RCW 35.44.360: Assessments on omitted property—Authority.

If by reason of mistake, inadvertence, or for any cause, property in a local improvement district or utility local improvement district which except for its omission would have been subject to assessment has been omitted from the assessment roll, the city or town council, upon its own motion, or upon the application of the owner of any property in the district which has been assessed for the improvement, may proceed to assess the property so omitted in accordance with the benefits accruing to it by reason of the improvement in proportion to the assessments levied upon other property in the district.