https://www.mass.gov/regulations/830-CMR-625a1-non-resident-income-tax#-3-income-subject-to-massachu... IS an excellent source about what is /isn't Mass source income.
https://www.mass.gov/service-details/learn-about-massachusetts-gross-income-for-nonresidents
**I don't work for TT. Just trying to help. All the best.
***Say "Thanks" by marking as BEST ANSWER and clicking the thumb icon in a post and that I solved your question
**Mark the post that answers your question by clicking on "Mark as Best Answer" I am NOT an expert and you should confirm with a tax expert.
