Definition
The superficial loss rule is a Canada Revenue Agency (CRA) anti-avoidance rule, sometimes called the "30-day rule," that prevents you from claiming a capital loss while effectively keeping your position. It matters to anyone tax-loss harvesting Bitcoin or other crypto near year-end. This is general information, not tax advice; consult a Canadian tax professional for your circumstances.
When the rule applies
Set out in section 54 of the Income Tax Act, the rule is triggered when you (or an affiliated person) acquire the same or identical property within 30 days before or 30 days after a disposition at a loss, and still hold it at the end of that window. "Affiliated persons" include your spouse or common-law partner, a corporation you control, and registered accounts such as your RRSP or TFSA — so selling Bitcoin at a loss and rebuying it inside your TFSA can also trip the wire.
What happens to the denied loss
The loss is not gone forever. The denied capital loss is added to the adjusted cost base of the repurchased property, so the benefit is deferred until you eventually dispose of that property in a way that does not re-trigger the rule. In practice, the simplest way to crystallize a genuine crypto loss is to avoid rebuying the identical coin (in any affiliated account) for at least 31 days.
Because identical-property rules and ACB pooling interact, the superficial loss rule is closely tied to how Canadian filers compute their capital gains and losses.
In Simple Terms
The superficial loss rule is a Canada Revenue Agency (CRA) anti-avoidance rule, sometimes called the “30-day rule,” that prevents you from claiming a capital loss…