taxable income is your adjusted gross income less either your itemized or standard deduction. in addition it can be further reduced by any QBI deduction
basically your non LTCG and qualified dividend income less your standard or itemized deductions get taxes as if that was your only income. however, the ordinary income pushes the LTCG and Qualified dividends into the 20% bracket. you have significant investment income in excess of $200,000 (varies based on marital filing status) so that excess gets hit with an additional 3.8% tax
