35 ILCS 200/20-40
When any person pays the taxes charged on any property, the collector shall enter the payment in his or her book, specifying by whom paid (if other than the assessee and if so requested), the amount paid, what year paid for, and the property and value thereof on which the same was paid, according to its description in the collector's books, and in case the tax was paid under protest, also that the tax was so paid. The entry and any receipt, if given, shall bear the genuine or facsimile signature or printed name of the collector or deputy receiving the payment. Evidence of payment shall consist of the taxpayer's cancelled check or money order and the receipt, where they exist, together with the entry in the collector's books. The collector or deputy shall be required to issue a receipt to a taxpayer only if (a) the taxpayer makes a payment in cash, or (b) the taxpayer requests a receipt as evidence of payment. If a taxpayer requests a receipt, the collector or deputy shall mail the receipt to the taxpayer. The collector shall enter, opposite each property, the name and post office address of the person paying the tax if that person is other than the assessee and has requested a receipt specifying by whom the tax was paid.
35 ILCS 200/20-40