Where to file your taxes for Form 1120-S ; A foreign country or U.S. possession. Find out what takes place in the formation of a corporation and the resulting tax responsibilities and required forms.Once you know the name you want is available, you can file the appropriate forms for your business structure with the CA Secretary of State. Corporation. 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.