- 15December 15, 1918No events
- 16December 16, 1918No events
- 17December 17, 1918No events
- 18December 18, 1918No events
- 19December 19, 1918No events
- 20December 20, 1918No events
- 21December 21, 1918No 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.