There are significant losses in tax revenues across the European Union (EU). National governments lose billions of euros in the revenues from non-paid taxes and other illegal activities. The fight against aggressive tax planning, tax fraud and illegal activities is on the agenda of the EU, OECD and all the national governments. However, due to the size of tax losses it should not be treated just as tax evasion, but rather as tax terrorism! Therefore, the author has set criteria when tax evasion should be named as “tax terrorism” as well as designed the principles for tackling tax terrorism and other ways of non-payment of taxes. The tax evasion could be treated as “tax terrorism” in case of international evasion from taxes by organized groups of persons for criminal purposes as well as when it creates significant losses in government revenues. The term “tax terrorism” would have impact to communication and cause response of society and politics, therefore it would have more social and political consequences.