Assuming you are (a) an MA resident and (b) you are mailing in the actual tax form and did not e-file. If so, you sign and date on the bottom of the first page of Form 1. If you are not in situation (a) then sign and date on the bottom of the first page of Form 1-NR/PY. If you are not in situation (b) you've already signed the tax form electronically.