@madmanc20 --
"He will have a few business trips to NYS/NYC rest of the year for 1+ week per trip. He doesn't have to pay NYS/NYC taxes during these visiting periods."
That is not correct. NYS (but not NYC) can tax him as a non-resident on any income he earns from work he physically performs within NYS. He will have to keep track of the number of days he works in NYS so that he can correctly apportion his income at year's end. He will have to file a non-resident NYS tax return to report that income.
https://www.tax.ny.gov/pit/file/nonresident-faqs.htm#:~:text=As%20a%20resident%2C%20you%20pay,proper....
NYC income tax applies only to NYC residents.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
