RCW 35.50.050

An action to collect a local improvement assessment or any installment thereof or to enforce the lien thereof whether brought by the city or town, or by any person having the right to bring such action must be commenced within ten years after the assessment becomes delinquent or within ten years after the last installment becomes delinquent, if the assessment is payable in installments: PROVIDED, That the time during which payment of principal is deferred as to economically disadvantaged property owners as provided for in RCW 35.43.250 shall not be a part of the time limited for the commencement of action.