you need to file a NJ non-resident return reporting only the rental property located there
Who Must File a New Jersey Income Tax Return
You must file a return if – and your gross income from
everywhere for the entire year was
your filing status is: more than the filing threshold:
Single or
Married/CU partner, filing separate return $10,000
Married/CU couple, filing joint return
Head of household
Qualifying widow(er)/surviving CU partner $20,000
It depends.
New Jersey requires you to file a return as a nonresident if you earned over $10,000 (single or Married Filing Separately) or $20,000 (Married Filing Jointly, Head of Household, or Qualifying widow) from all sources, not just based from New Jersey sources.
If you meet those requirements, you will need to file a nonresident New Jersey return (Form NJ-1040NR). Be sure to mark the property as being located in NJ in the federal interview section.
Prepare the nonresident New Jersey return before preparing your state resident return.
Make sure you only reflect the New Jersey source income in the interview section. This will ensure you are only taxed on that income.