505 ILCS 145/75
A producer who has sold wheat and has an assessment deducted from the sale price may, by application in writing to the board, secure a refund in the amount deducted. The refund shall be payable only if the application has been made to the board within 90 days after the deduction. Interest shall be allowed and paid at the rate of 6% per annum upon the total amount of the assessment imposed by this Act, except that if any assessment is refunded within 90 days after an application for refund has been made within the required 60 days after deduction or within 90 days after the first purchaser of wheat remits the assessments withheld and deducted to the wheat development board, whichever is later, no interest shall be allowed on such assessment. An application for refund by a producer shall provide proof of assessment deducted.
505 ILCS 145/75