Oregon Revised Statutes Revenue and Taxation § 308.875

If the manufactured structure and the land upon which the manufactured structure is situated are owned by the same person, the assessor shall assess the manufactured structure as real property. If the manufactured structure is owned separately and apart from the land upon which it is located, the assessor shall assess and tax the manufactured structure as personal property. A change in the property classification of a manufactured structure for ad valorem tax purposes does not change the property classification of the structure with respect to any transactions between the owner and security interest holders or other persons. Manufactured structures classified as personal property need not be returned under ORS 308.290.