The field of tax evasion has generally been the subject of research at different levels on a number of occasions. However, reality demonstrates that tax fraud today is far from being properly and completely perceived, so the mechanisms designed to prevent and combat it are far from being effective.Tax evasion is a very difficult concept to express, and there is no clear definition of tax fraud. When it comes to fraud, there is also talk of legal or legitimate fraud, illegal fraud, international evasion, legal and illegal evasion, tax havens or refugees, abuse of the right to flee to the tax, freedom to choose the least taxed way, or fiscal underestimation, law fraud or underground economy.