Illinois Tax Extension
The state tax returns for residents of the Prairie State are due by April 15 (for calendar year filers).
However, If you can't squeeze it in by that deadline, the Illinois Department of Revenue will grant you an automatic six-month extension of time to file. A tax extension extends your filing due date to Oct. 15.
If you've gotten a federal tax extension, you'll automatically get an Illinois tax extension as well, so there's no need to submit an extra application.
Keep in mind that this is an extension of time to file, not an extension of time to pay the income tax due. You're still required to pay any tax you owe by the original filing deadline (April 15) to avoid incurring penalties and interest charges. If you owe state income tax, you must submit Illinois Tax Form IL-505-I (Automatic Extension Payment for Individuals Filing Form IL-1040) with your payment by April 15, 2013. Remember, this form should only be used if you are making a state tax payment by paper check or money order (electronic payments can be made online).
Mail Form IL-505-I, with payment, to:
Illinois Department of Revenue, PO Box 19005, Springfield, Illinois 62794-9005
Here are some online resources for residents of The Prairie State:
>> The following is a list that we've compiled of tax extension rules by states.