Tax lawyer and author Daniel Shaviro speculates on a number of issues that may be weighing on Romney, but one especially caught my attention,
3) It's been hard to understand what benefit he thought he was getting from the Swiss bank account, and there was an IRS amnesty program in 2009 for fraudulent nondisclosure of offshore income. If he had to come clean in 2009, this might be embarrassing, especially given that there was an iron fist inside the IRS leniency offer (i.e., if you held out, they might get you without any amnesty).Embarrassing indeed.
It's hard for me to believe that a man that has been planning a presidential run for at least 20 years would fraudulently hide income in a Swiss Bank account. Think what you want about Mitt Romney, but he's nobody's fool. On the other hand, it has only been in the last 5 or so years that Switzerland started to yield to outside pressure to cooperate with tax fraud investigations, and until this time it was widely believed that money could safely be stashed away in Swiss bank accounts without ever being found out. And Romney did close out the Swiss account in 2009, after his first formal run for POTUS
If I had to wager, I would not put any money on Romney having availed himself of IRS amnesty in closing out his Swiss account but it is food for thought.
I think the more likely reason(s) for Romney's reticence are years in which he paid little or no taxes based upon loss generating scams and very aggressive tax sheltering which Shaviro discusses in the above post. It's pretty clear at this point that Romney has a tin ear when it comes to political appearance of his income tax practices but it's quit another matter to knowingly hide off shore earnings from the IRS.