- 17February 17, 1980No events
- 18February 18, 1980No events
- 19February 19, 1980No events
- 20February 20, 1980No events
- 21February 21, 1980No events
- 22February 22, 1980No events
- 23February 23, 1980No 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.