Hey there!
You'd file in both states: a resident return for New Jersey plus a nonresident return for New York.
New York collects taxes on income you earned while working there. And New Jersey requires that you report all of your income (including that earned in New York), but will credit the New York taxes so you don't get double-taxed.
Make sure you prepare your New York return first, so we can properly credit the taxes on your New Jersey return.
I hope this helps!
