This paper aims to assess the future of CAP reforms after 2020 in Poland. We provide a comparative analysis in which the impact of uniform and coupled support scenarios are assessed and compared against alternative environmental regulation measures. An agricultural supply model AROPAj is used to highlight the difference between scenarios. Coupled support for protein and legume crops reduces inequality between farm groups. Although crop diversification increases, no drastic land use change has been noticed, thereby reducing N-fertiliser use and GHG emissions. Results vary according to regions and the type of farming and economic size.