The development of state information systems, state electronic services, and electronic government systems require special approaches. However, at present, the requirements for the design notation of domestic state software are not defined and fixed. In the established practice, in the development of state software projects with a certain specificity and increased social significance, already existing technological solutions used in the private business are applied to the state information systems for various state departments of the Russian Federation. For the design of the state information systems and state e-services, it is suggested to use the unified methodology proposed by the authors, which includes subjects and objects, actions and processes, administrative restrictions, the IDEF0 standard, workflow class notation, the UML standard. The use of the proposed unified design methodology significantly structures, unifies and simplifies state software development. The advantages of using the proposed approach are illustrated in the implemented project to create a domestic customs inspection system.