He would have faced standard federal income tax on that gain plus another tax known as the net investment income tax, a Medicare tax substitute for rich investors. Let’s assume MacKenzie faced a mere 2.5 percent annual tax — more below on the rationale for that figure — on her gains. Our current federal tax system lets him wait until he sells his Amazon shares before he faces any legal obligation to pay tax. Which means that a big part of Bezos’ eventual $49.3 billion tax payment doesn’t really rate at all as a tax in a true economic sense. The 22.7 percent annual income tax rate that taxpayer faces runs over nine times the effective tax rate that an insanely wealthy character like Jeff Bezos faces.