Oregon’s taxation system is distinct from many other states, combining the Corporate Activity Tax (CAT) with traditional corporate excise and income taxes. The CAT is a gross receipts tax applied to businesses with commercial activity in the state, while excise and income taxes target net income. Businesses ranging from C corporations and S corporations to partnerships, LLCs, and LLPs are subject to specific filing obligations, estimated tax rules, extensions, and penalties.
The CAT emphasizes registration and filing based on commercial activity thresholds, while excise and income taxes depend on income sources and business presence in Oregon. Minimum taxes apply in certain cases, and penalties for late filing or payment are strictly enforced. This blog provides a structured view of how Oregon taxes businesses across various categories, focusing on filing requirements, due dates, estimated payments, penalties, and extensions.
Corporate Activity Tax (CAT)
The CAT is imposed on businesses for the privilege of doing business in Oregon. It is measured by the total commercial activity realized from transactions in the regular course of business, without deductions for expenses.
Registration and Filing
- Businesses must register if Oregon commercial activity exceeds USD 750,000.
- If commercial activity reaches USD 1 million or more, businesses are required to file a CAT return.
- Registration must be completed within 30 days of meeting the threshold.
All businesses subject to the CAT must register with the Oregon Department of Revenue and file Form OR-CAT annually, even if no tax is due. The return must report the total commercial activity and compute tax liability.
Due Date
Returns are due by the 15th day of the fourth month following the end of the tax year.
Extension
A six-month extension can be requested using Form OR-CAT-EXT, but it must be filed before the original due date.
Estimated Tax Payments
Businesses with expected CAT liability of USD 5,000 or more must make quarterly estimated tax payments.
- Calendar year filers: April 30, July 31, October 31, and January 31
- Fiscal year filers: Last day of the 4th, 7th, and 10th months, plus the last day of the first month after year-end
Penalties and Interest
- Late payment: 5% penalty on unpaid tax, even if an extension is filed
- Late filing: 20% penalty if the return is filed more than three months after the due date and taxes remain unpaid
- Interest: 8% per year on unpaid tax from the original due date; increases to 12% per year if unpaid after 60 days
The penalty structure underscores the importance of timely filing and payment.
Corporate Excise and Income Tax (CET) for C corporation
Corporations doing business in Oregon, earning income from Oregon sources, or registered with the Secretary of State must file an Oregon corporate return.
Types of Taxes
- Excise tax: Applied to corporations doing business in Oregon, measured by net income, and subject to minimum tax.
- Income tax: Applied to corporations not doing business in Oregon but earning income from Oregon sources. Income tax filers are not subject to excise or minimum tax.
Corporate Excise Tax
Excise taxpayers are subject to a minimum tax based on Oregon sales:
| Oregon Sales (USD) | Minimum Tax (USD) |
| 500,000 – 999,999 | 500 |
| 1,000,000 – 1,999,999 | 1,000 |
| 2,000,000 – 2,999,999 | 1,500 |
| 3,000,000 – 4,999,999 | 2,000 |
| 5,000,000 – 6,999,999 | 4,000 |
| 7,000,000 – 9,999,999 | 7,500 |
| 10,000,000 – 24,999,999 | 15,000 |
| 25,000,000 – 49,999,999 | 30,000 |
| 50,000,000 – 74,999,999 | 50,000 |
| 75,000,000 – 99,999,999 | 75,000 |
| 100,000,000 and above | 100,000 |
This tiered system ensures larger corporations contribute more based on sales volume.
Corporate Income Tax
Corporations that are not doing business in Oregon but earn income from sources in the state are subject to income tax.
Tax Rates
- 6.6% on Oregon taxable income of USD 1 million or less
- 7.6% on income exceeding USD 1 million, plus USD 66,000
Due Date
Returns are generally due on the 15th day of the fourth month following the federal due date.
Filing Requirements
- Form OR-20: For corporations doing business in Oregon (excise tax filers)
- Form OR-20-INC: For corporations not doing business in Oregon but earning income from the state (income tax filers)
Extensions
- A federal extension allows for an Oregon extension if included with the Oregon return.
- Oregon-only extensions require Form 7004, marked “For Oregon Only,” attached to the Oregon return.
Estimated Tax Payments
C corporations must make estimated payments if their liability is USD 500 or more.
- Calendar year filers: April 15, June 15, September 15, December 15
Penalties and Interest
- Late payment: 5% penalty on unpaid tax
- Late filing: 20% penalty if the return is over three months late and taxes remain unpaid
- Interest: 8% per year on unpaid tax, starting from the original due date
Corporate Excise & Income Tax (CET) for S corporation
S corporations doing business in Oregon, with Oregon-source income, or registered with the Secretary of State must file an Oregon return.
Filing Details
- Form OR-20-S is required for S corporations.
- Tax rates mirror C corporations:
- 6.6% on income up to USD 1 million
- 7.6% on income above USD 1 million, plus USD 66,000
Due Date
Returns are due by the 15th day of the fourth month following the federal due date.
Extensions
- Federal extensions apply if attached.
- Oregon-only extensions require Form 7004, marked “For Oregon Only.”
Estimated Tax Payments
S corporations must make estimated payments if expected liability is USD 500 or more.
- Calendar year filers: April 15, June 15, September 15, December 15
- Fiscal year filers: 15th day of the 4th, 6th, 9th, and 12th months of the fiscal year
Penalties and Interest
- Late payment: 5% penalty
- Late filing: 20% penalty if more than three months overdue
- Interest: 8% annually, starting after the original due date
Corporate Excise and Income Tax (CET) for Partnership LLC & LLP
Partnerships, LLCs, and LLPs with Oregon-source income or registration with the Secretary of State must file returns.
Key Rules
- Partnerships must pay a USD 150 minimum tax if doing business in Oregon.
- Form OR-65 is used for partnership returns.
- Partnerships not required to file a federal return are also not required to file in Oregon.
Due Date
Returns are due by the 15th day of the third month after year-end.
Extensions
Federal extensions apply automatically. Oregon-only extensions grant the same six-month period as federal extensions.
Estimated Tax Payments
Partnerships, LLCs, and LLPs are not required to make estimated payments.
Penalties and Interest
- Non-filing: USD 50 per partner per month, up to five months
- Late payment: 5% penalty
- Interest: 8% per year, increasing to 10% if unpaid after 60 days
Conclusion
Oregon’s business tax structure is multifaceted. The Corporate Activity Tax (CAT) applies to gross receipts, requiring businesses to register and file once thresholds are met. Corporate excise and income taxes target corporations and impose minimum taxes for excise taxpayers, while income tax filers pay based on calculated liability. S corporations and partnerships have their own rules, extensions, and penalties.
Across all categories, Oregon enforces strict penalties and interest for late filing or payment, reinforcing compliance. Businesses operating in Oregon must carefully track thresholds, filing dates, and payment schedules to avoid costly mistakes and ensure proper compliance with state tax laws.
