35 ILCS 625/13
The Department may make, promulgate and enforce such reasonable rules and regulations relating to the administration and enforcement of this Act as may be deemed expedient.
Whenever notice to a taxpayer is required by this Act, such notice may be given by United States certified or registered mail, addressed to the taxpayer concerned at his last known address, and proof of such mailing shall be sufficient for the purposes of this Act. In the case of a notice of hearing, such notice shall be mailed not less than 7 days prior to the day fixed for the hearing.
All hearings provided for in this Act with respect to a taxpayer having his principal place of business in any of the several counties of this State shall be held in the county wherein the taxpayer has his principal place of business. If the 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 Act is begun by the Department or by a person subject thereto and such person thereafter dies or becomes incompetent before such proceeding is concluded, the legal representative of the deceased or incompetent person shall notify the Department of such death or incompetency. Such legal representative, as such, shall then be substituted by the Department for such person. Within 20 days after notice to the legal representative of the time fixed for that purpose, the proceeding may go forward in all respects and with like effect as though the person had not died or become incompetent.
35 ILCS 625/13