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.

The Board has no authority to accept an appeal filed beyond these deadlines.

For determinations issued by the Department of Revenue: 

No ongoing discussions or extensions granted by the Department of Revenue 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. For example, May has 31 days, so for an order or determination that is dated May 18, an appeal must be made by June 17.

Use the calculator below to calculate a 30 day appeal deadline.