Corporations file Schedule M-3 (Form 1120) to answer questions about their financial statements and reconcile financial statement net income (loss) You can get in-person help at your local IRS Taxpayer Assistance Center.Call for an appointment after you find a Taxpayer Assistance Center near you. Find out what takes place in the formation of a corporation and the resulting tax responsibilities and required forms. Find federal tax information for people starting a business, and information to assist in making basic business decisions. Trust our professionals to accurately prepare and file all legal documents necessary to register a business. This form is for general instructions that apply to all corporation tax forms. It includes a variety of topics about how to fill out your form.