Donald Trump has admitted he has taken advantage of tax loopholes to avoid paying federal income tax.
The Republican did not specify at the second presidential debate for how may years he had used the loophole.
“I absolutely used it, and so did Warren Buffett, and so did George Soros and so did many people who Hillary is getting money from,” he said.
He added that he understood the US tax system better than anyone else.
Mr Trump was recently exposed in the New York Times for making a loss of almost $1 billion in 1995 and using that loss to avoid paying income tax for almost two decades.
He was called a "genius" and "brilliant" for his tax management by former mayor of New York City, Rudy Giuliani, and his running mate, Mike Pence.
Hillary Clinton questioned why he has not released his tax returns yet - unlike every other presidential candidate, including Mike Pence - and he replied he will release them once they are no longer under audit.
When asked how he would make everybody pay their fair share of tax, Mr Trump said he would get rid of carried interest, and Ms Clinton said she was also not in favour of that tax.
Mr Trump kept demanding: “Why didn't you do it?”
“Because I was a Democratic senator with a Republican president,” Ms Clinton said.
“If you were an effective senator you would have done it,” insisted Mr Trump.
The Republican nominee promised voters he would cut taxes, but his opponent said the cut would only benefit people like him.
