First of all, it really does look like you might be misinterpreting it. Getting a portion of your income taxes back would not put you into "zero or negative income tax" range, because there are still income taxes you paid that you did not get back, above and beyond the income taxes you paid and did get back.

My question is about payroll tax. Is that not a form of federal tax that comes essentially out of a person's income as well? Because the chart says that only 18.1 percent of people have both zero income tax and zero payroll tax (and 27.6 percent that have a zero sum of those two, which I assume means that their negative income tax balances out their payroll taxes). What is the distinction there? Is there a reason why payroll tax is ignored in the 47 percent number? I honestly do not know how payroll taxes work.