Szara strefa – definicje, przyczyny, szacunki. Polska perspektywa zjawiska

The main objective of this article is to assess the causes and scope of activities preformed in the Polish informal economy with the focus on the small and medium-sized enterprises. It begins with the definitions and causes of the grey economy. Next, the author applies descriptive statistics to analyse the range of the scope of it Poland and selected countries. The research for the years 2010–2019 was conducted in an attempt to evaluate the phenomenon of tax fraud and qualitative methods of forecasting used to identify the opinions of Polish entrepreneurs regarding the extent of state budget’s losses due to the tax evasion.