Donald Trump's businesses made losses of more than £1 billion between 1985 and 1994, according to reports.
The New York Times said, based on tax information it acquired, Mr Trump appeared to have "lost more money than nearly any other individual American taxpayer".
It said he reported losses of $46.1 million in 1985 and a total of $1.17 billion for the 10-year period.
The Times said it acquired printouts from the President's official IRS tax transcripts.
It said these documents included figures from his federal tax form.
The paper also said, because of his business losses, he did not pay income taxes for eight of the 10 years.
The House Ways and Means Committee has asked the IRS to provide President Trump's personal and business returns for 2013 through 2018.
On Monday, Treasury Secretary Steven Mnuchin on Monday refused to do so.
He said the panel's request "lacks a legitimate legislative purpose",
This move, which had been expected, is likely to set a legal battle into motion and the chief options available to Democrats are to subpoena the IRS for the returns or to file a lawsuit.
Mr Trump is the first president since Watergate to decline to make his tax returns public.
The 72-year-old businessman turned politician has run an empire including hotels, casinos and golf courses.
He also previously touted his business skills as a host on the US version of The Apprentice and has written books including one titled 'The Art of the Deal'.
