I have a USDC question (and this just may be a misunderstanding of how the system works on my part), but I did several USD - USDC transfers within CoinbasePro last year in order to quickly lend out USDC on compound.
In several of my transactions the cost basis for the USDC, once I converted it back to USD, is not a 1 to 1 ratio. In fact, most of the time it records the trade as a loss (which, if we’re being honest, is great for taxes! But also, if we’re being honorable, is probably not the right way to handle it). See a screenshot below for an example of what I am talking about. This one is not very much, but since I have a lot of these trades it does add up over time and I believe it is making my tax burden a negative number (which again, is awesome if true, but I really don’t think it is).
To summarize: USDC is showing a cost basis which is causing a “loss” on the trade. My understanding is that all USD - USDC exchanges on CBP are 1 to 1 and would not incur any fees or cost basis differentials.