- 28December 28, 1800No events
- 29December 29, 1800No events
- 30December 30, 1800No events
- 31December 31, 1800No events
- 01January 1, 1801No events
- 02January 2, 1801No events
- 03January 3, 1801No 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.