You must file an amended New Jersey tax return if:
An amended return must be filled out completely, even if you are only amending one line. You cannot change your filing status after the filing deadline has passed, unless you have changed your filing status for federal purposes.
Which Form to Use
Residents. File Form NJ-1040X for the appropriate year. You must file a paper Form NJ-1040X, whether your original return was filed electronically or on paper. Include an explanation of the changes in the space provided on page three of the return.
Nonresidents. File Form NJ-1040NR for the appropriate year, and write the word "Amended" in bold letters in the upper right hand corner of the return. There is no special form for amending nonresident returns.
When to File
You can amend your return at any time, but to claim a refund, the amended return must be filed within three years from the original due date of the return or two years from the time the tax was paid, whichever is later.
If the IRS changes the amount of your federal earned income credit, which changes your New Jersey Earned Income Tax Credit, you must file an amended New Jersey return within 90 days of the date of the notification.
When Not to Amend
Amending your return means filing a new tax form. You cannot file an amended return until after your original return has been received and processed. You can check the status of your return. If you need more information, contact the Customer Service Center at 609-292-6400.
Do not amend if you have not actually mailed or electronically filed your return yet. Just open your return and make any changes, then file it.
Do not amend if your return is still pending. You must wait until the return is processed before amending.
You also should not amend if you received a notice from us that does not specifically tell you to amend (e.g. we changed your math error corrections, request for additional forms, etc.). Just follow the instructions in the notification.