(1) If the federal tax liability of husband or wife is determined on separate federal returns, their tax liabilities in this state shall be separately determined.

(2) Except as provided in subsection (3) of this section, if the federal tax liability of husband and wife is determined on a joint federal return, their tax liability shall be determined in this state jointly and their tax liability shall be joint and several.

(3) If the federal tax liability of husband and wife is determined on a joint federal return and either husband or wife is a nonresident individual or partial-year resident individual and the other a resident individual, separate taxes shall be determined on their separate tax liabilities in this state on such forms as the Tax Commissioner shall prescribe and their tax liability shall be separate unless both elect to determine their joint tax liability in this state as if both were resident individuals, in which case their tax liability shall be joint and several. If a husband and wife file a joint federal income tax return but determine their tax liabilities in this state separately, they shall compute their tax liabilities in this state as if their federal tax liabilities had been determined separately.

(4) During the time a claim for credit or refund may be filed pursuant to section 77-2793, a husband and wife electing to be taxed as if both were residents of this state may revoke the election by each filing a separate return on such forms and in such manner as may be required by the Tax Commissioner.