Part-year resident, in plain terms
New Jersey and New York each treat you as a resident for the stretch of the year you lived there, and as a nonresident for the rest. While you were a resident, they tax your income from every source. While you were a nonresident, they tax only income that came from inside their borders, such as wages for work done there or rent from property there.
That is why you may owe tax to both states on the same year, and why your pay stubs may not line up with where you actually lived. Withholding follows the employer's payroll setup, not your address.
The returns you may file
Moving from New Jersey to New York City usually means a New Jersey part-year resident return and a New York part-year resident return. The New York side adds a city piece for the months you were a city resident. New York has a separate form for a change of city resident status, which splits your income between the time you did and did not live in the city.
Moving the other way around the same idea applies in reverse. You still file the federal return as usual, and the federal return does not care which state you lived in.
How the dates are counted
Write down the exact day you moved, using a lease start date, closing date or the day you began living in the new place. Keep proof such as a lease, utility start date or a change of address confirmation.
Some calculations use whole months, and the rule for counting a partial month is set in the instructions for each form. A move in the middle of a month can land on either side, so read the current instructions rather than guessing.
Splitting your income
Wages are normally split by when you earned them, or by where you worked if you were a nonresident of that state. Interest, dividends and other income that is not tied to a place usually follow the days you lived in each state. A bonus paid after the move for work done before it can raise questions, so keep the pay dates.
If you had a W-2 from two employers, look at boxes 15 through 20 on each one. They show which state and city tax was withheld and on how much pay.
Credits can be split too
Some credits are prorated for a part-year resident, and some depend on the income earned while you were a resident. Whether a credit is claimed in full, in part or not at all comes from the form instructions for that year. Do not assume that a credit you got last year works the same way after a move.
Software can ask when you moved and apply those rules for you, and MCC Tax 1040 does this for its supported years. Check any result against the official instructions before you file.
What to gather before you start
Collect every W-2 and 1099, your move date and proof, and the state and city withholding on each form. If you kept pay stubs, they help match where each paycheck was taxed. A short timeline of where you lived and worked, written once, makes every form easier.
Common questions
Do I file two state returns if I moved once?
Often yes, one for each state you lived in or earned income in, as a part-year resident for each. The details depend on your income sources, so check each state's instructions.
Does the federal return change when I move?
No. The federal return covers the whole year in one return. Only the state and city returns are split.
Can my employer fix the wrong state withholding?
Sometimes, but the return is where the final tax is settled. Withholding in the wrong state is usually sorted out when you file.
This guide is general information, not tax, legal or accounting advice. Rules, fees and due dates change; check with the IRS, the NJ Division of Taxation or a licensed professional for your situation.