WAT § 47400

The board shall levy an amendatory assessment in the manner provided for original assessments in Chapter 2 of this part if the original assessment was one levied pursuant to Chapter 2 of this part and any of the following occur:

(a) Any land within the district is omitted from any assessment roll.

(b) Land appears in the assessment roll but is neither assessed nor stated not to be assessed.

(c) A final judgment of a court of competent jurisdiction has held that any assessment is invalid as to any part of the land assessed.

This amendatory assessment shall be based upon a determination, as nearly as may be, of the amount the original assessment upon the land would have been except for the omission or invalidity.