This guide is general legal information, not legal advice, and does not create an attorney–client relationship. Rules change and vary by state — verify current requirements with official sources or a licensed attorney.
A couple buys a house together, pools income for a decade, raises children, and splits up. If they were married, an entire body of state law would tell a court how to divide what they built. Because they were not, in most states almost none of that law applies. There is no marital estate, no spousal support, no automatic inheritance, and no family court process designed for the situation.
That gap is what a cohabitation agreement fills. It is a contract between unmarried partners covering property, contributions, support, and what happens if the relationship ends or one partner dies. Whether and how such a contract is enforced is decided under each state's law — contract law, property law, and each state's public-policy limits — so the same document can be treated differently across state lines.
Key takeaways
- Living together, however long, does not create marriage-like rights in the large majority of states. Duration alone changes nothing.
- A small minority of states still permit common-law marriage to form, and several others recognise ones validly formed elsewhere or before a statutory cutoff.
- Courts in many states enforce express contracts between cohabitants, but the willingness to imply agreements from conduct varies enormously.
- Cohabitation agreements are not governed by a widely adopted uniform act the way premarital agreements are, so they rise or fall on ordinary contract principles.
- Children's rights are unaffected by their parents' marital status — support and custody follow parentage, not marriage.
The default rule: living together creates almost nothing
Marriage triggers a package of default rules automatically. Property acquired during the marriage becomes marital or community property. A spouse can seek support. A surviving spouse takes a share of an estate even if the will says otherwise, and can serve as next of kin for medical decisions. Employer benefit plans and pension rules build in spousal protections. The Legal Information Institute's summaries of divorce and property division describe those defaults, and our guide to community property and equitable distribution covers them in more depth.
Unmarried partners receive essentially none of it by default. Property belongs to whoever holds title. Neither partner owes the other support. Neither inherits without a will. Neither is automatically next of kin. A partner who left the workforce to raise children or support the other's career has, in most states, no claim rooted in the relationship itself — so the person who contributed less on paper, and often more in reality, carries the risk. That asymmetry is the reason to put something in writing while the relationship is good.
Three exceptions worth knowing
Common-law marriage
A handful of states still allow a marriage to form without a licence or ceremony where the couple agrees to be married, lives together, and holds themselves out publicly as married. Texas, Colorado, and Utah are among the commonly cited examples; each has its own requirements, and Texas provides a registration form as one route to proof. Several other states abolished common-law marriage prospectively but continue to recognise unions formed before the cutoff date.
Two things about it are widely misunderstood. There is no "seven-year rule" — no state creates a marriage by the passage of time. And because every state must recognise a marriage validly formed elsewhere, a couple who met the requirements while living in a common-law state remain married after moving to a state that does not permit new common-law marriages. Ending one requires a divorce, exactly as with any other marriage.
Contract claims between partners
Since the California Supreme Court's decision in Marvin v. Marvin (1976), many states have been willing to enforce express contracts between unmarried partners about property and support, provided the agreement is not founded on sexual services as consideration. Some states go further and will imply an agreement from the parties' conduct; others require a writing; and a minority decline to enforce cohabitation-related contracts at all on public-policy grounds. The popular term "palimony" describes support claims of this kind, but it is journalism rather than a legal category, and no state provides it as an automatic entitlement.
Equitable doctrines
Where no contract exists, partners sometimes recover through general equitable theories — unjust enrichment, resulting or constructive trust, quantum meruit — by showing they contributed money or labour to property titled in the other's name. Washington's courts developed a distinctive approach, applying a "committed intimate relationship" analysis that distributes property acquired during a marriage-like relationship. That doctrine is a state-specific development, not a national rule, and most states offer nothing comparable.
State variation: The same twelve-year relationship, ending with the same facts, can produce a substantial property award in one state and nothing at all in another. This is one of the widest state-to-state gaps in family law, and it is exactly the uncertainty a written agreement removes.
Registered partnerships after 2015
Domestic partnership and civil union registries were built largely as substitutes for marriage before nationwide marriage equality. After 2015 the landscape fragmented. Several states converted existing civil unions into marriages or closed their registries. Others kept them open, and California expanded eligibility to all adult couples in 2020, so a registry is no longer limited to same-sex or senior couples there. A number of cities and counties maintain local registries whose main effect is access to municipal employee benefits.
