You will owe:
- a late-filing penalty if you do not file a return that we can process by the extended due date;
- a late-payment penalty for tax not paid by the original due date of the return;
- a late-payment penalty for underpayment of estimated tax if you were required to make estimated tax payments and failed to pay the required amount by the payment due dates;
- a bad check penalty if your remittance is not honored by your financial institution;
- a cost of collection fee if you do not pay the amount you owe within 30 days of the date printed on any IDOR-2-BILL, Final Notice of Tax Due for Form IL-1040, Individual Income Tax Return you receive;
- a frivolous return penalty if you file a return that does not contain information necessary to figure the correct tax or shows a substantially incorrect tax, because you are taking a frivolous position or are trying to delay or interfere with collection of the tax; and
- interest on unpaid tax from the day after the original due date of your return through the date you pay the tax.
We will bill you for penalties and interest. For more information about penalties and interest, see
Publication 103, Penalties and Interest for Illinois taxes.