Common-Law Marriage and Taxes: Can You Still File Single?

The short answer: probably not. If you have a valid common-law marriage under the law of a state that recognizes it, the IRS treats you as married for federal income tax. That means your filing status choices are generally married filing jointly or married filing separately — not single. "Single" is a status reserved for people who are legally unmarried, and a valid common-law marriage is a legal marriage.

The catch is the word valid. A common-law marriage only exists if your situation meets a recognizing state's specific requirements. Many people who think they are "common-law married" simply are not — and those people genuinely can file single. So the real question is not "can I file single?" but "am I actually married under my state's law?" This article walks through both halves.

Why your filing status follows your state

Federal tax law does not create marriage. It borrows the answer from state law. If a state where the marriage was entered into would treat you as married, the federal government treats you as married too. Congress made this explicit in the Respect for Marriage Act, which provides that "for the purposes of any Federal law, rule, or regulation in which marital status is a factor, an individual shall be considered married if that individual's marriage… is valid in the State where the marriage was entered into" (1 U.S.C. § 7).

Income tax is a federal law "in which marital status is a factor." So the chain is simple: if your state recognizes your common-law marriage as valid, you are married for federal tax purposes, and a married person cannot correctly file as single.

The same rule protects same-sex couples. Under Obergefell v. Hodges, 576 U.S. 644 (2015), and the Respect for Marriage Act, a valid marriage — including a valid same-sex common-law marriage formed in a recognizing state — must be recognized by the federal government and by other states.

Common-law marriage is rare — and that matters

Only a small minority of states still allow a new common-law marriage to be formed, and a few others recognize ones created before a cutoff date. Family law is overwhelmingly state law, so there is no nationwide rule and no "all states" answer here. Living together for a certain number of years does not, by itself, create a common-law marriage anywhere — that is the single most common myth.

In the states that do recognize it, you typically must show all of the following at the same time:

• Capacity and intent. Both of you are legally free to marry and presently agree to be married to each other — not engaged, not "someday," but married now.
• Living together as a couple.
• Holding yourselves out to others as married — using "husband," "wife," or "spouse," sharing a last name, filing joint applications, introducing each other as married.

If you don't meet your state's test, you are not married, and you file single (or head of household if you qualify). To work through whether you actually meet the elements, see our companion guide on whether you are common-law married.

If you ARE common-law married: your real options

A valid common-law marriage is a full marriage. You don't get a "single" option just because there was no ceremony or certificate. Your choices are:

• Married filing jointly (MFJ). One return for both spouses; usually the lowest combined tax, but both of you are jointly responsible for the full amount owed.
• Married filing separately (MFS). Each spouse files a separate return. This often costs more in total tax and limits some credits, but it keeps your tax liability separate from your spouse's.
• Head of household (HoH) — only if you qualify as "considered unmarried." Even while still married, you may use HoH if you lived apart from your spouse for the entire last six months of the year, paid more than half the cost of keeping up your home, and have a qualifying child living with you for more than half the year whom you can claim as a dependent. HoH is more favorable than MFS, but it is still not "single."

Notice that "single" is not on this list. If you are validly married on the last day of the year, single is simply not an available status.

Watch the calendar: your status is set on December 31

For federal income tax, your marital status for the whole tax year is generally determined by your status on the last day of that year (December 31). If your common-law marriage existed on that date, you are treated as married for the entire year. This is time-sensitive: a marriage that formed mid-year still makes you "married" for that year's return.

Moving to a state that doesn't recognize common-law marriage

A frequent surprise: if you formed a valid common-law marriage in a recognizing state and then moved to a state that does not allow new ones, you are generally still married. States typically honor a marriage that was valid where it was created, and the Respect for Marriage Act reinforces that out-of-state marriages must be respected (28 U.S.C. § 1738C). So moving across a state line does not quietly turn you back into a single person for tax purposes. To actually end a common-law marriage, you generally need a divorce, just like any other marriage.

Why filing single when you're married is risky

If you are validly married and file single, your return is incorrect. The IRS can reassess your tax, and you may owe additional tax, interest, and penalties. There is also a consistency problem: you cannot claim to be married when it helps (for example, for inheritance, insurance, immigration, or a partner's Social Security or benefits) and single when that helps on taxes. Treating the relationship as a marriage in one arena is exactly the kind of "holding out" that helps prove a common-law marriage exists in the first place.

What you can do

1. Pin down your state. Confirm whether the state where you believe the marriage formed even recognizes common-law marriage. Most don't.
2. Test the elements honestly. Did you both presently agree to be married, live together, and hold yourselves out as married? If any piece is missing, you are likely not married — and you can file single. Use the am-I-common-law checklist.
3. If you are married, choose MFJ or MFS — not single. Compare the two; MFJ is usually cheaper, MFS shields you from a spouse's tax issues.
4. If you're separated, check head of household. If you've lived apart since at least July 1, pay over half your home's costs, and have a qualifying child, HoH may be available even though you're still married.
5. Be consistent everywhere. Make sure how you file taxes matches how you describe your status on other legal and financial paperwork.
6. Fix past returns if needed. If you filed single in a year you were actually married, you can generally amend. You typically have three years from when you filed (or two years from when you paid the tax, if later) to file an amended return and claim a refund.
7. Get tailored help for close calls. Whether a common-law marriage exists is a fact-specific legal question with big tax consequences. A tax professional or family-law attorney in your state can confirm your status before you file.

Bottom line

You can file single only if you are genuinely unmarried. If your state recognizes your common-law marriage, federal law treats you as married, and you must file jointly or separately — or as head of household if you meet the strict "considered unmarried" test. If you don't actually meet your state's common-law marriage requirements, you were never married, and single is the right box. The whole answer turns on that one threshold question.

This article is general information, not legal or tax advice; consult a qualified attorney or tax professional about your specific situation.