20 ILCS 2505/2505-510

(a) The Department has the power to establish an informal assessment review process at which an impartial Department designee, who has the authority and knowledge to recommend an appropriate conclusion to the matter, shall review adjustments recommended by examiners and auditors. The Director shall provide by rule for the availability of an informal assessment review before the issuance of a notice of tax liability or notice of deficiency upon completion of an audit of the taxpayer or before a formal hearing. A taxpayer may be represented by a party of his or her choice during the informal assessment review procedure and need not be represented by an attorney. (b) The exercise of this power to establish an informal assessment review procedure is mandatory, and the Director shall promulgate rules implementing this process within 180 days after the effective date of this amendatory Act of 1988. (c) Offers of disposition of a proposed audit adjustment may be proposed during the informal assessment review process. The panel shall consider disposing of the matter in controversy in all instances where, having made a reasonable evaluation of such matters, the panel determines that there is uncertainty as to the correctness of the proposed audit adjustments, and it is not in the best interest of the Department to issue an assessment or claim denial with respect to the issue due to, among other factors, potential hazards of litigation.