Q. Can they use CT address on federal return?
A. Yes. You can use either residence as the address for the joint federal return.
I cannot answer specifically, for your situation. Most states allow you to file a joint (MFJ) state return even when only one spouse lives there and/or works there. It's just a matter of allocating the income, to the proper state. Some states (e.g. Ohio) even mandate that you file the state return as MFJ if you used MFJ on the federal return.
