RCW 74.09.160: Presentment of charges by contractors.

Each vendor or group who has a contract and is rendering service to eligible persons as defined in this chapter or other applicable law shall submit such charges as agreed upon between the department or authority, as appropriate, and the individual or group no later than twelve months from the date of service. If the final charges are not presented within the twelve-month period, they shall not be a charge against the state. Said twelve-month period may also be extended by regulation, but only if required by applicable federal law or regulation, and to no more than the extension of time so required.