Can an Unmarried Couple File Jointly for Income Tax?

You get some benefits when you file a joint tax return, including possibly lower tax rates and some increases in deduction limits. Unmarried couples are allowed to file joint returns in some instances, dependent on state statutes. The Internal Revenue Service recognizes most unions allowed under state law, with the exception of registered domestic partnerships. If you meet certain criteria, you and your partner may file jointly, but consider some legal issues before you do so.


Unmarried couples may file jointly if they meet certain IRS criteria, such as being in a state-recognized common-law marriage.

Requirements for Unmarried Filing Jointly

In most cases, the IRS requires couples to be legally married to file a joint tax return. However, the IRS also allows couples who aren’t legally married but are considered married by common law to also file jointly.

As of publication, only 10 U.S. states, plus the District of Columbia, recognize common law marriages. These include Colorado, Iowa, Kansas, Montana, New Hampshire, Oklahoma, Rhode Island, South Carolina, Texas and Utah. If your common-law union begins in a state that does recognize it and you later move to a state that does not, the state you move to typically must continue to recognize your marriage as valid.

Requirements for Common Law Recognition

If your union is recognized under common law, you must behave as a married couple. Each state has different requirements to meet before your marriage can be valid under common law. Some states require you and your partner to live together for a certain amount of time and act as husband and wife during that time. Other states do not place time limits on cohabitation rules.

Examples of married behavior may include calling each other husband and wife, signing legal documents together, sharing phone plans and insurance policies and generally behaving in manner that suggests to others outside your relationship that you are in fact married.

Filing Process and Requirements

Once you file a joint return with your partner, the Internal Revenue Service does not allow either party to change the filing status for that year – it remains Married Filing Jointly. All subsequent returns filed by the couple must be made under a married status, either Married Filing Jointly or Married Filing Separately. To file as single or head of household in the future, the couple must formally dissolve their union in court. Before an unmarried couple decides to file a joint return, consideration must be made to this potential future consequence.

Exceptions for Registered Domestic Partnerships

Some states recognize registered domestic partnerships for as a legal union and grant these couples the option of filing a joint income tax return. However, this option applies only to state tax returns. As of publication, the IRS doesn’t formally recognize RDP marriages.

Unmarried couples living together taxes require RDP couples to file singly for federal income tax purposes, regardless of state laws. Because joint RDP state returns are relatively new and require special attention to federal filing, consult with a tax professional prior to submitting your returns to clarify the issue.

2018 Taxes and the Marriage Penalty

Under the new tax laws, couples have an incentive to get married and file jointly. The marriage penalty that might have served as a financial deterrent in the past has practically been wiped away. Until a couple reaches $300,000 in combined income, they'll pay the same in taxes combined as they would have if they'd been single.