If you would like to have your overpayment credited to your future Illinois individual income taxes, complete Line 39. An overpayment may occur when a claimant is paid unemployment insurance benefits and is later found to not be eligible for those benefits.Complete the contact form page and attach a file for ONE of the following proofs of payment for each payment. Below is a list of forms and information that may be required to complete a Request for Proposal Response. Check out our Chicago style block quote examples. Tax Application and Affidavit Forms. Once completed, please submit the applicable form(s) below via email or mail to the address provided on the form. Use 1 inch margins or larger. The footnote number should be placed at the end of the sentence or the end of a clause in a sentence, after any punctuation.