Only a small number of U.S. states and the District of Columbia currently recognize new common law marriages, while many others recognize only those that were validly established before the practice was abolished or those formed in another state.
CDC data from the National Survey of Family Growth shows that among first premarital cohabitations, the largest proportion (40%) transitioned to marriage within three years, while 32% remained intact without marrying and 27% dissolved.
Whether a couple qualifies depends on the laws of the state, and simply living together for many years does not automatically create a common-law marriage.
Understanding the legal requirements and the rights that come with a valid common law marriage is essential, especially when questions arise about property division, inheritance, healthcare decisions, or divorce.
Let's learn how common law marriage works and the legal rights it may provide.
No Such Thing as a National Standard
Common law marriage, sometimes called informal marriage, is a legal status where a couple is treated as married without a license or ceremony. It's not recognized everywhere. Only a small number of states still allow couples to form one going forward, and the requirements vary sharply between the states that do.
The couple has to plan on being married, they have to actually live together, and they have to present themselves to the world as a married pair, like telling family, using the same last name, and filing joint tax returns.
But "consistent in idea" doesn't really mean "consistent in practice." Some states have age requirements. Some require a specific duration of cohabitation, though that's less common than people assume. Some allow the marriage to be formalized after the fact through a simple filing with the county clerk.
Texas: One of the Last States Where It's Still Formed
Texas is still one of those states where a common-law, or informal, marriage can be put together even today. The rules are clear. For it to count, both people have to be at least 18, neither one can already be married to somebody else, and the pair has to actually agree to be married while they are living together in Texas and also acting like spouses in public.
If those pieces are satisfied, Texas treats the connection as a full legal marriage in essentially every way, even if it didn't start with the usual ceremony. Property acquired during the relationship is community property, subject to division if the couple splits.
A surviving partner can inherit under the state's intestacy rules if the other partner dies without a will. Couples can even file a Declaration of Informal Marriage with the county clerk to put a clear, provable date on when the marriage began, which matters if a dispute ever arises about whether the marriage existed at all.
Ending an informal marriage in Texas isn't simpler than ending a formal one. It still requires a divorce, filed and litigated the same way as any other.
Simply moving out doesn't dissolve it, and Texas law creates real-time pressure around this: if a couple separates and neither party takes legal action to establish the marriage within a couple of years, the law presumes no marriage ever existed, which can strip a partner of rights they'd otherwise have.
Illinois: A State That Closed This Door Over a Century Ago
Illinois ended common-law marriage back in 1905, so it became one of the earliest jurisdictions in the nation to stop it. Under Illinois law, to have a valid marriage, you need a license plus a ceremony that's carried out by a person who is authorized to solemnize it. Living together for any length of time, no matter how the couple presents itself socially or financially, does not create a marriage under Illinois law.
There's one narrow exception. Illinois will generally recognize a common law marriage if it was validly formed in another state, in which one state will often honor a legal status that was properly created somewhere else. So if two people satisfied every requirement for an informal marriage in Texas and then later moved to Illinois, they may still be treated as married, as long as they can actually show that the marriage was valid where it started.
On the other hand, if a couple just lived together in Illinois the entire time, there's no comparable recognition, even if it lasted a bunch of years and they thoroughly braided their money and bills together.
If the relationship is not considered a marriage, in Illinois there usually is no automatic right to a split of property if things end, no automatic inheritance rights if a partner dies without a will, and no built-in authority to make health care decisions for one another.
People who want those protections, without entering a formal marriage, generally need some cohabitation agreement or similar estate planning paperwork.
A Naperville family lawyer is used to walking couples through exactly this kind of planning, since the absence of a legal marriage doesn't have to mean the absence of legal protection, provided the right documents exist before they're needed.
Why This Actually Matters Beyond the Trivia
None of this is academic. People relocate for work, for family, for a hundred reasons, and a couple who built years together, assuming certain legal protections in one state, can find those assumptions collapse entirely the moment they cross into a state like Illinois.
The opposite thing can happen as well. A couple that never really was intending to be legally married, after years of living together, might find that they somehow hit every element of what people call an informal marriage, though they never intended it at all.
That second situation usually shows up at the worst possible time. It might happen during a breakup or after someone passes away. Then suddenly one partner says "actually this was a marriage the whole time," and the other says it never was.
What This Means for Couples Living Together
Cohabitation can be a good thing in many instances. Still, non-married couples should be clear about their legal status long before the question becomes inevitable in the crisis of a relationship. In a state that still recognizes common law marriage, that could mean knowing what conduct could create one, or deciding to formalize the relationship by executing a Declaration of Informal Marriage if that is really your intent.
In a state like Illinois, where no amount of cohabitation creates a marriage, the conversation is different. Couples need to think deliberately about property titling, powers of attorney, and estate planning documents, since the law won't fill those gaps automatically the way it does for married spouses.
Either way, the core lesson holds regardless of state: assumptions about legal status are a poor substitute for actually knowing the rule where a couple lives. What counts as marriage, informally or otherwise, is one of the few areas of family law where the answer depends on which side of a state line a couple happens to call home.
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