The main goal of this article is to present the methods of effectively combating the grey area (called the shadow economy by the author) against the background of the changes introduced by the legislator in the form of split payment, as an institution that is to replace the not necessarily successful previous regulations related to reverse payment and joint and several liability. The first part — dealing with the grey economy — presents the basic facts on this topic. Attempts will be made to define this phenomenon, analyze its structure and the factors determining the formation of the shadow economy. This will be crowned with a multidimensional assessment, both in terms of micro and macroeconomics. The second part of the work will present split payment, which is to be a revolution in closing the tax gap. The tools that the split payment mechanism has “absorbed” due to their inefficiency will also be briefly discussed. Additionally, the article will present the history of this tool — both in the international arena and in Poland, where the optional form of split payment was initially in force, and currently, under certain conditions, it is also mandatory. The compulsory use of this tool is the subject of numerous discussions as it negatively affects the financial liquidity of entrepreneurs, which will also be analyzed and assessed. Taxpayers’ demands regarding changes in the split payment mechanism, especially in times of the COVID-19 pandemic, will also be presented. The dogmatic-legal and legal-comparative methods, as well as the opinions of the entrepreneurs themselves, will be used to achieve this research goal.