Washington Return of Service (ROS) is a process that requires service providers to provide documentation of service to individuals or businesses within the state of Washington. This process is used to ensure that individuals and businesses in the state are properly served with legal documents, such as lawsuits, subpoenas, and court orders. There are two types of Washington Return of Service: voluntary and mandatory. Voluntary ROS requires a service provider to file a form with the court, acknowledging that service has been made. Mandatory ROS requires service providers to file a return of service form with the court, which includes a sworn statement that service has been made. In both cases, the court will review the form and determine whether service was made in accordance with the rules and regulations of the state. If the court finds that service has been made, a certificate of service will be issued and the process is complete. If the court finds that service has not been made, the process must be restarted, and the service provider must provide additional evidence of service to the court.