RCW 84.68.010: Injunctions prohibited—Exceptions.

Injunctions and restraining orders shall not be issued or granted to restrain the collection of any tax or any part thereof, or the sale of any property for the nonpayment of any tax or part thereof, except in the following cases:

(1) Where the law under which the tax is imposed is void;

(2) Where the property upon which the tax is imposed is exempt from taxation; or

(3) Where the sale is a result of an error made by an officer or employee of the county, and the board of county commissioners or other legislative authority of the county issues an order.