Most, but not all, appeals to the Board of Tax Appeals must be filed within 30 days from the mailing date of the decision or determination being appealed.
Your deadline may be different, depending on the type of appeal. Deadlines for each appeal type are listed in WAC 456-09-315 and 456-10-315.
IMPORTANT: The Board has no authority to extend these deadlines or accept a late appeal. No ongoing discussions or extensions granted by the county board, Department of Revenue, or any other agency will extend your deadline with the Board of Tax Appeals.
Calculating an appeal deadline:
If the last day of the 30-day period (or other deadline period) falls on a Saturday, Sunday, or a legal holiday, the deadline period runs until the next day that is neither a Saturday, Sunday, or legal holiday. Remember – some months have more than 30 days. So, for example, an order or determination that is dated May 18 must be appealed to the WSBTA no later than June 17.
You may use the calculator below to calculate a 30 day appeal deadline..