Progressive taxation is a system where the tax rate changes based on how much money you make. In Russia, they recently switched to this system from a flat rate. This means that higher incomes will have a higher tax rate, while lower incomes will have lower or zero taxes. The goal is to make sure everyone pays a fair amount based on what they earn. This change is meant to address the issue of working poor in Russia. The researchers are looking at how this new system will work in Russia and what can be learned from other countries that already use progressive taxation.