A Preliminary Change of Ownership Report (PCOR) is required whenever a document evidencing a change of ownership is recorded. If a PCOR is not received, the Assessor Department will mail you a Change of Ownership Statement (COS). The owner of the property is required to complete and return the form, under Section 480 of the Revenue and Taxation Code. Failure to file a completed COS within 90 days will result in a penalty bill of up to $5,000 for most residential properties.