If no tax, penalty, or interest is due and no proceedings are pending to determine whether the taxpayer is indebted to the Department for tax, penalty, or interest, the credit memorandum or refund shall be issued to the taxpayer; or, the credit memorandum may be assigned by the taxpayer, subject to reasonable rules of the Department, to any other person who is subject to this Act, and the amount of the credit memorandum by the Department against any tax, penalty, or interest due or to become due under this Act from the assignee.
For any claim for credit or refund filed with the Department on or after each July 1, no amount erroneously paid more than 3 years before that July 1, shall be credited or refunded.
A claim for credit or refund shall be filed on a form provided by the Department. As soon as practicable after any claim for credit or refund is filed, the Department shall determine the amount of credit or refund to which the claimant is entitled and shall notify the claimant of that determination.
A claim for credit or refund shall be filed with the Department on the date it is received by the Department. Upon receipt of any claim for credit or refund filed under this Section, an officer or employee of the Department, authorized by the Director of Revenue to acknowledge receipt of such claims on behalf of the Department, shall deliver or mail to the claimant or his duly authorized agent, a written receipt, acknowledging that the claim has been filed with the Department, describing the claim in sufficient detail to identify it, and stating the date on which the claim was received by the Department. The written receipt shall be prima facie evidence that the Department received the claim described in the receipt and shall be prima facie evidence of the date when such claim was received by the Department. In the absence of a written receipt, the records of the Department as to whether a claim was received, or when the claim was received by the Department, shall be deemed to be prima facie correct in the event of any dispute between the claimant, or his legal representative, and the Department on these issues.
Any credit or refund that is allowed under this Article shall bear interest at the rate and in the manner specified in the Uniform Penalty and Interest Act.
If the Department determines that the claimant is entitled to a refund, the refund shall be made only from an appropriation to the Department for that purpose. If the amount appropriated is insufficient to pay claimants electing to receive a cash refund, the Department by rule or regulation shall first provide for the payment of refunds in hardship cases as defined by the Department.
35 ILCS 510/2