Who is require to withhold? • Withholding Agent.In order to file the IT-20SC, the Federal Form 1120 must be filed with the IRS. Register your business with the department via INBiz. A checklist of items you will need to register your business can be found in our BT-1 checklist. Foreign person, and pay the section 1446 withholding tax. Therefore, if you are a. Find information on taxes if you are an independent contractor doing business in the State of Indiana.