Though President Donald Trump insists he did nothing wrong on his taxes, experts say he could be on the hook for tens of millions of dollars in civil fines if state and federal authorities substantiate a New York Times report that found he and his family cheated the IRS for decades.

The statute of limitations for bringing criminal charges has long run out, but civil cases have no such limits, and the financial penalties could be staggering. Civil fraud charges for intentionally underpaying taxes, as the Times alleged the Trump family did, could include a penalty of up to 75 percent of the unpaid federal taxes and double the unpaid state amount, experts said.

The penalties "could be substantial, and if the allegations are proven in court, they should be levied," said Norman Eisen, chairman of Citizens for Responsibility and Ethics in Washington and former chief ethics counsel in the Obama administration.

The New York tax department said it is studying the Times' 15,000-word report and "vigorously pursuing all appropriate avenues of investigation." New York City also said it would investigate. A spokesman for the Internal Revenue Service declined to comment.

Trump tweeted that the newspaper did "a very old, boring and often told hit piece on me."

Donald Trump tweet

The White House dismissed the report as a "misleading attack against the Trump family by the failing New York Times," but spokeswoman Sarah Huckabee Sanders said the newspaper got one thing right: Trump's father not only did deals with his son but heaped praise on him by saying "everything he touched turned to gold."

A lawyer for Trump, Charles J. Harder, told the Times that there was no "fraud or tax evasion" and that parts of the report were "extremely inaccurate."

The Times said Trump received at least $413 million from his father over the decades, much of that through dubious tax maneuvers, including outright fraud. The report contradicts Trump's portrayal of himself as a self-made billionaire who started with just a $1 million loan from his father.