30 ILCS 230/2a.1
Payment of money under protest to every officer, board, commission, commissioner, department, institute, arm or agency authorized to receive moneys for or on behalf of the State shall be noted by the payer as paid under protest as to each payment so made. In cases where a single remittance is made of an amount of money in excess of that so paid under protest, the particular amount paid under protest together with pertinent data descriptive of the suit or suits in relation to which such payment or payments are made and the amount allocable to each, shall be stated.
Notice of payment under protest shall be made in substantially the following form:
(Date)..... To: (Officer, board, etc., to whom payment is made). You will please take notice that $.... of the attached or enclosed remittance in the amount of $.... for (Motor Fuel Tax, Retailers' Occupation Tax, Franchise Tax, etc., as the case may be) is made under protest. The undersigned is an original (or intervening) party plaintiff in the following case or cases in relation to which the aforesaid payment is made under protest. (Here list title of case or cases, the court in which pending, and the general court number assigned to each. If more than one suit is pending, the specific amount paid under protest as to each case shall be stated by the person making payment under protest.) .... (Name of person making payment under protest.) ....(Address) By .... (Authorized officer or agent.)
30 ILCS 230/2a.1