More tax returns from corporations and wealthy taxpayers were audited by Internal Revenue Service examiners this year, helping the agency haul in a record $47.3 billion in unpaid taxes.

IRS Commissioner Mark W. Everson said the audit rate of high-income individuals and families, those who report earning $100,000 or more, is "still too low."

"I haven't set a specific target," Everson said. "Our No. 1 area of emphasis has been to increase our work in high-income individuals and corporations. We do that because of the sense of fairness that resonates throughout the rest of the system."

The IRS audited one in 63 wealthy individuals and families, the highest rate in 10 years, the agency said. By comparison, about one in 117 taxpayers who made less than $100,000 were audited. Overall, about one of every 107 individuals faced an audit, more than last year, when the tax returns of about one in 129 taxpayers were examined.

The record amount collected this year includes nearly $4 billion from a settlement with taxpayers who used a tax shelter designed to hide unusually large income gains.

Audits of corporations and small businesses also climbed compared with last year. An average of 20 percent of corporations were audited during the fiscal year that ended Sept. 30. The largest of those, with assets of $250 million or more, faced the highest audit rate, about 44 percent.

The number of small businesses that faced an audit also rose after a significant dip last year. About one in 126 small businesses, those with assets of less than $10 million, were audited this year.

The IRS released the statistics while emphasizing that the gains were not made at the expense of customer service. IRS customer satisfaction, as measured by a private contractor, was 95 percent.