As Capital Gains (The "Investor" Route): Navigate to Income > Investment Income > Stocks, Mutual Funds, etc. (Schedule 3). If you trade as a hobby, this is where you report your totals.
As Business Income (The "Day Trader" Route): Select Self-Employment > Business Income (Form T2125). Because 0DTEs are high-frequency and held for less than a day, the CRA frequently regards them as a professional business operation rather than casual investing.
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