If you file your federal return as MFJ, NJ requires that you also file your NJ return MFJ, unless: 1) one spouse was a nonresident and the other was a resident during the entire tax year, and both had income from NJ sources; or 2) both spouses were nonresidents for the entire tax year, and only one had income from New Jersey sources.
https://www.state.nj.us/treasury/taxation/pdf/current/1040i.pdf
https://www.state.nj.us/treasury/taxation/pdf/current/1040nri.pdf
See this for an explanation of how NJ taxes part-year residents:
https://www.state.nj.us/treasury/taxation/pdf/current/1040nri.pdf
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
