Abstract: Underground economy, in view of researchers, economists and jurists, is a theoretical complex construct, a phenomenon with profound social and economic reverberations. This study argues multidisciplinary integrative the sociological, psychological and socio-psychological approach of underground economy. The premises of this study are given by methodological individualism and rational choice theory through building in neoclassical version of Homo economicus able to interact in a multidisciplinary and multifaceted manner with the area of social sciences.  For the nonce, we submit to analysis an integrative model of Homo Oeconimicus with Homo Sociologicus, aggregated with elements of social psychology.  Synergistic effects of this integrative approach consist of the ability to give an answer as relevant on symptoms and forms of deviant behavior and thus to explain the development of underground economy. The finality of this paper, starting from the stated premises, resides in the explanation and analysis of deviant behavior in the framework of the morphology and causality of underground economy. Deviant behavior in the context of our analysis reveals the coherence perspective on the following issues: anatomy and etiology of underground economy (informal and underground activities, illegal labor, tax fraud, etc.); attitude towards rules, society and the state (tax mentality, tax morality, moral conscience); tax compliance or non-compliance (willingness to pay tax liabilities). This paper is intended to constitute a pleading for an interdependent approach, multi-causal and interdisciplinary of underground economy.

Key words: Economics psychological; Economic sociology; Tax behavior; Tax morality; Underground economy.

JEL Classification: A12; Z13.