Formal and informal sector in the economy have been defined in national statistics from different points of view: from the business, based on the number of employees; from the worker, if he is self-employed, being or not professional; from the work, by the contract condition. Although the concepts may be clear, when studying economic activities the borderline between the two sectors is fuzzy. A total 1,166 small businesses in 19 cities of Venezuela were surveyed. From the organizational relations established with the government and the market we obtained the definition of the formal and informal sector, in which we found an order of three types of informality.