A Married Couple Need Not Live Together to File a Joint
A married couple need not live together to file a joint return.
A legally married same-sex couple can file a joint return.
A widow or widower may file a joint tax return and claim an exemption for the deceased spouse in the year of the spouse's death as long as the surviving spouse does not remarry before the end of the year.
An unmarried taxpayer may file as head of household if he maintains a home for his qualifying child.