of the shares and the market value of the shares on that date. You cannot postpone the timing of this taxable benefit.

Let’s assume you work for Coca-Cola Canada and the fair market value of the shares today is $30 / share. According to the option agreement, you can exercise or buy the shares for $10 / share. Therefore, the taxable benefit that will be included in your income at the time of exercise is $20 / share.

After buying the shares, you have two choices: (A) You can immediately sell the shares or (B) You can hold onto them if you believe they will increase in value in the future. If you choose to hold onto the shares and sell them in the future for a profit, the profit made from the sale will be classified as a capital gain and subject to tax. Whether you sell the shares or hold onto them, taxes will be deducted from your paycheck to account for the taxable benefit you realized on the purchase of the shares.