A damning report in The New York Times on presidential hopeful Donald Trump, says that the tycoon declared a loss of more than $900m on his 1995 federal income tax return.
The report speculates that such a large loss may have enabled the Republican candidate to avoid paying tax for up to 18 years legally.
The newspaper says the report is based on three pages of documents which were sent last month to one of its reporters who had written about Trump’s finances.
During a heated presidential debate last Monday, Mrs Clinton said Trump’s refusal to release his tax returns, suggesting that he was hiding “something terrible”.
Trump responded by saying he would go against the advice of his lawyer and declare his tax returns if Mrs Clinton also published the content of some 3,000 emails allegedly deleted from her account.
Analysts say controversy around Trump’s tax returns could become a major bone of contention, especially since Mrs Clinton has publicly released nearly 40 years’ worth of her tax returns.
Significantly, every major US party presidential nominee has released tax returns since 1976.
On Saturday Trump’s campaign team accused the New York Times of being “an extension of the Clinton campaign”.