My situation: I transferred stock out of Robinhood and into Webull due to a promotion they were doing. If i sell all my stocks on webull, does the IRS already know how much i originally paid for it and what my capital gain is? or will i get taxed on the whole amount? (For example, if i buy 1 apple for $80 on robinhood, transfer stock to different brokerage, webull. When I sell that stock for $100, will i get taxed for $20 or $100 profit. )