Where a registry exists, registration usually confers state-level rights resembling those of spouses — hospital visitation, some inheritance rights, sometimes support obligations on dissolution — but generally not federal ones. Federal tax filing status, Social Security spousal benefits, and immigration status typically follow marriage, not registration.
What a cohabitation agreement should cover
- Property brought in. A schedule of what each person owned at the start and a statement that it stays separate.
- The shared home. Who holds title, how the down payment and mortgage payments are credited, what happens on separation — buyout formula, sale, or right of first refusal — and how improvements are treated.
- Contributions, expenses, and debt. Whether one partner's payment of household expenses creates an ownership interest, how unequal contributions are accounted for, and who is responsible for which debts.
- Support on separation. Whether either partner will pay the other, for how long, and on what trigger — particularly important where one partner leaves paid work.
- Jointly acquired property. How vehicles, furniture, investments, and pets are divided.
- Death. Commitments to maintain a will, a beneficiary designation, or life insurance, and what happens to the home if one partner dies.
- Process terms. Choice of law, a mediation clause, severability, and a plain statement that each party had the opportunity to consult independent counsel.
Execution practices borrowed from marital agreements make these documents far more durable: full written financial disclosure attached as an exhibit, separate lawyers, no signing under time pressure, and notarisation. The enforceability logic parallels the one set out in our guide to prenuptial and postnuptial agreements, even though the Uniform Law Commission acts that govern premarital and marital agreements do not extend to unmarried couples in most enactments.
The documents an agreement cannot replace
A cohabitation agreement binds the two partners. It does not bind hospitals, employers, plan administrators, banks, or probate courts. Four gaps have to be closed separately:
- Estate documents. An unmarried partner inherits nothing under intestacy law in any state. A will or trust is the only way to transfer assets, and our comparison of wills and living trusts covers the choice between them.
- Beneficiary designations. Retirement accounts and life insurance pass by designation, not by will or contract. Federal law governing employer plans, administered through the Employee Benefits Security Administration, generally directs plans to pay according to their own documents and the designation on file — so a promise in a contract does not redirect a plan payout.
- Health care and financial authority. A durable power of attorney and a health care directive naming the partner are what create decision-making authority; the relationship itself does not.
- Titling. How a deed is held — sole name, tenants in common, joint tenants with right of survivorship — often determines the outcome regardless of what the agreement says. Align the deed with the agreement.
Children are on a separate track
None of the above applies to children. Legal parentage, not marital status, determines support and custody, and both are decided under the same standards used for married parents — state guidelines for support and the best-interests standard for parenting decisions. State child support agencies operating under the federal programme described by the Office of Child Support Services serve unmarried parents on the same terms as divorced ones.
What unmarried parents do need is a clear parentage record, because the marital presumption is unavailable to them. That means signing an acknowledgment of paternity or obtaining a court order — with the deadlines and consequences set out in our guide to establishing and challenging paternity. No cohabitation agreement can waive a child's right to support or predetermine custody; those terms are void everywhere.
Frequently asked questions
If we live together for seven years, are we common-law married?
No. The seven-year figure is folklore. In the small minority of states that still permit common-law marriage, the requirements are a present agreement to be married, cohabitation, and holding yourselves out publicly as spouses — with no minimum duration. In every other state, no amount of time creates a marriage.
Can a cohabitation agreement include a support obligation?
In most states, yes, provided it is an express written promise supported by lawful consideration and not conditioned on sexual services. Enforcement is by ordinary contract suit rather than family court, which affects speed and remedies. A few states remain hostile to such terms, so drafting should account for where enforcement would occur.
Do we need an agreement if everything is titled jointly?
Joint titling solves ownership but not much else: it does not address unequal contributions, what happens if one partner stops paying, who buys the other out, or support. It also does not govern the many assets held individually. Titling and a written agreement do different jobs, and most couples need both.
Where to go from here
Two conversations are worth having before the question becomes urgent. The first is factual: whose name is on the deed, the accounts, the policies, and the beneficiary forms, and does that match what you both believe the arrangement to be. The second is contingent: if this ended tomorrow, by separation or by death, what would each of you walk away with under your state's law rather than under your assumptions.
Where the answers diverge, a cohabitation agreement plus a short set of estate documents closes the gap for far less than litigation costs later — and for couples who may marry eventually, a well-drafted cohabitation contract often becomes the first draft of a marital one. The family and divorce law hub covers the surrounding issues. This article is general legal information, not advice; the enforceability of cohabitation agreements, the availability of common-law marriage, and registry rules are all matters of state law that vary considerably.
