Hello bugjuicyturkeyleg,
Thank you for participating in this Ask the Experts event. As to your question, based on your comment it sounds like you are keeping Florida as your residence. If so, in order to have to pay NJ taxes you need to maintain a permanent home there and physically be there for 183 days or more. Because you were just visiting family and keeping your FL residence, it doesn't sound like you maintain a permanent residence in NJ even if you were there more than half the year.
Additionally, you would only need to file a nonresident return if you had NJ taxes withheld from your paycheck or had NJ sourced income. It is unclear from your post where your income is generated from--NJ or Florida or somewhere else?
Either way, you will not be double-taxed because (1) Florida doesn't have an income tax, and (2) if they did you would most likely be able to take a credit for any taxes you may have to pay to NJ if your income comes from there.
I hope that helps.
