35 ILCS 505/6
A distributor who sells or distributes any motor fuel, which he is required by Section 5 to report to the Department when filing a return, shall (except as hereinafter provided) collect at the time of such sale and distribution, the amount of tax imposed under this Act on all such motor fuel sold and distributed, and at the time of making a return, the distributor shall pay to the Department the amount so collected less a discount of 2% through June 30, 2003 and 1.75% thereafter which is allowed to reimburse the distributor for the expenses incurred in keeping records, preparing and filing returns, collecting and remitting the tax and supplying data to the Department on request, and shall also pay to the Department an amount equal to the amount that would be collectible as a tax in the event of a sale thereof on all such motor fuel used by said distributor during the period covered by the return. However, no payment shall be made based upon dyed diesel fuel used by the distributor for non-highway purposes. The discount shall only be applicable to the amount of tax payment which accompanies a return which is filed timely in accordance with Section 5 of this Act. In each subsequent sale of motor fuel on which the amount of tax imposed under this Act has been collected as provided in this Section, the amount so collected shall be added to the selling price, so that the amount of tax is paid ultimately by the user of the motor fuel. However, no collection or payment shall be made in the case of the sale or use of any motor fuel to the extent to which such sale or use of motor fuel may not, under the constitution and statutes of the United States, be made the subject of taxation by this State. A person whose license to act as a distributor of fuel has been revoked shall, at the time of making a return, also pay to the Department an amount equal to the amount that would be collectible as a tax in the event of a sale thereof on all motor fuel, which he is required by the second paragraph of Section 5 to report to the Department in making a return, and which he had on hand on the date on which the license was revoked, and with respect to which no tax had been previously paid under this Act.
A distributor may make tax free sales of motor fuel, with respect to which he is otherwise required to collect the tax, only as specified in the following items 1 through 7.
A specific notation is required on the invoice or sales slip covering such sales, and any supporting documentation that may be required by the Department must be obtained by the distributor. The distributor shall obtain and keep the supporting documentation in such form as the Department may require by rule.
For purposes of this item 7, a dyed diesel fuel dispensing facility is considered to have withdrawal facilities that are "not readily accessible to and not capable of dispensing dyed diesel fuel into the fuel supply tank of a motor vehicle" only if the dyed diesel fuel is delivered from: (i) a dispenser hose that is short enough so that it will not reach the fuel supply tank of a motor vehicle or (ii) a dispenser that is enclosed by a fence or other physical barrier so that a vehicle cannot pull alongside the dispenser to permit fueling.
All special fuel sold or used for non-highway purposes must have a dye added in accordance with Section 4d of this Law.
All suits or other proceedings brought for the purpose of recovering any taxes, interest or penalties due the State of Illinois under this Act may be maintained in the name of the Department.
35 ILCS 505/6