03/22/2012 06:42 pm ET Updated May 22, 2012

IRS Audited More Multimillionaire Tax Returns In 2011 As Part Of Tax Evasion Crackdown

WASHINGTON, March 22 (Reuters) - U.S. tax officials are putting a closer microscope on the tax filings of multimillionaires, with the audit rate for those making more than $10 million a year jumping in 2011, according to newly released documents.

The Internal Revenue Service audited about 30 percent of the returns of those with adjusted gross income of $10 million or more in 2011, according to statistics released on Thursday. By contrast, in 2010, the agency audited about 18 percent of that group.

The tax service has cast a more skeptical eye on the wealthy in recent years, highlighted by its prosecution of the Swiss bank UBS AG and American taxpayers who attempt to avoid taxes by parking income abroad.

The audit rate also rose for those earning between $1 million and $5 million, to 12 percent in 2011, from about 7 percent in 2010.