A US person were living in Slovakia during 2023 and had earned income and self-employed income. The first one is from a foreign company located in Slovakia. The second is from a self- employed job with clients located in US. Slovakia and US has a Tax treaty and Social Security Totalization agreement. 

I would like to make sure that his self-employment income has to pay Social Security taxes in US due to that this income is not consider a foreign source of income. Can his services be consider performed in US while he is living abroad ? Also, the Totalization agreements says:  "Self-employed workers who normally work in the United States but transfer their business activity to Slovak Republic for five years or fewer are assigned U.S. coverage". I understand that this does not change the last understanding. 

Thanks,