The IRS is going after bigger game among individuals, too, she noted. One agent told her that a high-wealth group formed by the service almost two years ago currently is "focusing on returns that are two-to-three inches thick; in other words, taxpayers with a lot of investments."

In learning about such high-income taxpayers, the IRS is eager to explore the webs of assets available to them, she said, using link analysis tools to unravel the "tentacles" that spread out from entities such as trusts and multi-tiered partnerships.

There is also continuing effort to review more returns of flow-through entities, according to Katz-Pearlman. "In time of flat budgets, the IRS cannot increase activity across the board, but must address areas where there is growth and potential risk," she said.

"The theme of all this is 'the IRS is coming, the IRS is coming'," said Brian Trauman, national principal-in-charge of KPMG's Transfer Pricing Dispute Resolution Services. " But we've been saying that for a while."