Sources checked Oct. 14, 2026. Washington Tax Desk is independent of the Washington Department of Revenue (DOR) and is not a CPA or law firm.
Quick answer
Washington monthly excise returns are due the 25th of the following month, quarterly returns at the end of the month after the quarter, and annual returns on April 15 of the next year. When a due date falls on a weekend or legal holiday, DOR extends it to the next business day, so the Q3 2026 return listed for Oct. 31 (a Saturday) is due Monday, Nov. 2, 2026. DOR's 9% late penalty for Q3 2026 begins Nov. 3, 2026.
How DOR states the rules
- DOR: "Monthly returns are due the 25th of every month. (e.g. The June tax return is due July 25.)"
- DOR: "Quarterly returns are due the end of the month following the tax quarter."
- DOR: "Annual returns are due April 15."
- DOR: "If the due date falls on a weekend or legal holiday, the due date is extended to the next business day."
- Your filing frequency (monthly, quarterly or annual) is assigned by DOR. DOR says "Filing frequencies are assigned based on what you estimate for your yearly business income".
Important: DOR's 2026 excise return calendar lists the nominal due dates (for example, "Quarter 3, 2026 return Due date: 10/31/26"); it does not itself print the weekend-adjusted date. The "Next business day" column below is WTD's application of DOR's weekend/holiday rule, and it matches the "You must complete payment by" date on DOR's 2026 EFT calendar for ACH debit and My DOR users in every row.
2026 due-date table
Columns 2, 5, 6 and 7 are copied from DOR's 2026 excise tax return due-dates page. Column 4 is copied from DOR's 2026 EFT due-dates page (ACH debit & My DOR users: "Your payment must be completed by 11:59 p.m. Pacific Time").
| Return period | DOR listed due date | Day | ACH debit / My DOR: complete payment by | 9% penalty begins | 19% begins | 29% begins |
|---|---|---|---|---|---|---|
| January 2026 | 02/25/26 | Wed | 02/25/26 | 02/26/26 | 04/01/26 | 05/01/26 |
| February 2026 | 03/25/26 | Wed | 03/25/26 | 03/26/26 | 05/01/26 | 06/02/26 |
| March 2026 | 04/25/26 | Sat | 04/27/26 (Mon) | 04/28/26 | 06/02/26 | 07/01/26 |
| April 2026 | 05/25/26 | Mon (Memorial Day) | 05/26/26 (Tue) | 05/27/26 | 07/01/26 | 08/01/26 |
| May 2026 | 06/25/26 | Thu | 06/25/26 | 06/26/26 | 08/01/26 | 09/01/26 |
| June 2026 | 07/25/26 | Sat | 07/27/26 (Mon) | 07/28/26 | 09/01/26 | 10/01/26 |
| July 2026 | 08/25/26 | Tue | 08/25/26 | 08/26/26 | 10/01/26 | 11/03/26 |
| August 2026 | 09/25/26 | Fri | 09/25/26 | 09/26/26 | 11/03/26 | 12/01/26 |
| September 2026 | 10/25/26 | Sun | 10/26/26 (Mon) | 10/27/26 | 12/01/26 | 01/01/27 |
| October 2026 | 11/25/26 | Wed | 11/25/26 | 11/26/26 | 01/01/27 | 02/02/27 |
| November 2026 | 12/25/26 | Fri (Christmas) | 12/28/26 (Mon) | 12/29/26 | 02/02/27 | 03/02/27 |
| December 2026 | 01/25/27 | Mon | 01/25/27 | 01/26/27 | 03/02/27 | 04/01/27 |
| Quarter 1, 2026 (Jan–Mar) | 04/30/26 | Thu | 04/30/26 | 05/01/26 | 06/02/26 | 07/01/26 |
| Quarter 2, 2026 (Apr–Jun) | 07/31/26 | Fri | 07/31/26 | 08/01/26 | 09/01/26 | 10/01/26 |
| Quarter 3, 2026 (Jul–Sep) | 10/31/26 | Sat | 11/02/26 (Mon) | 11/03/26 | 12/01/26 | 01/01/27 |
| Quarter 4, 2026 (Oct–Dec) | 01/31/27 | Sun | 02/01/27 (Mon) | 02/02/27 | 03/02/27 | 04/01/27 |
| Annual 2026 | 04/15/27 | Thu | 04/15/27 | 04/16/27 | 06/02/27 | 07/01/27 |
| 2025 apportionment reconciliation (ARAI) | 10/31/26 | Sat | Safe date to file and pay: 10/30/26 (Fri) | — | — | — |
2025 periods paid in 2026 (DOR EFT calendar only): December 2025, complete payment by 01/26/26; Quarter 4, 2025, by 02/02/26; Annual (Jan–Dec) 2025, by 04/15/26.
Notes:
- DOR's EFT calendar also shows a second date, "Your payment due date is", one business day after the "complete payment by" date (for example 11/03/26 for Q3 2026). DOR doesn't explain the difference on the page, so this table uses the earlier date. To avoid penalties, pay by the "complete payment by" date.
- EFT credit users: DOR says funds must be "deposited in the state's bank no later than 5:00 p.m. Pacific Time on the payment due date," and your bank may set earlier cutoffs.
- Day-of-week and holiday labels are WTD's. All dates are from DOR.
- The 2025 apportionment reconciliation (ARAI) row is not from DOR's excise return or EFT calendars. DOR says the ARAI "is due by Oct. 31 of the following year," and Oct. 31, 2026 is a Saturday. To be safe, file and pay by Friday, Oct. 30. See our apportionment and annual reconciliation guide.
Late-payment penalties
DOR states: "The law requires DOR to assess a 9% late penalty if the tax due on a return filed by a taxpayer is not paid by the due date. Late penalties of 19 to 29% proceed as follows: 19% penalty due after the last day of the month following the return's due date; 29% penalty due after the last day of the second month following the return's due date." DOR adds: "The minimum penalty for late payment is $5." (RCW 82.32.090(1).)
DOR may waive late penalties only in limited cases: circumstances beyond your control, or once in a 24-month period if you filed and paid all required returns on time for the prior 24 months.
FAQ
When is the Washington Q3 2026 excise tax return due? DOR's calendar lists 10/31/26, which is a Saturday. Under DOR's weekend rule it moves to Monday, Nov. 2, 2026, and DOR's EFT calendar says ACH debit and My DOR payments must be completed by 11/02/26.
When are Washington monthly sales and B&O tax returns due? DOR says monthly returns "are due the 25th of every month" for the prior month, extended to the next business day if the 25th is a weekend or legal holiday.
When is the 2026 annual Washington excise return due? DOR's calendar lists April 15, 2027 (04/15/27), with the 9% penalty beginning 04/16/27.
What is the late penalty on a Washington excise tax return? 9% if not paid by the due date, rising to 19% and then 29% at the end of the next two months, with a $5 minimum (DOR; RCW 82.32.090(1)).
How do I know if I file monthly, quarterly or annually? DOR assigns your filing frequency based on your estimated yearly business income. Use the frequency DOR assigned to your account.
Sources
- DOR, 2026 Excise tax return due dates
- DOR, 2026 EFT due dates
- DOR, Filing frequencies & due dates
- DOR, Penalty waivers
- RCW 82.32.090
Have a question about your situation? Washington Tax Desk offers a free initial answer to one question, with reasoning and sources, reviewed by a person. If it helps, we can also suggest an optional referral; the referred professional may charge separately.
General information, not individualized tax advice. Results depend on the facts and applicable law. Washington Tax Desk is independent of Washington DOR.