- 16December 16, 1979No events
- 17December 17, 1979No events
- 18December 18, 1979No events
- 19December 19, 1979No events
- 20December 20, 1979No events
- 21December 21, 1979No events
- 22December 22, 1979No 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.