A new book claims Donald Trump came up with his now infamous excuse for not releasing his tax returns literally on the fly—while on board his campaign plane in 2016 during the Republican primary. Although every president or nominee since Richard Nixon has released their tax returns, Trump refused to do so, arguing that he couldn’t because his taxes were under audit. According to journalist Maggie Haberman’s book Confidence Man: The Making of Donald Trump and the Breaking of America, Trump cooked up the excuse while discussing the obligation to release his taxes with then campaign manager Corey Lewandowski and then press secretary Hope Hicks. “Trump thought for a second about how to ‘get myself out of this’, as he said,” Haberman writes. “He leaned back, before snapping up to a sudden thought. ‘Well, you know my taxes are under audit. I always get audited,’ Trump said … ‘So what I mean is, well I could just say, ‘I’ll release them when I’m no longer under audit. ‘Cause I’ll never not be under audit.’”