It is usually assumed that each user corporate network spends at least 80 working hours per year (10 working days, 2 weeks) on the self-study and on maintenance of the computer. But practice shows that this figure can easily increase a half to two times. Calculation of "indirect" costs of maintaining it infrastructure – a rather complicated thing. In order to take part tco methodology to take into account all of the above items, it is necessary to conduct a comprehensive audit of the enterprise information system. What should I look for in the first place? To audit the it infrastructure (detailed analysis) identifying with the bottlenecks (lack of reliability, availability or poor performance of certain components of the system, lack of backup, antivirus protection, corporate security systems information, etc.) Analyze all failures and delays that have occurred in the network for the selected period, focusing their attention to both the causes that led to the shutdown, and on actions to eliminate it. If the shutdown was planned (Routine maintenance, upgrade, etc.) – should determine whether the data reported in the pre-agreed plan, whether completed on time. If your organization has a centralized computer support services (Help Desk, or Service Desk) – to analyze the speed of the application for maintenance work and to find out the reasons for the delay in their execution. Generally speaking, the central office computer support should operate in international standards (ITIL and / or CobIT). Proper organization of such a service – key to high performance.