Oregon layers a Corporate Activity Tax on top of income tax and decouples its S-corporation deadline from its partnership deadline — a distinction the CPA calendar must reflect. It also has an elective PTE-E tax and notable Portland-area local income taxes.
Oregon Tax Deadlines at a Glance (2026)
Entity Type | Return Due | Extended Due Date |
|---|---|---|
Individuals (OR-40) | April 15, 2026 | October 15, 2026 |
C Corporations (OR-20) | May 15, 2026 | November 16, 2026 |
S Corporations (OR-20-S) | April 15, 2026 | October 15, 2026 |
Partnerships (OR-65) | March 16, 2026 | September 15, 2026 |
Oregon splits its business deadlines. Because Oregon corporate returns are due the month after the federal date, the S-corporation OR-20-S is due April 15, 2026 (not March 16), and the C-corporation OR-20 is due May 15. Partnerships (OR-65) follow the federal March 16, 2026 deadline. Don’t bundle S-corps and partnerships on one date — they diverge in Oregon.
The Corporate Activity Tax (CAT)
Beyond income tax, Oregon imposes a Corporate Activity Tax: $250 plus 0.57% of Oregon commercial activity above $1 million (after a 35% cost subtraction). Registration is triggered at $750,000 in Oregon commercial activity, and a return is required at $1 million. The annual CAT return is due April 15, with quarterly estimated payments — a separate obligation from the income/excise tax that CPAs must not overlook.
Rates and the PTE-E Tax
Oregon’s individual income tax is graduated to a 9.9% top rate; the corporate excise tax is 6.6% on the first $1 million and 7.6% above (with a $150 S-corp minimum). Oregon’s elective PTE-E tax is 9% on the first $250,000 of distributive proceeds and 9.9% above, elected annually on Form OR-21. CPAs advising Portland-area clients should also track the Metro Supportive Housing (1%) and Multnomah Preschool for All (1.5%+) local income taxes.
Estimates, Extensions, and Penalties
Individual estimated payments are due April 15, June 15, September 15, 2026, and January 15, 2027. Extensions cover filing only. The Oregon late-filing/late-payment penalty is 5% of unpaid tax, rising to 20% if unpaid more than three months; interest is set annually.
CPA Action Steps
File OR-20-S in April but OR-65 in March — Oregon splits these dates
Register for and file the CAT if Oregon commercial activity exceeds $750K/$1M
Consider the 9%/9.9% PTE-E election (Form OR-21)
Track Portland Metro SHS and Multnomah PFA local taxes
Verify current rates and dates against the Oregon Department of Revenue (oregon.gov/dor) before filing.