35 ILCS 120/2e

Every such distributor or supplier shall deliver a statement of tax paid to each purchaser and the Department of Revenue not later than the 20th day of the month following the month during which a transaction occurred, showing: the number of gallons of motor fuel sold or distributed during the preceding month to that purchaser; identifying the purchaser to whom it was sold or distributed, including the purchaser's tax registration number; and the amount collected from the purchaser.