For three years, the Internal Revenue Service has been stepping up its oversight of taxpayers who report more than $10 million in income. In 2011, the IRS audited almost 30 percent of them.
While the percentage of individuals audited overall has held steady at 1.1 percent for the past few years, the rate has been climbing for the ultrarich. In 2010, 18 percent were audited, up from 10.6 percent in 2009, according to an IRS report.
The IRS created a special unit in 2009 to examine the tax returns of the wealthy after nearly 15,000 Americans with offshore bank accounts voluntarily came forward to avoid prosecution for tax evasion.