The tax audit rates of the largest companies are less than half what they were 20 years ago while more small and mid-size businesses are coming under scrutiny, according to an organization that monitors the Internal Revenue Service. The Syracuse University-based Transactional Records Access Clearinghouse described what it said was a historic collapse" in audits for corporations holding assets of $250 million or more. About 26 percent of them were audited in the 2007 budget year compared with 34 percent in 2006 and 43 percent in 2005. The IRS did not dispute the numbers, based on agency data. The TRAC report concluded that the IRS also was concentrating on regular small and mid-sized companies to boost audit numbers. "Moving the focus of the corporate auditors away from the large corporations and toward the smaller ones has been quite effective when it came to increasing the overall number of these kinds of audits but actually was counterproductive in financial terms," the researchers said. TRAC also questioned the financial benefits of the shift. The group said that last year the government uncovered $682 in additional recommended taxes for every revenue agent hour spent auditing the smallest corporations, compared with $7,498 in additional taxes for audits of the largest corporations. Dean Zerbe, national managing director for Houston-based alliantgroup, which provides tax services for medium-sized companies, said his fear was that "in the IRS' zeal to show Congress improved numbers in corporate audit, it is America's small and medium businesses that are taking it on the chin."