I’m in Maine, not New Hampshire but I worked remotely for a company based in Boston — they applied for a Maine tax ID and paid me with my Maine taxes withheld. You shouldn’t need to pay Massachusetts income tax if they set you up properly for remote work. Your taxes are based on where you physically sit while you work. When I used to occasionally travel to out of state offices, I’d have to file income taxes in multiple states. Once I had to file Connecticut income tax for spending three days in that office, because my company tracked it and listed multiple states on my W2.