NJ's "convenience of the employer" rule does not apply to residents of Florida. See this:
https://www.nj.gov/treasury/taxation/conveniencerule.shtml
You must file a part-year resident NJ return only. The income your husband earned remotely AFTER becoming a Florida resident is not taxable by NJ.
All the income earned while he was still an NJ resident is of course fully taxable by NJ.
NJ would only tax the wages/salary of a FL resident if it were earned from work actually (physically) carried out within New Jersey.
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
