Donald Trump reportedly declared a $US916 million ($A1.2 billion) loss in 1995, a massive tax deduction that may have allowed him to avoid paying income tax for up to 18 years, reports are claiming.

Mr Trump’s personal financial circumstances has been a simmering sub plot of the presidential campaign, with the Republican refusing to release his tax returns, sparking claims from rivals that he has avoided paying taxes.

Even other Republicans have called for the nominee to release his tax details.

In response to the exclusive New York Times report, Mr Trump’s campaign team claimed the income tax document had been illegally obtained and that the newspaper was working to help rival Democratic nominee Hilary Clinton.

“Donald Trump is an extraordinarily successful private businessman who followed the law and created tens of thousands of jobs for Americans,” the statement read.

The report claimed the 1995 tax records showed how Mr Trump benefited from his diabolical financial deals in the early 1990s.

These included ill-fated Atlantic City casinos, a failed airline business and purchase of a Manhattan hotel.

The newspaper wrote that tax experts it hired to analyse Trump’s records said tax rules which are especially advantageous to wealthy filers would have let Trump use his $US916 million loss to legally cancel out an equivalent amount of taxable income over an 18-year period.

Although Mr Trump’s taxable income in subsequent years is as yet unknown, the loss in 1995 would have been large enough to wipe out more than $US50 million ($A65 million) a year in taxable income over 18 years, according to the report.

Mr Trump has repeatedly refused to release his tax records. This is despite previous candidates openly releasing theirs. He claims his taxes are under a federal audit.

During last week’s presidential debate, Ms Clinton accused Mr Trump of not paying any federal tax.

“That makes me smart,” Mr Trump replied. Watch Mr Trump’s full response on his taxes below:

Hillary Clinton: "Maybe" Donald Trump "doesn't want the American people … to know that he's paid nothing in federal taxes." #debates pic.twitter.com/KyWz4X0ch6

— PBS NewsHour (@NewsHour) September 27, 2016

Experts and the Internal Revenue Service (the US equivalent of the Australia Taxation Office), have said Mr Trump could still release them publicly if he wished.

“Mr Trump is a highly-skilled businessman who has a fiduciary responsibility to his business, his family and his employees to pay no more tax than legally required,” the Trump campaign statement said.

Mr Trump can seemingly say anything this campaign. Photo: Getty

“That being said, Mr Trump has paid hundreds of millions of dollars in property taxes, sales and excise taxes, real estate taxes, city taxes, state taxes, employee taxes and federal taxes, along with very substantial charitable contributions,” it said.

The taxes controversy is the latest media storm to plague Mr Trump during the marathon election campaign.

Despite each scandal – whether that be over alleged sexism, pro-gun comments or sledges toward an intellectually disabled reporter – Mr Trump is still very much a real prospect of becoming president.

The latest New York Times “average of the polls” poll has Mrs Clinton narrowly ahead of Mr Trump by three points. Americans will go to the polls on November 8 2016.

– with AAP