Just to make sure we're on the same page, are you asking about the subscriber number on Form MA 1099-HC on your Massachusetts state return?
Form 1099-HC is issued by your health insurance carrier. To download an electronic version of your 1099-HC, you can sign into your medical insurance carrier’s online account, or you can contact member services at the number on your ID card.
For more information, see Mass.gov's 1095-B and 1099-HC tax form page.
