- 26December 26, 1819No events
- 27December 27, 1819No events
- 28December 28, 1819No events
- 29December 29, 1819No events
- 30December 30, 1819No events
- 31December 31, 1819No events
- 01January 1, 1820No 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.