No, you must file a return. You can then subtract your retirement income off of your return. However, Illinois still wants to see the return. This is what Illinois Revenue's instructions say:

• a retired Illinois resident who filed a federal return, you must file Form IL-1040. However, certain types of retirement income ( e.g., pension, Social Security, railroad retirement, governmental deferred compensation) may be subtracted from your Illinois income. For more information, see the instructions for Line 5 and Publication 120, Retirement Income.