Section 810 ILCS 5/9-501 - Filing office(a) Filing offices. Except as otherwise provided in subsection (b), if the local law of this State governs perfection of a security interest or agricultural lien, the office in which to file a financing statement to perfect the security interest or agricultural lien is:(1) the office designated for the filing or recording of a record of a mortgage on the related real property, if:(A) the collateral is as-extracted collateral or timber to be cut; or(B) the financing statement is filed as a fixture filing and the collateral is goods that are or are to become fixtures; or(2) the office of the Secretary of State in all other cases, including a case in which the collateral is goods that are or are to become fixtures and the financing statement is not filed as a fixture filing.(b) Filing office for transmitting utilities. The office in which to file a financing statement to perfect a security interest in collateral, including fixtures, of a transmitting utility is the office of the Secretary of State. The financing statement also constitutes a fixture filing as to the collateral indicated in the financing statement which is or is to become fixtures. P.A. 91-357, eff. 7/29/1999; 91-357, eff. 7/29/1999; 91-893, eff. 7/1/2001.