Is the mere thought of Internal Revenue Service scrutiny enough to give you nightmares? For many Americans, it is. In a recent survey of more than 2,500 taxpayers, TaxAudit, the nation’s largest audit defense service, found that 47 percent feel anxious when they receive correspondence from the IRS. And while 65 percent are confident that their tax returns are error-free, 29 percent still worry the IRS will audit them.