According to requirements of the tariff legislation of the Russian Federation the accounting system of guaranteeing suppliers and energy service companies has to provide maintaining of the separate account on the allocated segments. The article presents the concept of the accounting system as the system for collecting, grouping and reporting of income and expenditure for each activity. The main problem of separate accounting in the electricity industry is the need for overhead allocation not only between the operational, but also between the realizable segments. As a version of solving the problem the author of the article offers a method of separate accounting for energy service companies. Objects of the accounting of expenses, operational and realizable business segments of activity are allocated; the main approaches to the organization of the separate account are described; the algorithm of the account and allocation of costs on energetically marketing activity is presented. The offered technique of multi-level distribution of indirect costs of guaranteeing suppliers will allow providing the requirements of the standard legislation, on the one hand, and creating more exact indicators of cost and productivity of activity in a section of the allocated segments.