It depends.

No - If you are efiling - you will not need to mail anything to the IRS or IL Department of Revenue unless you have a payment, then include the payment voucher with your payment check. You do not need to mail in either the tax returns or any additional documentation when filing your returns electronically.

Yes - If you are filing by mail, you will need to include all necessary attachments required for filing by mail. This will include copies of your W-2 and a copy of the federal return with your state return filing (it should be included with your print out of your state tax return). The filing instructions that print with your filing copy will include information about what additional documentation needs to be included with your file by mail copies (if any).