Do I need to pay Social Security or FICA taxes if I run my own business overseas?

It will depend on how your company is structured and where you are located. If you are a sole proprietorship (i.e. no business entity) or have a US-based business entity, you will most likely need to pay US FICA taxes. This would be 15.3% of your income and would apply before you can use the Foreign Earned Income Exclusion, so you may have a cash expense. If you have a foreign-based business entity, you will probably not be liable for US Social Security or FICA taxes. However, if you are in a country that has a tax treaty with the US, you need to consult the tax treaty to see how and to whom these taxes would apply. Generally, these payments would need to be made quarterly throughout the year.