The differences come from what Saez and Zucman count as income. They count only earned income. They completely ignore transfer payments that make up more than 90 percent of the income of the bottom quintile and 50 percent of the income of the second quintile. By not counting transfer payments as income to the recipient households, they grossly understate income in the bottom two-fifths of the population. So, when they then divide the actual taxes paid by an income amount that is between two and nine times smaller than the real amount, the resulting tax rates are unbelievably too high.
