There's not much we've learned from the single tax return that Mitt Romney so generously released to the American people this week—but what we have learned is troubling.

To review: In addition to keeping significant sums of money invested in notorious offshore tax havens like the Cayman Islands and Luxembourg, Romney had $3 million in a Swiss bank account that he closed in 2010 for fear of political embarrassment. No one in the Romney camp has explained why Romney would have or need a Swiss bank account.

Today, the Los Angeles Times reported that Romney never disclosed the Swiss bank account or offshore investments in the personal financial disclosure form—required by all who run for federal office—he filed in August:

"A review by the Los Angeles Times/Tribune Washington Bureau found that at least 23 funds and partnerships listed in the couple’s 2010 tax returns did not show up or were not listed in the same fashion on Romney’s most recent financial disclosure, including 11 based in low-tax foreign countries such as Bermuda, the Cayman Islands and Luxembourg.

"Many of the undisclosed funds are affiliated with Bain Capital, the Boston-based private equity firm Romney ran for 15 years. Several others are apparently unrelated offshore entities with mysterious names such as Babson 2006-1, which is based in the Cayman Islands, and Barracuda Investments, which has an address in Dublin but appears to be solely owned by Golden Gate Capital, a private equity firm based in San Francisco."

Remember, Romney's main excuse for why he wasn't going to release his tax returns to the public was that his personal financial disclosure was sufficient. But when not one, not two, but at least 23 major items are conveniently missing from said personal financial disclosure, Romney's already dubious argument is utterly shot.

Romney continues to prove his willingness to hide critical information from the American public—which should be troubling to all voters, regardless of party. How can we trust him on his word alone? We're calling on Romney to reveal at least as many years of tax returns as his father, George Romney, did when he ran for president in 1968: 12 years. Add your name to join us in demanding basic transparency and accountability from Mitt Romney.