- 27September 27, 1840No events
- 28September 28, 1840No events
- 29September 29, 1840No events
- 30September 30, 1840No events
- 01October 1, 1840No events
- 02October 2, 1840No events
- 03October 3, 1840No events
A=ANNUAL
M=MONTHLY
Q=QUARTERLY
DISCLAIMER: THESE DUE DATES ARE SUBJECT TO CHANGE. WE WILL DO OUR BEST TO KEEP THIS CALENDAR UP TO DATE WITH THE EVERCHANGING DEADLINES. ANY STATE FILING DUE DATES ARE IN REFERENCE SPECIFICALLY TO THE WASHINGTON STATE DEPARTMENT OF REVENUE.