B. If the federal income tax liability of either spouse is determined on a separate federal return their income tax liabilities under this Part shall be are determined on separate returns.;

C. Except as provided in subsection 2, if the federal income tax liabilities of husband and wife spouses are determined on a joint federal return, they shall file a joint return under this Part and their tax liabilities shall be are joint and several.; and

D. If neither spouse is required to file a federal income tax return and either or both are required to file an income tax return under this Part, they may elect to file separate or joint returns and pursuant to such election their liabilities shall be are separate or joint and several.

2. Nonresidents. If both husband and wife spouses are nonresidents and one has no Maine-source income, the spouse having Maine-source income shall file a separate Maine nonresident income tax return, as a single individual, in which event his that spouse's tax liability shall be is separate; but they may elect to determine their joint taxable income as nonresidents, in which case their liabilities shall be are joint and several.

If either husband or wife spouse is a resident and the other is a nonresident, they shall file separate Maine income tax returns as single individuals, in which event their tax liabilities shall be are separate; but they may elect to determine their joint taxable income as if both were residents and, in that case, their liabilities shall be are joint and several.

Sec. 12. 36 MRSA §5228, sub-§6, as repealed and replaced by PL 1985, c. 691, §§35 and 48, is amended to read:

6. Joint estimated tax payment. If they are eligible to do so for federal tax purposes, a husband and wife spouses may jointly estimate tax as if they were one taxpayer, in which case the liability with respect to the estimated tax shall be is joint and several. If joint estimate payment is made, but husband and wife spouses elect to determine their taxes under this chapter separately, the estimated tax for the year may be treated as the estimated tax of either husband or wife spouse, or may be divided between them, as they may elect.