For the last 40 years, every major presidential candidate has released personal tax returns. Before that, Richard Nixon released his tax returns -- even while he was being audited by the IRS. Donald Trump has been asked many times if he'll do the same.
What do voters learn from a presidential candidate's tax returns? When it comes to Donald Trump, we may never find out says David Cay Johnston, who won a Pulitzer Prize reporting on taxes for the New York Times. He's now a columnist for the Daily Beast, Investipedia and USA Today.