Billionaires Bill Gates and Warren Buffett said limits on charitable deductions could hurt giving—but only among the lesser rich.
In a joint interview on CNBC, Gates and Buffett said proposals to possibly limit or cap charitable deductions would not have changed their own giving. The charitable deduction's impact has become a flashpoint in Washington as President Barack Obama and some Democrats have proposed limiting deductions for high earners.
Since both Gates and Buffett have given away tens of billions of dollars, they were only able to use a tiny sliver of the deduction.
"I got to use less than 1 percent of what I gave away," Buffett said.
Still, both said that for the lesser rich, deductions matter and could reduce giving.
"I think the charitable deduction is a good thing," Gates said. "If they limit it to 28 percent, I don't think it will have a dramatic impact, but maybe a slight negative impact, but not super dramatic."
He added that if they eliminated the charitable deduction altogether "that could change behavior and that would be unfortunate."
Buffett said that "for people at the high end, I don't think it will make a lot of difference, but in the intermediate level it could make a fair amount of difference."
—BY CNBC's Robert Frank. Follow him on Twitter: @robtfrank