86 Ill. Adm. Code 500.245
Estimated Claims
Section 500
Section 500.245 Estimated
Claims
The Department will approve
claims for refund of Motor Fuel Tax only when such claims are based upon a
showing that such motor fuel was used for a nontaxable purpose, and that the
part for which refund is claimed can, as a practical matter, be calculated and
itemized. When such claims are estimated or calculated, they must be supported
by verifiable documentation retained in the claimant's books and records. Only
claims which can be supported by proof of the amount of motor fuel not used for
a taxable purpose will be approved.