Imposed on the privilege of earning or receiving income in or as a resident of Illinois. Individuals, estates, and trusts may be either residents or nonresidents.
Residents allocate all of their income to Illinois.
Nonresidents, including corporations, allocate certain types of nonbusiness income to Illinois and apportion their business income between Illinois and the other states in which they do business. Similar to federal income tax procedures, including withholding, declaration and payment of estimated tax. Credits against tax are permitted for residents for income taxes paid in other states. Special return requirements are imposed for withholding agents and persons making payments of estimated tax. Imposed on the privilege of earning or receiving income in or as a resident of Illinois.