This is the great American tax filing week.

The IRS audited fewer corporations, small businesses and partnerships last year, but more individual taxpayers were checked, according to Syracuse University's Transactional Records Access Clearinghouse.

The IRS audited 14 percent more individual tax returns. The audit rate for individuals increased last year to 6.5 audits for every 1,000 taxpayers.

This is in a year when bigger tax breaks were given to the wealthiest Americans.

Researchers said the declining audits of businesses exposes a flaw in the administration's tough stance against corporate crime.

"These and a number of other measures — documented by the agency's own data — indicate that the actual performance of the IRS differs in significant ways from some of the Bush administration claims when it comes to cracking down on corporate scofflaws," according to the report.

"What struck me first was the commissioner earlier this week said that they'd increased enforcement and then I look at these numbers and say, 'What is he talking about?'" said David Keating for the National Taxpayers Union. "It really opens up a credibility gap."

Chellie Pingree, the president of Common Cause, a government watchdog group, said the study suggests corporations are not paying their fair share.