305 ILCS 5/11-14
A recipient or former recipient of financial aid under this Code, or a responsible relative or other person in behalf of the recipient or former recipient may voluntarily repay all or part of the financial aid rendered to him and in respect to which repayment was not required by this Code or other laws of this State.
Repayments may be made to the County Department or to the local governmental unit which rendered the financial aid. If there is more than one such local governmental unit, the repayment may be made to any one of such governmental units and the local governmental unit to which the repayment is made shall transmit to the other unit or units a proportionate share of the repayment which shall be in the ratio of the assistance rendered by each unit to the total assistance rendered by all units.
The fact of such voluntary repayment and the amount thereof shall be duly entered on the public aid disbursement record, and in the case record of the recipient if available, and designated in such manner as will clearly distinguish such repayment as made voluntarily and without compulsion.
Voluntary repayments to County Departments shall be paid into the general fund in the State Treasury, or into such other fund as may be established by law for such voluntary repayments. Repayments to local governmental units shall be paid into the general assistance fund of the governmental unit or other special fund into which general assistance moneys of the local governmental unit are paid.
305 ILCS 5/11-14