New Jersey Statutes Title 54A. New Jersey Gross Income Tax Act 54A § 5-6

(a) Separate return. If the income of husband or wife who are both nonresidents of this State and are subject to tax under this act is determined on a separately filed return, their incomes from sources within this State shall be separately determined.

(b) One spouse a nonresident. If either husband or wife is a nonresident and the other a resident, separate taxes shall be determined on their separate incomes on such forms as the director shall prescribe, unless both elect to determine their joint income as if both were residents in which event their tax liabilities shall be joint and several.

(c) The filing requirements for nonresidents shall be governed by the provisions of section 54A:8-3.1 except with respect to the conditions set forth in subsection (b) of this section.