This is a simple-sounding question that can be, in the real world of tax planning, very hard to answer. The simplest calculation is that, in 2020, under the just-released tax tables, single taxpayers will pay 0% capital gains taxes if their adjusted gross income is $40,000 or below, while joint taxpayers will pay 0% below $80,000 of adjusted gross income. After that, the 15% rate ki