Oregon Revised Statutes Revenue and Taxation § 311.515

Partial payments of taxes levied and charged on any property of at least $40 may be made at any time. Interest shall be charged and collected on each such partial payment at the rate provided in ORS 311.505 (2) from the due date of the particular installment of the taxes on which it applies. Each such partial payment shall be credited first to interest so accrued and penalties, if any, and then to principal of the taxes.