The New York Times reported Saturday that Trump reported a loss of $916 million on his 1995 tax records -- which, tax experts said, would have allowed Trump to avoid paying income taxes for a period of 18 years.
The paper did not look at his federal return. It obtained one page of his New York State resident income tax return as well as the first page of New Jersey and Connecticut nonresident returns.
CNN has not independently verified the documents' authenticity, but Trump's campaign has not challenged any of the facts reported by the Times.
Johnson told CNN's Fredrika Whitfield he was not aware what "loophole" Trump could have exploited to avoid taxes for so long and began to outline his own beliefs with regard to taxes.
"I do advocate eliminating income tax and corporate tax and replacing all of it with one federal consumption tax," Johnson said. "You could do away with the IRS."
While Trump said in a statement Saturday evening that he "knows the tax code far better than anyone who has ever run for President," Johnson said that for his part, "I'm very aware of taxes."
The Libertarian presidential nominee has struggled to convince voters he's prepared for the presidency, thanks to a series of high-profile stumbles. About a month ago, Johnson failed to recognize Aleppo, a city at the heart of the crisis in Syria, and earlier this week, he struggled to name a world leader he admired and eventually conceded he was having an "Aleppo moment."
On Saturday, the former New Mexico governor bemoaned that Clinton's demonstrated foreign policy knowledge helped legitimize her candidacy -- one he cast as trigger-happy and callous with regard to human life.
"What really angers me is that because you can dot the I's and cross the T's on geographic locations or the names of foreign leaders that we put our military in harm's way," Johnson said. "That's what angers me beyond belief ... That qualifies a person like Hillary Clinton to put our military in that crossfire? Have at it. Have at it."
Johnson also differed with his own running mate on Sunday by vouching for his own candidacy.
"We're the most qualified. Two former Republican governors," Johnson told CNN's Fredrika Whitfield.
Johnson was responding to his running mate Bill Weld's comments
on Friday in favor of Hillary Clinton.
Weld said he was "not sure anybody is more qualified than Hillary Clinton to be president of the United States."
"I think Gary is very, very solid," Weld added/
Johnson pointed out that Weld's praise of Clinton also came with criticism.
"Bill Weld went on to say that taxes are going to go up under Hillary," Johnson said.
Additionally, Johnson called Weld "the first one that raises questions" with regard to Clinton's controversial practices as secretary of state.