Marital status is determined based on where a marriage is celebrated, not where a couple resides. Two persons are married for federal tax purposes if they were lawfully married in a state whose laws authorize the marriage. In other words, if a marriage was legal in the state where the marriage was celebrated, then the couple is considered married for federal tax purposes.
That might sound complicated, but the Supreme Court made the whole issue significantly easier with its groundbreaking decision in Obergefell v. Hodges in 2015.
Obergefell v. Hodges—All States Are Now Equal
On Oct. 6, 2014, the U.S. Supreme Court let stand decisions in the 4th, 7th, and 10th Circuit Courts of Appeals that overturned state-level bans on same-sex marriage. Specifically, Indiana, Oklahoma, Utah, Virginia, Wisconsin, Kansas, North Carolina, South Carolina, West Virginia, and Wyoming became required to recognize same-sex marriages within their states.
Then the U.S. Supreme Court handed down a second decision in Obergefell v. Hodges less than a year later, on June 26, 2015. This decision actually legalized same-sex marriages at the federal level. In a 5-4 opinion, the Court also mandated that all states must license and recognize same-sex marriages.
The ramifications of this decision trickled down to state tax returns. All legally married couples must now file married returns, either jointly or separately, at both the state and federal level. At least 13 states had resisted accepting married returns from same-sex couples prior to Obergefell v. Hodges, but they were now obligated to do so and that remains the case in 2019.
This doesn't mean there aren't still some rules you should keep in mind.
Marital Status and Filing Options
The rule is that if you're legally married on the last day of the year—Dec. 31—you're married for the entire year for tax purposes. Married couples must choose between married filing jointly and married filing separately filing statuses in most cases.
Some might qualify for head of household status if they didn't live together at any time during the last six months of the tax year and have no intention of ever cohabiting again, but this filing status comes with a host of other qualify rules as well.
Registered Domestic Partnerships and Civil Unions
Domestic partners and civil union couples are not married for federal tax purposes. In Revenue Ruling 2013-17, the IRS writes:
"For federal tax purposes, the term 'marriage' does not include registered domestic partnerships, civil unions, or other similar formal relationships recognized under state law that is not denominated as a marriage under that state’s law."
Domestic partners and civil union couples must therefore choose between the single or head of household filing statuses.
Domestic partners and civil union couples might be required to file married tax returns at their state level, however. California, Nevada, and Washington apply community property laws to domestic partners in the same way these laws apply to married couples. Domestic partners might have to allocate their income and deductions using community property methods when preparing their federal tax returns. See Publication 555, Community Property, on the IRS website for details.
NOTE: Tax laws change periodically and the above information may not reflect the most recent changes. Please consult with a tax professional for the most up-to-date advice. The information contained in this article is not intended as tax advice and it is not a substitute for tax advice.