Republican presidential nominee Donald Trump speaks at a rally. Spencer Platt/Getty Images Donald Trump may have avoided paying federal income taxes for 18 years, according to tax records obtained by The New York Times and published on Saturday night.

The documents indicated that Trump declared a $916 million loss in 1995, providing him with a deduction so large it could have eliminated his obligation to legally pay annual federal taxes by up to $50 million for nearly two decades, tax experts told The Times.

Trump has refused calls to release his tax returns, a decades-old tradition every Republican nominee since Richard Nixon has followed.

At Monday night’s presidential debate, Clinton suggested Trump was perhaps refusing to publicly disclose his tax documents because he had not paid federal taxes. “That makes me smart,” Trump replied, raising eyebrows across the political world.

The Times said it had obtained the documents from an anonymous source who mailed the documents to its offices. The return address on the envelope was Trump Tower in New York City.

A lawyer for Trump, Marc E. Kasowitz, threatened The Times with “prompt initiation of appropriate legal action” if it published the documents.

The documents were published by The Times as Trump told a Pennsylvania crowd to “follow the money,” his latest line of attack against Hillary Clinton, in reference to his allegations she was engaged in a pay-to-play scandal while secretary of state.

The Trump campaign responded to the report by slamming The Times and trying to deflect to Clinton.

"The only news here is that the more than 20-year-old alleged tax document was illegally obtained, a further demonstration that the New York Times, like establishment media in general, is an extension of the Clinton Campaign, the Democratic Party and their global special interests," a campaign statement said.

It added: "What is happening now with the FBI and DOJ on Hillary Clinton's emails and illegal server, including her many lies and her lies to Congress are worse than what took place in the administration of Richard Nixon - and far more illegal."

Clinton's campaign pounced on the report. Campaign manager Robby Mook said in a statement late Saturday that the "bombshell report" revealed the "colossal nature of Donald Trump's past business failures and just how long he may have avoided paying any federal income taxes whatsoever."

Editor's note: This story has been updated to include comment from the Trump and Clinton campaigns.