Creates the Illinois Renewable Fuel Standards Act. Provides that diesel fuel must contain at least a stated percentage of biodiesel fuel oil by volume on and after a specified date. Amends the Use Tax Act, the Service Use Tax Act, the Service Occupation Tax Act, and the Retailers' Occupation Tax Act. Makes changes concerning incentives for biodiesel to provide that the current exemptions for 100% biodiesel and biodiesel blends with more than 10% but no more than 99% biodiesel sunset on December 31, 2021. Provides that, with respect to 100% biodiesel and biodiesel blends with more than 20% but no more than 99% biodiesel, the taxes do not apply to proceeds of sales made on or after January 1, 2022 and on or before June 30, 2024 but apply 100% of the proceeds of sales made thereafter. Effective immediately, except that provisions creating the Illinois Renewable Fuel Standards Act take effect on July 1, 2021.