This gets really messy for consulting companies, where employees "work" at the client location 3-4 days a week, 2-3 weeks a month.
We had to track and report what states we worked in and what days, down to the billing hours, and then in some cases had to file tax returns in some of those states.
Also, all of the partners were required to file taxes in every state where the company earned income, which worked out to something like 46 states and 5 countries.
Read up on the accounting required for baseball players. It's absolutely insane and sometimes comes down to "were they on the roster" or "in the stadium" or "on the lineup" and so forth.
This gets really messy for consulting companies, where employees "work" at the client location 3-4 days a week, 2-3 weeks a month.
We had to track and report what states we worked in and what days, down to the billing hours, and then in some cases had to file tax returns in some of those states.
Also, all of the partners were required to file taxes in every state where the company earned income, which worked out to something like 46 states and 5 countries.