RCW 84.36.400 exempts from taxation any physical improvement to a detached single family dwelling for the three assessment years subsequent to the completion of the improvement, up to 30% of the value of the original structure. This can provide substantial tax savings for homeowners who remodel or expand their homes. This home improvement exemption may be claimed only once in a 5-year period. Normal maintenance work does not qualify for this exemption. Notice must be filed with the Assessor prior to completion of the improvement to claim the exemption.