From the May 11 edition of MSNBC’s The Rachel Maddow Show:
RACHEL MADDOW (HOST): Today, Mr. Trump told the AP he wouldn't release his tax returns before his current IRS audit is complete. When they asked him what would happen if that audit isn't concluded by November, Mr. Trump indicated to the AP that that would mean his tax returns wouldn't come out before November. His campaign defended that most of the day. They're now trying to portray it as a non-controversial decision. They've been trying to say that Mr. Trump somehow wouldn't be allowed to release his taxes because he was being audited. The IRS has clarified quite explicitly, though, that it doesn’t matter if you’re being audited, everybody is free to do whatever they want to do with their own financial information, including their tax returns. You shouldn’t feel constrained by the IRS at all. And we know from past precedent that even a sitting president who is currently being audited can release his or her taxes to the public if he or she wants to. President Nixon was being audited by the IRS while he was the sitting president, and he released his current tax returns during that audit. Ever since then, ever since Nixon, candidates have all released their taxes. And sometimes they’re slow about it or stingy about it. Sometimes they’re forthcoming. This year, if you so desire, you can read many, many, many, many, many years of Hillary Clinton's tax returns in full because they're posted online for the public to see.