I want to talk about domicile. Your domicile is your one and only permanent residence. You can only have one domicile at a time. Your domicile is where you have the intention to live permanently, and doesn't have much relation to vacation homes, or other properties you might own. If your main residence is in New Jersey, that is your state of domicile.
There is no single factor that determines where your domicile is located, but some important factors include where you physically live, the location of friends and significant social relationships, the location of your doctor, dentist, attorney, and so on, the location of your church, your voter and car registration, drivers license, and your intention to return. In addition, to establish a new domicile, you must take active steps to abandon your prior domicile.
It is possible to be temporarily away from your domicile for a long time, even years, without changing your domicile.
Buying a second home in Florida does not change your domicile unless you take intentional steps to make it so, such as by moving to Florida, living there most of the time, changing your car and voter registration, getting new doctors, and so on. Even if it is your clear intention to make Florida your permanent main home, New Jersey will likely consider you a resident if you live in New Jersey more than half the year (183 or more days).
If your domicile is in New Jersey, you are New Jersey resident and report all your worldwide income and pay New Jersey tax. If you die while you are domiciled in New Jersey, your estate will be governed by the laws of New Jersey, even if you own property elsewhere.
If you are interested in estate planning, there are specialists who will help you with that.
