If you do not receive a Schedule K-1-P, you should contact the partnership or S corporation and ask them to send you the information. You may wish to keep documentation of all attempts you make to obtain your K-1-P information.
If you do not receive the information by the original due date of your tax return, you may wish to take advantage of the six month automatic filing extension (seven months for corporations). However, if you will owe tax, you must file Form IL-505-I, Automatic Extension Payment for Individuals, or Form IL-505-B, Automatic Extension Payment for Businesses, and make any tax payment by the original due date of the tax return.
If you receive Schedule K-1-P information after you have filed an original tax return, you must file an amended return to include the pass-through income or loss.