In accountancy, the account is the instrument that registers the summary record of a transaction or economic fact. Since the creation of the theory of double entry, by Fray Luca Pacioli in 1445, at least two accounts are used to record the accounting events. Due to the technological advancement, particularly with the accounting use of computerized information systems, the account code has become very important because this has become in the fundamental data that nourishes the computerized accounting system, and the content of accounting reports will depend on correct coding. In this sense, this codification must be done according to methodological criteria that guarantee financial reports with the accounting information on the economic period to which it refers. As a result of the present research, it is presented a series of guidelines to be implemented to structure the coding of accounts for SMEs which, when applied to the design of the catalog of accounts, will cover both the information needs and the correct reading and results issued by the different financial reports.