Audit fees paid by S&P 500 companies with more than $1 billion in annual revenue increased by “only” 3.2 percent in 2007 over audit costs in 2006, according to a study by Compliance Week magazine.

The increase in costs is down from the 4.4 percent increase from 2005 to 2006. Excluding a handful of companies with “extraordinary” transactions in 2007, the magazine said, the average audit fee in 2007 actually decreased 0.3 percent, indicating a stronger grasp of Sarbanes-Oxley requirements.

“This is evidence that the real growing pains of the Sarbanes-Oxley Act are now well behind us,” says Matt Kelly, editor in chief of Compliance Week. “Large companies now have four years of SOX compliance under their belts. Their major accounting weaknesses were rooted out years ago. The painful spikes in fee increases are over, and companies now appear to have a solid understanding of what their auditors want, and how to work with their auditors to keep costs down while complying with the law.”