How capital gains tax works in Canada
You're taxed only on the gain (proceeds minus what you paid), and only half of that gain is added to your income. That taxable half is then taxed at your marginal rate — so a capital gain is taxed more lightly than regular income.
Gains inside a TFSA, RRSP or FHSA aren't taxed at all, and the sale of your principal residence is generally exempt.