I recall, when this all started, you mentioned your desire to amend *two* state returns for consecutive tax years. I suggest verifying, if possible, which filed state return is being acknowledged, the one you successfully e-filed or the one reported as failed. The data returned from you should list the tax year, and minimal identification information, such as your truncated TIN (e.g., ***-**-1234) and maybe your name and address. If the failed e-filing is *not* the one acknowledged, it stands to reason you will definitely need to mail that one in. You might review the TurboTax Filing Instructions, which should comprise the first page or two of your amended return to make sure the location to mail your return isn't printed there. Otherwise, the revenue or taxation agency for your state almost certainly has a website that provides provide support or telephone/mailing address contact information by which you may learn where you need to mail the amended return. Even a Google search, "Where to mail amended MA tax return" ought to give you the answer.
