Can you comment on different models for international employees of a US startup who split time between their home country and USA?
It seems clear that they could come a few weeks a year to USA for training, meetings, etc. but coming for a year+ to do their work in USA clearly requires work authorization.
The frequency and duration of the trips can raise questions but in and of themselves aren't issues; what matters is the purpose of the trips, regardless of the duration; they must be limited to non-work/non-hands-on activities and the primary beneficiary of those activities must be entities or individuals outside the U.S. So it's possible to spend a lot of time in the U.S. as a visitor without crossing any line. But it's still important to be mindful of later repercussions even if no line is crossed; that is, if and when applying for a work visa, for example, an applicant might be questioned aggressively by a consular officer about the applicant's time in the U.S. as a visitor and might simply not believe that the applicant wasn't working if the applicant spent a lot of time in the U.S.
It seems clear that they could come a few weeks a year to USA for training, meetings, etc. but coming for a year+ to do their work in USA clearly requires work authorization.