A swap is a disposition
The CRA treats crypto as property, not money. Trading one coin for another is legally a disposition of the coin you gave up — exactly as if you sold it for cash and immediately rebought a different asset. That disposition realizes a capital gain or loss, even though your account never touched fiat.
Valuing the trade in Canadian dollars
You measure the gain in Canadian dollars at the time of the swap. Take the fair market value in CAD of what you disposed of, subtract your pooled ACB for it, and that’s your gain or loss. Stablecoins are no exception — converting BTC to USDC is still a crypto-to-crypto disposition.
Why it spirals
Active traders and DeFi users can generate hundreds of swaps a year across exchanges and wallets. Each one is a taxable event needing a CAD price and a pooled-ACB lookup at that moment. Miss a batch and both your gains and your cost bases downstream are wrong — the errors compound through the chain.
What to keep
For every swap: date, coins in and out, quantities, and the CAD fair market value at the time. Exchange CSVs rarely give you CAD values or pooled cost base, so reconstructing them after the fact is the painful part of crypto filing.