Who can an organization contact with questions about charities and other nonprofit organizations? For answers to questions about charities and other non-profit organizations, an organization can call IRS Tax Exempt and Government Entities Customer Account Services at 877-829-5500 (toll-free number). An organization can also submit questions to: Internal Revenue Service Exempt Organizations Determinations P. O. Box 2508, Room 6-403 Cincinnati, OH 45201 Fax: 855-204-6184 For answers to employment tax questions, call the Business and Specialty Tax Line at 800-829-4933 (toll-free).