Can I file a Married Filing Separate Connecticut return if I filed as Married Filing Joint on my federal return?

Generally, your filing status must match the filing status on your federal return. However, according to the Connecticut instructions , there are certain circumstances in which you are allowed to file a MFS state return when you have filed a MFJ on the Federal return. If you do change the status you will not be able to electronically file this return: 

1. When one spouse is a Connecticut resident or a nonresident and the other spouse is a part-year resident, each spouse who is required to file a Connecticut income tax return must file as
   married filing separately.
2. When one spouse is a Connecticut resident and the other is a nonresident, each spouse who is required to file a Connecticut income tax return must file as married filing separately unless
   they:
   •  File jointly for federal income tax purposes; and
   •  Elect to be treated as if both were Connecticut residents for
     the entire taxable year.
3. When both spouses are part-year residents of Connecticut but do not have the same period of residency, married filing separately is their Connecticut income tax filing status.
4. When both spouses are part-year residents of Connecticut and have the same period of residency, they may choose married filing jointly or married filing separately as their Connecticut income tax filing status.
5. When both spouses are nonresidents of Connecticut and only one has income derived from or connected with sources within Connecticut, only that spouse is required to file a Connecticut income tax return and that spouse’s Connecticut income tax filing status is married filing separately for Connecticut unless they both elect to file a joint Connecticut income tax return. If an election is made, married filing jointly is their Connecticut income tax filing status.
6. When one spouse is a nonresident alien and the other is a citizen or resident of the United States, each spouse who is required to file a Connecticut income tax return must file as married filing separately unless:
   • An election is made by the nonresident alien and his or her spouse to file a joint federal income tax return;
   • A married filing joint return is filed for federal income tax purposes; and
   • The spouses are otherwise required or permitted to file a joint Connecticut income tax return.