His firm specializes in tax and accounting for nonprofits and small businesses. Most of his clients are nonprofits who use QuickBooks®. Since 2000, Gregg has been teaching QuickBooks® seminars around the country for various groups and is considered to be an expert in the program. He has taught both new users as well as other CPAs, who are themselves considered experts in the software. Gregg has taught for Intuit, the makers of QuickBooks, teaching CPAs around the country the new features in updated versions of the software. Gregg also teaches annually at the Scaling New Heights Conference, presently the largest gathering of QuickBooks Proadvisors in the world. In total, Gregg has taught over 1500 seminars to more than 35,000 students.