J.K. Lasser's Your Income Tax 2013: For Preparing Your 2012 Tax Return

1.4 Filing a Joint Return

If you are married at the end of the year, you may file a joint return with your spouse. For federal tax purposes, a marriage means only a legal union between a man and woman as husband and wife. Filing jointly saves taxes for many married couples, but if you and your spouse both earn taxable income, in some cases overall tax liability is reduced by filing separately (1.3).

You may not file a 2012 joint return if you were divorced under a decree of divorce or separate maintenance that is final by the end of the year. You may file jointly if you separated during 2012 under an interlocutory (temporary or provisional) decree or order, so long as a final divorce decree was not entered by the end of the year. If during the period that a divorce decree is interlocutory you are permitted to remarry in another state, the IRS recognizes the new marriage and allows a joint return to be filed with the new spouse. However, courts have refused to allow a joint return where a new marriage took place in Mexico during the interlocutory period in violation of California law.

Both spouses generally liable on joint return but “innocent” spouse may be relieved of liability.

When you and your spouse file jointly, each of you may generally be held individually liable for the entire tax due, plus interest and any penalties. The IRS may try to collect the entire amount due from you even if your spouse earned all of the income reported on the joint return, or even if you have ...