A service "system" implies a systematic strategy, design, implementation, operation, and evaluation of services. This systematic approach enables to more specifically define intrinsic problems of services and solve them. One of the problems involves time efficiency; it affects the quality of each service and, as a result, customer satisfaction. In other words, time efficiency has been one of the most critical factors in services' competitive power. Therefore, this paper recognizes the importance of time efficiency in a service system and then proposes the design of a time-aware service system which supports efficient service delivery and deployment. As for the complete design of service systems, the front and back stages should be considered together. This paper also addresses the time efficiency in terms of both the front and back stages. At the back stage, information for a time-aware service system is introduced and defined, and then the information is utilized in the front stage. Finally, the applicability of this paper is demonstrated through the example of the government agency service.