WASHINGTON (Bloomberg) The Internal Revenue Service announced that 12,000 taxpayers have declared offshore bank accounts in the second round of a voluntary disclosure program that the agency says has yielded $2.7 billion overall.IRS Commissioner Douglas Shulman said today that the agency’s emphasis on international tax enforcement prompted more people than anticipated to accept penalties and reveal accounts.“The results we’re seeing today were unthinkable just a few short years ago,” he said on a conference call with reporters. “The world has clearly changed.”The results mark the continuation of the IRS’s beefed-up enforcement efforts, which include the voluntary programmes as well as prosecutions with the Department of Justice.“You’d have to be living in a hole not to know that the US government is really focused on offshore tax evasion, getting better at it,” Shulman said.He declined to comment about US efforts to obtain account information from Swiss banks, other than to confirm that the US and Swiss governments are discussing the issue.“This effort was never about Switzerland,” Shulman said. “I think a lot of Swiss banks aren’t taking these kinds of accounts anymore and they’re really trying hard to move forward.”In 2009, the US and UBS AG reached a deferred-prosecution agreement under which the bank paid $780 million. Since then, the US has been prosecuting clients of UBS, HSBC Holdings Plc and other banks around the world.The voluntary programme allowed US taxpayers with offshore accounts to come forward and pay back taxes and penalties to likely avoid prosecution.The programme’s initial round in 2009 yielded $2.2 billion in taxes, interest and penalties from 15,000 taxpayers, Shulman announced yesterday.An additional 3,000 taxpayers came forward after that programme ended, and 12,000 declared accounts this year under the 2011 programme, which had a deadline of September 9 and less generous terms for taxpayers than the previous version.“This is a much bigger number than any of us thought we’d ever get in this programme,” Shulman said.Shulman said the 2011 programme has yielded $500 million so far, and he expects that to increase because the total so far doesn’t include many penalties.He said he didn’t have data yet about the average size of accounts declared in 2011 or their geographic composition.