If it is too late to appeal at your county board of equalization, you may be able to appeal either the valuation or for a refund of taxes paid as a result of an error in the assessment (lot valued at a larger size) at the state Board of Tax Appeals. I am not sure what the cutoff is there, or whether your situation satisfies the necessary grounds, but it is worth inquiring. http://bta.state.wa.us/
Participation on this board does create an attorney-client relationship. Only professional consultation and a mutual agreement for representation creates such a relationship. The foregoing is offered as general information only, and does not constitute legal advice. Please be advised you should consult a lawyer for advice specific to your situation.