The IRS has announced that validly married same-sex couples will be treated as married regardless of where they live.
While this is good news for the many married couples who live in states that refuse to recognize their marriages, the IRS has also declared that it will not treat civil unions, registered domestic partnerships, and other similar formal relationships as the equivalent of marriages. For New Hampshire couples in a valid civil union/domestic partnership from another state, their status with the IRS is less clear, and such couples should speak with an attorney to better understand whether their civil union/domestic partnership will be recognized as a marriage for federal tax purposes.
And a little bit more bad news–the costs of stepparent and second parent adoptions will no longer be tax deductible for married same-sex couples. IRS FAQs
Don’t forget to get your retroactive tax refund–the IRS is permitting amended tax returns to be filed for past years in accordance with their rules.