[pbhjpbhj]

I thought USA charged income taxes on dollar earnings paid in USA too.

That aside, suppose I work nomadically, ssh in to a computer in USA, perform actions there ... where is the work carried out? It's it necessarily the location of the employee? So USA based remote workers can geographically move to a low tax regime and save money? How about if I'm in USA working for an offshore company using a desktop and systems located in that companies premises but again I dial in to a USA based client; seems my work is offshore, at the companies premises?

[ska]

The answer to this is "it depends". This is really dependent on tax treaties and the nature of the work, it's as simple as where the computer is. The laws are basically set up to avoid setting up easy tax avoidance so it's not as simple as moving people around.