What are Stablecoins?
Stablecoins were developed as a way to tether the price of certain cryptocurrencies to the value of a fiat currency, such as the dollar. Some traders have used a strategy of purchasing stablecoins and then using them to "purchase", or trade for, other cryptocurrency. They are often surprised when they see a capital gain or loss incurred when these coins are traded for other coins or sold based on their price when purchased/sold.
Stablecoins such as TUSD, USDC, and USDT are still considered to be cryptocurrency, and as such, any coin-to-coin trade or sale of these coins would be considered a capital gain/loss.
When you import all of your exchanges and wallets, these will automatically populate for you and calculate with the rest of your cryptocurrency transactions for your reports.
A handy guide for stablecoins and fiat, for tax purposes
Buying stablecoins with fiat is NOT TAXABLE. EX: USD to TUSD is NOT TAXABLE.
Selling stablecoins into fiat is a TAXABLE transaction (capital loss or gain) and would appear on the 8949. EX: USDC to USD is a taxable transaction based on the difference between the value of the USDC when purchased and the value when it was sold.
Trading a stablecoin for a cryptocurrency is a TAXABLE transaction (capital loss or gain) and would appear on the 8949. EX: USDT to BTC is a taxable transaction based on the difference between the USDT value when purchased and the value when traded.
Trading another cryptocurrency for a stablecoin is also a TAXABLE transaction, with capital gains realized on the incoming coin. EX: BTC to USDT would have a taxable event on the value of the BTC when acquired and the value when sold.