“Totalization agreements” are formal agreements between the U.S. and foreign countries to avoid double taxation of income through social security taxes. The agreements only apply to the imposition of social security tax. If you are self-employed, your self-employment income is eligible for foreign earned income exclusions if you can satisfy the required conditions, but you are still subject to U.S. self-employment tax (i.e. social security tax). However, if you are residing in a country that has a totalization agreement with the U.S. and are subject to social security tax in that country on your self-employment income, you can be exempt from U.S. self-employment tax. There are over two dozen countries with signed agreements with the U.S.