If you are under the New Jersey filing threshold, Lines 30 through 49 of your New Jersey Form NJ-1040 should not be completed.
New Jersey instructions for Form NJ-1040 State of New Jersey Income Tax-Resident Return, on page 21:
Line 29 - New Jersey Gross Income
Subtract Line 28c from Line 27 and enter the result on Line 29. If less than zero, make no entry.
Not Required to File a Return
You are not required to file a return if your income is at or below the filing threshold. However, you still need to file if you:
Do not complete Lines 30 through 50. Continue completing the return with Line 51.
Note that any link in the information above is updated each year automatically and will take you to the most recent version of the document at the time it is accessed.