#1 Visit the website for Federation of Tax Administrators (www.taxadmin.org ) under the Taxpayers & Tax Preparers menu, use the State Tax Agencies link to go to the Illinois Department of Revenue website. Locate a copy of the Corporate Income and Replacement Tax Return (Form IL-1120), scrutinize Step 4, and describe how Illinoiss apportionment percentage is computed. Return to the FTA website and link to the Arkansas Department of Revenue website. Locate a copy of the Arkansas Corporation Income Tax Return (Form AR 1100 CT), scrutinize Schedule B, and describe how Arkansass apportionment percentage is computed.