For federal tax purposes, the IRS looks to state or foreign law to determine whether individuals are married. The IRS has a general rule recognizing a marriage of same-sex spouses that was validly entered into in a domestic or foreign jurisdiction whose laws authorize the marriage of two individuals of the same sex even if the married couple resides in a domestic or foreign jurisdiction that does not recognize the validity of same-sex marriages.
For more information, please click on the links provided below.
Article on Same-Sex Marriages Recognized for Federal Tax
Frequently Asked Questions for Individuals of the Same Sex Who Are Married Under State Law