Following a case in the US federal court, the IRS has issued a revenue ruling which states that for federal tax purposes, the terms “spouse”, “husband ans wife”, “husband” and “wife” include individuals married to another person of the same sex if they are lawfully married under state law. Similarly, the term “marriage” includes marriage between individuals of the same sex. It also ruled that individuals of the same sex who were legally married in a state where this is legal, are still considered married for federal tax purposes even if they are currently domiciled in a state where such marriages are not recognised. Civil unions, registered partnerships which are not demominated as marriage are not recognised for IRS purposes.
As a result of this ruling, anyone legally married to another person of the same sex must file as married, either filing jointly or separately in 2013. It may also be possible to file amended returns for previous years to reflect their married status.
Note that an individual married to a non-resident alien can no longer file as single but must now file as married filing separately (unless the “head of household” option is available).