Offshore tax shelter? Check. Income hidden from tax authorities? Check. New IRS unit specifically set up to target taxpayers with tens of millions of dollars? Check.

IRS Commissioner Doug Shulman told the American Institute of Certified Public Accountants Monday that the agency has set up a unit specifically to deal with rich Americans who are hiding assets.

"We will take a unified look at the entire web of business entities controlled by a high-wealth individual," Shulman said. "At least initially, we will be looking at individuals with tens of millions of dollars of assets or income."

"The high-wealth unit will focus on trusts, real estate investments, privately held companies and other business entities controlled by rich individuals. While use of sophisticated legal structures are at times legal, there are other instances where they 'mask aggressive tax strategies,' he said."