Tax avoidance means neglecting to pay taxes that are owed. It is commonly practiced by multinational companies using tax havens to hide profits. While some tax avoidance has existed since the 1920s, it has grown significantly in recent decades, costing governments $50-200 billion in lost revenue annually. Poor countries have struggled to raise sufficient tax revenue due to tax competition between governments and trade liberalization policies that shift more of the tax burden onto poor individuals through consumption taxes. Tax havens undermine market competition and capital investment by allowing wealthy individuals and companies to escape taxation, and enable political corruption through secret bank accounts.