61 percent of them work but don’t earn enough to owe income tax.
17 percent are students (who will pay plenty of taxes once they’re out of school), military families, people with disabilities and people who have lost their jobs—including victims of outsourcers like, well, Willard Mittford Romney.
22 percent are elderly.
The fact that they're not paid enough or are active duty military or are too old or disabled—maybe suffering from black lung or other diseases acquired on the job—does not mean they don’t contribute to America’s tax revenues. In fact, the poorest one-fifth of U.S. households pay a grinding 17.4 percent of their income in various federal, state and local taxes.
By the way, Willard Mittford, it's actually 46 percent, and people in southern red states—you know, where those "right to work" for less laws you like keep wages low—are disproportionately likely to pay no income taxes.
Also, many major corporations that are sitting on trillions of dollars in cash are paying little to no federal taxes. Many millionaires and billionaires pay no taxes.