30 ILCS 500/30-25
Whenever any contract entered into by a construction agency for the repair, remodeling, renovation, or construction of a building or structure, for the construction or maintenance of a highway, as those terms are defined in Article 2 of the Illinois Highway Code, for the construction or maintenance of facilities as that term is defined under Section 1-10 of the Illinois Power Agency Act, or for the reclamation of abandoned lands as those terms are defined in Article I of the Abandoned Mined Lands and Water Reclamation Act provides for the retention of a percentage of the contract price until final completion and acceptance of the work, upon the request of the contractor and with the approval of the construction agency the amount so retained may be deposited under a trust agreement with an Illinois bank or financial institution of the contractor's choice and subject to the approval of the construction agency. The contractor shall receive any interest on the deposited amount. Upon application by the contractor, the trust agreement must contain, at a minimum, the following provisions:
The trust agreement may, at the discretion of the construction agency and upon request of the contractor, become effective at the time of the first partial payment in accordance with existing statutes and rules.
30 ILCS 500/30-25