Key Oregon Tax Deadlines (2026–27)

Every date here is for tax year 2026, filed in 2027. For every filing date in one place, including payroll, Washington-side and local business dates, use the tax deadline calendar. This list is about the cost of missing a date, not the complete schedule.

1. 15 April 2027: paying what you owe, extension or not

This is the most expensive date because people assume an extension covers it. It does not, federally or in Oregon. Oregon does not allow an extension of time to pay, even when the IRS grants one. Oregon charges a 5 percent penalty on tax unpaid after the April due date, plus interest. DOR’s annual interest rate for 2026 is 8 percent, and it rises by 4 percentage points, to 12 percent, if a DOR bill is not paid in full within 60 days. The federal failure-to-pay penalty is 0.5 percent of the unpaid tax per month, up to 25 percent.

If you cannot pay in full, filing on time and paying what you can still limits the damage. The IRS reduces its monthly failure-to-pay rate to 0.25 percent during an approved payment plan when the return was filed on time. See IRS payment plans.

2. 15 April 2027: the last day to claim a 2023 refund

A quiet deadline with a hard edge. Oregon refunds withholding and estimated payments only if the original return is filed within three years of its due date, not counting extensions. The 2023 return was due 15 April 2024, so an unfiled 2023 Oregon return with a refund due stops paying out after 15 April 2027. After that, the money cannot be refunded or applied to another year. The IRS has its own three-year limit on refund claims. If you have an unfiled year, the back taxes service is the place to start.

3. 15 January 2027 and the 2027 estimate dates

Freelancers, landlords and retirees without enough withholding pay quarterly. The fourth 2026 payment is due 15 January 2027; the 2027 payments follow on 15 April, 15 June and 15 September 2027. Oregon charges underpayment interest when your tax after credits and withholding is $1,000 or more and you paid less than 90 percent of the current year’s tax or 100 percent of the prior year’s. It is figured installment by installment, so a large December catch-up does not erase an April shortfall.

• Federally, higher earners use 110 percent of the prior year’s tax instead of 100 percent when 2025 AGI was over $150,000 ($75,000 married filing separately).
• The IRS lets you skip the 15 January 2027 payment if you file your 2026 return by 1 February 2027 and pay the full balance with it.
• More on setting the amounts: quarterly estimates.

4. 1 February 2027: W-2s and 1099-NECs

Employers must furnish 2026 W-2s to employees and file them with the Social Security Administration by 1 February 2027, because 31 January 2027 is a Sunday. Form 1099-NEC follows the same schedule. For payments made after 31 December 2025, the 1099-NEC and 1099-MISC reporting threshold is $2,000, well above the old threshold, so a business that issued forms by habit at the old level has a list worth rechecking before January. See 1099 contractors.

5. 15 March 2027: S-corporation and partnership returns

Pass-through returns (Forms 1120-S and 1065) are due on the 15th day of the third month after year end: 15 March 2027 for calendar-year entities. The cost of missing it spreads, because the owners cannot finish their own returns without the K-1s. Partnerships are required to furnish K-1s by the date they file, so a late entity return is a common reason an owner ends up extending a personal return. An extension is available for the entity return, but it extends filing only.

6. 15 April 2027: contributions that count for 2026

Some 2026 tax benefits can still be bought after the year ends, but only until the return’s original due date, with no extension:

• IRA contributions for 2026 can be made until the filing deadline, not including extensions.
• Oregon 529 and ABLE credits: 2026 contributions count until the date you file or the original due date, whichever is earlier. The 2026 credit is up to $190 ($380 married filing jointly), depending on AGI.

The trap is filing early. File on 10 February and a 529 contribution made on 1 March does not count for 2026.

7. 15 October 2027: extended individual returns

Oregon accepts a federal extension, and the extended return is due 15 October 2027. Oregon’s steep penalty starts three months after the due date, extensions included: a return filed after that point draws a 20 percent failure-to-file penalty, or 25 percent together with the failure-to-pay penalty. Three consecutive years of unfiled returns bring a 100 percent penalty on each year’s unpaid tax. Federally, the failure-to-file penalty is 5 percent of the unpaid tax per month, up to 25 percent, with a minimum for returns more than 60 days late. For returns required to be filed in 2027, which includes a 2026 return on extension, Rev. Proc. 2025-32 sets that minimum at $535 or the full tax due, whichever is less.

8. 15 April 2027: the Portland-area local personal taxes

Residents inside the relevant boundaries also file the Portland Arts Tax, Metro’s Supportive Housing Services tax and Multnomah County’s Preschool for All tax on the April date. The City of Portland’s Revenue Division administers all three. They are filed separately from the Oregon return, so they are easy to leave off.