Oregon computes taxable income for subchapter C corporations by starting with federal taxable income and then modifying that based on Oregon’s tax law.
Corporations doing business in Oregon are required to file Form OR-20, Oregon Corporation Excise Tax Return.
Corporations not doing business in Oregon, but with income from an Oregon source, are required to file Form OR-20-INC, Oregon Corporation Income Tax Return. If you have tangible or intangible property or other assets being used in Oregon, any income you receive is Oregon-source income.
"Doing business" means being engaged in profit-seeking activities in Oregon that aren’t protected by Public Law 86-272. If the corporation has an Oregon address, generally the corporation will file and pay excise tax. A corporation having one or more of the following in this state is doing business in Oregon:
  • A stock of goods.
  • An office.
  • A place of business (other than an office) where corporation affairs are regularly conducted.
  • Employees or representatives providing services to customers as the primary business activity (such as accounting or personal services), or services incidental to the sale of tangible or intangible personal property (such as installation, inspection, maintenance, warranty, or repair of a product).
  • An economic presence through which the taxpayer regularly takes advantage of Oregon's economy to produce income.

Excise tax

Excise tax is a tax for the privilege of doing business in Oregon. It is measured by net income. All interest is included in income, no matter its source.

Minimum tax

Excise tax filers are subject to a minimum tax. This minimum tax is not subject to the state tax add back provision for Oregon corporations filing Form OR-20 or Form OR-20-S (ORS 317.314).

Filing information

All returns are due on or before the 15th day of the month following the due date of your federal corporation return (May 15 for calendar-year taxpayers). When the 15th falls on a Saturday, Sunday, or legal holiday, the due date is the next business day.
If you are a multistate corporation with income from two or more states, you’ll need to apportion, and possibly allocate, your income. For more information, see the instructions for Schedule OR-AP, Apportionment of Income for Corporations and Partnerships.

Federal audit changes

If the IRS changes your federal return for any tax year, you must notify us. File an amended Oregon return and attach a copy of the federal audit report. Mail this separately from your current year's return.

Mail tax-due returns to:
Oregon Department of Revenue
PO Box 14790
Salem OR 97309-0470
Mail refund or no tax-due returns to:
Oregon Department of Revenue
PO Box 14777
Salem OR 97309-0960
If you don’t amend or send a copy of the federal report, we have two years from the date the IRS notifies us of the change to issue a deficiency notice. You must file an amended return within two years of the date of the federal report to receive a refund.