The article deals with the dependence of effective management of the subject of business on the accounting and analytical system that monitors, analyzes, controls the business activities of the company to make effective management decisions. The basic criteria of accounting information, stages of its transformation and classification features were examined. The basic requirements for accoun-ting information, including: relevance, reliability, completeness, relevance and absence of systematic errors. The regulation of accounting information depending on the level of its application is investigated and four stages of its obtaining are considered. The process of making management decisions based on the principle of "different costs for different purposes" has been studied. The essence of definitions "relevant costs", "irrelevant costs", "actual costs", "alternative costs", "fixed costs" and "variable costs" has been revealed. Based on a study of scholars' work on the relevance approach in management decision-making, two rules of relevance are summarised. The first is that the information presented to management must guarantee that the right management decision is made. The second ensures that the information is presented in an easy-to-understand format that does not contain redundant information. At the same time the essence of the concepts of "relevant information" and "irrelevant information" has been revealed. It has been established that relevant information is useful and appropriate for making management decisions while irrelevant information is past costs and part of future costs which will remain unchanged under different alternatives. Six sequential steps of the management decision making process were researched, which include: understanding the problem; defining criteria; identifying alternatives; developing a decision model; collecting data; and making a decision. It has been established that specialists in management accounting perform the functions of accountants-analysts (internal consultants) that provide internal users with the relevant information. The essence and toolkit of the analysis of the relevant information in the typical economic operations, in particular decision-making on: special order; structure of production (product range); manufacture of semi-finished products of own production or purchase them from outside; management in conditions of limited resources; expansion or reduction of enterprise activity has been researched.