Section 35 ILCS 405/15 - Circuit court jurisdiction and venue(a) Jurisdiction. Jurisdiction to hear and determine all disputes in relation to a tax arising under this Act shall be in the circuit court for the county having venue as determined under subsection (b) of this Section, and the circuit court first acquiring jurisdiction shall retain jurisdiction to the exclusion of every other circuit court.(b) Venue. (1) Venue for disputes involving Illinois estate tax of a decedent who was a resident of Illinois at the time of death shall lie in the circuit court for the county in which the decedent resided at death.(2) Venue for disputes involving Illinois generation-skipping tax for a resident trust shall lie in the circuit court for the county in which a person required to file the return is resident or, if none, in either Sangamon County or Cook County.(3) Venue for disputes involving Illinois estate tax of a decedent who was not a resident of Illinois at the time of death or for disputes involving Illinois generation-skipping tax of a non-resident trust shall lie in the circuit court for any Illinois county in which transferred property is situated.