What factors make CRA treat frequent trading inside a TFSA as carrying on a business?

CRA and the courts look at a cluster of factors similar to those used generally to tell investing apart from carrying on a trading business, rather than any single number or rule. These include the frequency and volume of trades, how short the typical holding periods are, the account holder's knowledge of or experience in the markets, how much time is devoted to the trading activity, and whether the overall pattern looks more like operating a business than passively holding investments for the long term.

None of these factors is decisive by itself, and there's no published bright-line threshold - no specific number of trades or dollar amount that automatically triggers a review or a reclassification. Instead, CRA looks at the whole picture: someone who trades occasionally and holds positions for months looks very different from someone making frequent, short-term trades with real market expertise and significant time invested in the activity, even if both are technically just trading in a TFSA. Because this is genuinely a fact-and-pattern-based assessment rather than a checklist with a fixed cutoff, anyone trading actively should think about how their overall pattern of activity would look under this kind of review, not just whether any single factor applies.