Thanks for your reply Diane,
Yes, I understand @ErnieS0 's advice for my own situation and I will file this income personally (likely through an expert) but I am still not clear if my work counts as "doing business in the US" from the perspective of my UK employer and if they would have to file.
The 26 CFR § 1.864-4 - U.S. source income effectively connected with U.S. business is very confusing. The company does not have a physical entity yet set up in the US.
Thanks
