In return for tax-exempt status, federal law requires nonprofit health systems to help the poor and also provide community benefits to the general public. But exactly how much help they have to provide is unclear. The Internal Revenue Service has taken a permissive stance, requiring such entities to list their for-profit affiliates but not limiting the number or size of these affiliated companies. But critics suggest that Ascension and other nonprofit health systems are for-profits in disguise. "The modern health care organization is not any more charitable than Google or Microsoft Corp. or Yahoo," said John Colombo, a professor at the University of Illinois College of Law and expert on tax-exempt organizations.