If you're talking about Romney's "47%" comment, he didn't say that 47% didn't pay income tax. He said the "47%" got back more from the goverment than they paid. Significant difference.
An excerpt from an actual transcript (emphasis mine):
Romney: There are 47 percent of the people who will vote for the president no matter what. All right, there are 47 percent who are with him, who are dependent upon government, who believe that they are victims, who believe that government has a responsibility to care for them, who believe that they are entitled to health care, to food, to housing, to you name it. That that's an entitlement. And the government should give it to them. And they will vote for this president no matter what. And I mean, the president starts off with 48, 49, 48—he starts off with a huge number. These are people who pay no income tax. Forty-seven percent of Americans pay no income tax. So our message of low taxes doesn't connect. And he'll be out there talking about tax cuts for the rich. I mean that's what they sell every four years. And so my job is not to worry about those people—I'll never convince them that they should take personal responsibility and care for their lives. What I have to do is convince the 5 to 10 percent in the center that are independents that are thoughtful, that look at voting one way or the other depending upon in some cases emotion, whether they like the guy or not, what it looks like.
We can leave it as an exercise for readers to determine how "significant" the difference is. Actual video clip can be seen here in case someone doesn't believe the transcript.