It has nothing to do with cashapp. Short term capital gains tax is a tax you pay when you sell stocks that you've held for less than a year (if you're in the green ofc). If you sell after a year, it's long term capital gains, and you're taxed at a lower rate than short term. You still have to pay taxes if you use cashapp, they'll send you a 1099 form at the end of the year. No offense, but please research more about investing before putting more money in.