The 2006 total gross state product for Illinois was nearly $589 billion USD, placing it 5th in the nation. The 2004 per capita income was $34,721 USD.

Illinois's state income tax is calculated by multiplying net income by a flat rate, currently 3%. There are two rates for state sales tax: 6.25% for general merchandise and 2% for qualifying food, drugs and medical appliances. The property tax is the largest single tax in Illinois, and is the major source of tax revenue for local government taxing districts. The property tax is a local�not state�tax, imposed by local government taxing districts which include counties, townships, municipalities, school districts, and special taxing districts. The property tax in Illinois is imposed only on real property.

Agricultural and industry

Illinois's agricultural outputs are corn, soybeans, hogs, cattle, dairy products, and wheat. In most years Illinois is the leading state for the production of soybeans, with a harvest of 500 million bushels (14 million metric tons) in 2004. Illinois is ranked second in total corn production. Illinois' universities are actively researching alternative agricultural products as alternative crops.

As of 2003, the leading manufacturing industries in Illinois, based upon value-added, were chemical manufacturing ($16.6 billion), food manufacturing ($14.4 billion), machinery manufacturing ($13.6 billion), fabricated metal products ($10.5 billion), plastics and rubber products ($6.8 billion), transportation equipment ($6.7 billion), and computer and electronic products ($6.4 billion). Important non-manufacturing industries include financial services, publishing, petroleum, and coal.