What document must be filed to ensure perfection of a security interest?

To ensure perfection of a security interest, a financing statement must be filed. This document serves as a public notice of the secured party's interest in the collateral, thereby informing other potential creditors of the secured party's rights. Perfection is essential because it establishes the priority of the security interest in the event of bankruptcy or if the debtor defaults on obligations.

The financing statement typically includes the names of the debtor and the secured party, a description of the collateral, and is filed with the appropriate government office, usually a state-level filing office, to provide legal notice to third parties. By filing this document, a secured party can protect its interest in the collateral from competing claims.