The U.S. Internal Revenue Service audited 8.36 percent of taxpayers reporting more than $1 million of income in fiscal 2010, the highest rate in the agency's recorded history.
The IRS said Wednesday that it conducted face-to-face audits of 16,509 millionaires and mail audits of 15,985 millionaires in the fiscal year that ended Sept. 30. That is an increase of almost 2 percentage points from 2009.
Overall, the IRS audit rate for individual returns reached 1.11 percent in fiscal 2010, the highest level in 10 years. U.S. taxpayers with incomes of less than $200,000 had an audit rate of 1.04 percent. The agency audited 3.1 percent of returns from taxpayers with annual incomes exceeding $200,000.