Unless you are eligible for a waiver of overpayment, you are required to pay back any overpayments. To make an installment agreement, you will need to talk with IDES' Benefit Overpayment Collection at (800) 245-9762 (TDD (800) 662-3943).If you disagree with the determination you received, you have the right to file an appeal. If you were overpaid on unemployment benefits from the Illinois Department of Employment Security (IDES), you may not have to pay that money back. If you become unemployed, you may file a claim online at IDES.Illinois. Gov or at an IDES office.