How Trump devised his fake IRS audit excuse to 'get myself out of' releasing his taxes, according a new book

• Donald Trump invented his oft-repeated audit excuse for not releasing his tax records.
• "'I could just say, 'I'll release them when I'm no longer under audit,' Trump said,'" according to the book "Confidence Man."

Donald Trump invented his oft-repeated audit excuse for not releasing his taxes on the fly, while aboard his plane between campaign events as a 2016 presidential candidate.

Advisors were pressing Trump to deal with the issue and Hope Hicks, then the press secretary noted that every other candidate had released theirs and the pressure would increase, according to the newly released book "Confidence Man," by New York Times reporter Maggie Haberman.

Trump, looking at his former rival and then-advisor Chris Christie, said 2012 GOP presidential nominee Mitt Romney "made a huge mistake" by releasing his taxes, which showed him paying a relatively low effective rate.

"Trump thought for a second about how to 'get myself out of this,' as he said," Haberman wrote. "He leaned back, before snapping to a sudden thought. 'Well, you know, my taxes are under audit, I always get audited,' Trump said."

Haberman wrote that Christie "looked puzzled."

"'So what I mean is, well I could just say, 'I'll release them when I'm no longer under audit,' Trump said. 'Cause I'll never not be under audit.'"

Most major party nominees since Richard Nixon had released their taxes and there was no legal reason for Trump not to do so. Christie told Trump that the audit wouldn't prohibit their release.

But Trump said, "I'm sure my lawyers and my counsel will tell me not to.'" He began citing the claim "almost immediately" that he could not release his taxes, Haberman wrote.

The New York attorney general's office now investigating Trump's business practices has since filed a civil lawsuit against the former president, his three eldest children, and the Trump Organization. The suit alleges that Trump inflated his net worth and accuses the Trump Organization of artificially inflating or deflating asset values for loan and tax purposes.

The office has asked federal prosecutors to investigate.