Despite being pegged to another asset - stablecoins are treated exactly the same way as other cryptocurrencies or NFTs from a tax perspective - so the taxation (or lack thereof!) all comes down to how long you've held the asset and the specific transaction, as well as how much you've earned in a year. You'll pay Income Tax on profits when you sell, swap or spend stablecoins you've owned less than a year, as well as earn an income in stablecoins. Meanwhile, you'll pay no tax at all when you sell, swap, or spend stablecoins you've owned more than a year, or if you earn less than €600 in a year in capital gains (or €256 a year for additional income through staking, etc.).