Superficial loss calculator (Canada): is your loss denied?
You sold at a loss, then bought back, or a put got assigned. Is the loss denied? Put in your dates and share counts to see how much you can claim now and where the rest goes.
How it works: a loss is superficial when you, or someone tied to you like your spouse, buy the same shares in the 30 days before or the 30 days after the sale, and still own some at the end of day 30 after it. An assigned put counts as a buy. If you bought back fewer shares than you sold, only part of the loss is denied: loss × the smallest of (shares sold, shares bought back, shares owned on day 30) ÷ shares sold. The denied part is added to the ACB of the shares you bought back, so you claim it when you sell them. If you bought them before the sale, they're already in your average cost, so it's added to all the shares you still own. In a TFSA or RRSP it can't be added to anything, so it's gone. Dates are trade dates. Rule as of October 2026 (CRA guide T4037).
The loss isn't gone, it moves
In a regular account, a superficial loss is only delayed. The cash you lost is the same either way. What changes is the year you can use it. Say you sold at a loss in November to cancel out a gain from earlier in the year. If a put you sold is assigned three weeks later, that loss slides into the new shares' ACB. Your gain this year is now taxed in full, and the loss waits until you sell the new shares. The full worked example, with a put, is in the superficial loss rule with options.
Where the wheel trips it
In the wheel strategy you sell puts on stocks you like. So after a loss sale, the next move is often a new put on the same stock. That's the trap. If it's assigned inside the 30 days, you bought the shares back. A call you buy is a right to buy them, so plan as if it counts too. The clean fix is to wait 31 days, or sell the put on a different company. Check every account, including your TFSA, RRSP and your spouse's. To track the ACB through a whole wheel cycle, use the ACB calculator for options.
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