This may be surprising, because the income tax purports to be imposed on “all income from whatever source derived” — and the I.R.S. is clear that this should be interpreted broadly to include not just a person’s salary, but also unemployment benefits, lottery winnings and even the cash value of bartered items.

Nonetheless, the income tax code has an explicit exclusion for funds received by gift and inheritance. The reason for this exclusion is not clear. Gifts and inheritances were originally subject to tax in the first income tax code and were removed in 1913. One tax scholar suggests “ the tale is simply one of the triumph of lobbyists .” As a result, a person can inherit $ 100 million, or even $100 billion, and owe no income taxes .

There is not even a requirement to report that money on a tax return. This allows the wealthy to believe that their tax liability is more burdensome than it actually is. Imagine a person with a $1 million salary (subject to $350,000 in income taxes) and a $100 million inheritance. Since he has to report only that $1 million, he might think he is paying taxes at a rate of 35 percent, when his actual tax burden is less than 1 percent of the wealth he acquired that year.

The second way that the ultrarich make their wealth is through building or investing in businesses. Jeff Bezos, the founder of Amazon, is the ultimate example of the successful entrepreneur. With wealth topping $160 billion, Mr. Bezos is not only the wealthiest American, but is also estimated to be the richest person in the world.

This enormous wealth has not resulted in much in the form of income taxes . Unlike many European countries, the United States does not tax the value of a person’s property; income taxes are due only if Mr. Bezos sells his stock. Mr. Bezos need not sell his stock in order to enjoy its value, because the tax rules allow him to borrow against the stock tax-free. Most troubling, Mr. Bezos and his family can avoid all income taxes on the growth in the value of his stock by holding it until his death. His heirs will then be treated as if they had purchased the stock at its market price, allowing them to sell it without owing any income tax.