The ruling by the Treasury and the Internal Revenue Service (IRS) applies regardless of whether the couple lives in a jurisdiction that recognises same-sex marriage or a jurisdiction that does not recognise same-sex marriage, the Treasury said yesterday.
"Today's ruling provides certainty and clear, coherent tax filing guidance for all legally married same-sex couples nationwide.
It provides access to benefits, responsibilities and protections under federal tax law that all Americans deserve," said the Treasury Secretary Jacob J Lew.
Under the ruling, same sex couples will be treated as married for all federal tax purposes, including income and gift and estate taxes.
The ruling applies to all federal tax provisions where marriage is a factor, including filing status, claiming personal and dependency exemptions, taking the standard deduction, employee benefits, contributing to an IRA, and claiming the earned income tax credit or child tax credit.
However, the ruling does not apply to registered domestic partnerships, civil unions, or similar formal relationships recognised under state law.
Thirteen of the 50 US states have legalised same-sex marriage while about 30 states have decreed that marriage can only exist between a man and a woman.
The District of Columbia, or Washington, the US capital, also authorises it.
