In 2009, President Obama unveiled a plan to catch tax evaders who hide their money in overseas tax havens*. The legislation, which eventually passed, is a complicated series of tax reforms, but the only thing we care about right now is a new IRS form called Form 8938. (Here is a PDF of the form. Here is a PDF of the instructions for the form.) This week, an anonymous Slog tipper—someone who is very knowledgeable about taxes—let me know that Form 8938 is going to cause a lot of trouble for Mitt Romney this fall, because it will require him to detail all the money he has in overseas accounts, at the risk of criminal penalty.

Let's step back a bit, to January of 2012, when the other Republican presidential candidates were hammering Mitt Romney for not releasing his tax returns. Finally, Romney released his returns for 2010 and an estimate for his 2011 returns, which he said weren't compete yet. Romney has said he will release the 2011 forms as soon as they're done, and he's filed for an extension which gives him until October 15th, about three weeks before the election. In the words of my source, part of the paperwork Romney will release on or before October 15th will include Form 8938, which requires Romney to "list the maximum value of each of his non-U.S. investments as part of his tax filings."

Previously, we have seen estimates of part of Romney's overseas fortune. But this form is more specific than what we've seen before, and it's more far-ranging, too. It requires taxpayers to include "Any financial account maintained by a foreign financial institution" and "any stock or securities issued by someone that is not a U.S. person, any interested in a foreign entity, and any financial instrument or contract with an issuer or counterparty that is not a U.S. person." Form 8938 will basically drive the news cycle for at least a week as reporters pick through every cent Romney has invested in offshore tax havens. Basically, it's going to be a very bad week to be Mitt Romney.

This raises a bunch of questions. The thing I don't understand is this: Why would Mitt Romney October Surprise himself like this? When he agreed to release his 2011 forms, did his campaign not understand the ramifications of Form 8938? Did they not even know the form existed? Do they not believe that there's anything controversial there? Will he try to dump the returns in August, or during the Olympics, when they believe nobody is paying attention? Or will they try to leave out some information when he releases his returns, as they did with his 2010 filings?

None of these questions have answers yet. But Form 8938 turns Romney's impending tax returns into a very specific threat to his own campaign; the information could be potentially more damning than anything we've seen before. The minute his returns are released, Form 8938 will be where everyone's eyes should focus.

*