To which state do I owe tax from the sale of some ISO stock options?

Q: I live in New Hampshire, and this past year my job moved to Massachusetts. I did a same day sale of some ISO stock options while employed in Massachusetts. Do I owe Mass. state tax on the sale? My employer seems to have included the amount in my Mass W-2 instead of my N.H. one. - Steve, Manchester, N.H.

The following answer was provided by Nick Puniello, CPA, Puniello & Company, PC.

A: You recognize income from the exercise and sale of incentive stock options on the date of sale. Since you were employed in Massachusetts on the date the options were exercised and sold, you must pay tax in Massachusetts on the sale.