这两个页面都说nras are not subject to self-employment tax
而https://www.irs.gov/businesses/taxation-of-nonresident-aliens-1
这个页面又说Effectively connected income (ECI) is earned in the U.S. from the operation of a business in the U.S. or is personal service income earned in the U.S. (such as wages or self-employment income). It is taxed for a nonresident at the same graduated rates as for a U.S. person.