EN
This paper investigates the effects of legal solutions introduced to the VAT system in Poland in 2015–2019 to prevent VAT fraud, primarily carousel fraud, which caused the so-called tax gap. The article begins with chronological presentation of these solutions. In the second part the author formulates the criteria of certainty of business transactions in relation to VAT and on this basis he analyses the presented solutions. Next, he considers the costs incurred by the VAT payer to meet the obligations or requirements established by the introduced regulations. In the final section the effectiveness of the introduced solutions from the point of view of the state budget revenues from VAT is assessed.