35 ILCS 630/17
The Department may make, promulgate and enforce such reasonable rules and regulations relating to the administration and enforcement of this Article as may be deemed expedient.
Any informal rulings, opinions or letters issued by the Department in response to any inquiry or request for any opinion from any person regarding the coverage and applicability of this Article shall be maintained as a public record, and made available for public inspection and copying. If the informal ruling, opinion or letter contains trade secrets or other confidential information, where possible the Department shall delete such information prior to publication. Whenever such informal rulings, opinions or letters contain any policy of general applicability, the Department shall formulate and adopt such policy as a rule in accordance with the provisions of the Illinois Administrative Procedure Act.
Whenever notice to a retailer or taxpayer is required by this Article, such notice may be personally served or given by United States certified or registered mail, addressed to the retailer or taxpayer concerned at his last known address, and proof of such mailing shall be sufficient for the purposes of this Article. In the case of a notice of hearing, such notice shall be mailed not less than 7 days prior to the date fixed for the hearing.
All hearings provided for in this Article with respect to a retailer or taxpayer having his principal place of business in any of the several counties of this State shall be held in the county wherein the retailer or taxpayer has his principal place of business. If the retailer or taxpayer does not have his principal place of business in this State, such hearings shall be held in Sangamon County.
Whenever any proceeding provided by this Article has been begun by the Department or by a person subject thereto and such person thereafter dies or becomes a person under legal disability before the proceeding has been concluded, the legal representative of the deceased person or a person under legal disability shall notify the Department of such death or legal disability. The legal representative, as such, shall then be substituted by the Department in place of and for the person. Within 20 days after notice to the legal representative of the time fixed for that purpose, the proceeding may proceed in all respects and with like effect as though the person had not died or become a person under legal disability.
35 ILCS 630/17