Oregon Revised Statutes Revenue and Taxation § 311.275

As between the grantor and the grantee of real property or the buyer and seller of personal property, when there is no express agreement as to payment of the taxes on the property becoming due and payable for the fiscal year in which the sale occurs, the grantor or seller is liable for the same proportion of the taxes as the part of the fiscal year prior to the day of the sale of the property bears to the whole of the fiscal year, and the grantee or buyer is liable for the remainder of the taxes.