Oregon Revised Statutes Revenue and Taxation § 316.583

(1) Payment of the estimated income tax or any installment shall be considered payment on account of the income taxes imposed by this chapter for the taxable year.

(2) If there is an overpayment of income tax for a taxable year, the taxpayer may elect on a timely filed return for that taxable year (determined with regard to any extension of time for filing) to have the overpayment credited against an installment of estimated tax for the subsequent taxable year. The amount credited shall be deemed paid as estimated tax on the first date prescribed for payment of the estimated tax.

(3) If there is an overpayment of income taxes for a taxable year, and the taxpayer elects on a return (including an amended return) for that taxable year filed after the due date (determined with regard to any extension of time for filing) to have the overpayment credited against an installment of estimated tax for a subsequent taxable year, the overpayment shall be credited against that installment of estimated tax. The amount credited shall be deemed paid as estimated tax on the date the return was filed.

(4) The Department of Revenue may adopt rules which enable the taxpayer or department to credit against the estimated income tax the amount the taxpayer or the department determines to be an overpayment of the income tax for a preceding taxable year.