Section 4-9-501 - Filing office(a) Except as otherwise provided in subsection (b) of this section, 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) 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.(c) The office in which to file an effective financing statement pursuant to article 9.5 of this title is the office of the secretary of state.L. 2001: Entire article R&RE, p. 1378, § 1, effective July 1.Colorado legislative change: Colorado added subsection (c).