Where to file your taxes for Form 1120-S ; A foreign country or U.S. possession. 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. Form 2553 is the S corporation election document that a business entity must file with the IRS to elect passthrough taxation. Employee's Withholding Certificate Complete Form W-4 so that your employer can withhold the correct federal income tax from your pay. Enter the tax classification (C=C corporation, S=S corporation, P=Partnership).