SUMMARY
Purpose of the article: This study describes the markets of payment instruments. It focuses mainly on the systems of credit and debit cards. Authors identify key moments in theory used in this dilemma, called Tourist Test. The market of credit cards and direct debit system is 4 side business, where the Interchange fee plays very important role.Methodology/methods: In this paper was applied secondary research. The secondary research was based on analysis of papers and literature published about Interchange fee including European Commission together with polemic about payment instruments market competitiveness.Scientific aim: The aim of this article is to identify the rules, conditions on the market of payment instruments - the system of credit cards and direct debit system. The authors try to recognize the problems on the demand and supply side. The authors focus on defying the cost-benefit approach, contributed with Tourist test. The Interchange Fee plays the key role.Findings: The approach of the scientific literature pays attention to costs and benefits, its equilibrium, also talking about social utility and social welfare the author is missing the whole impact on end consumer welfare and satisfaction. The dilemma is even more complicated due to the fact that the end consumer does not know he or she is not maximizing his or her utility, apart from the merchant, who is under pressure of margin squeeze.Conclusions: It is needed to start to measure the effectiveness and influence which the existence of Interchange Fee brings. Of course, confront the effectiveness and influence with benefits the Interchange Fee has.