Cohabitation Agreements in New York: What Unmarried Couples Need to Know

Start with the myth that causes the most damage: there is no common-law marriage in New York, and there hasn’t been since 1933. No number of years together, shared bank accounts, joint tax returns, or introductions as “my husband” or “my wife” creates a marriage here. Under Domestic Relations Law, a New York marriage requires a license and solemnization — a ceremony before an authorized officiant. Without that, you are legal strangers no matter how intertwined your lives are.

There is one narrow exception worth knowing. New York courts will recognize a common-law marriage that was validly formed in another state that still permits them, under ordinary conflict-of-laws principles — the Court of Appeals confirmed this in Matter of Mott v. Duncan Petroleum Corp., 51 N.Y.2d 289 (1980). But the handful of states that still allow common-law marriage have their own strict requirements, and proving one after the fact is an uphill fight. For a couple who has always lived in Western New York, the rule is simple: not married means not married.

When a marriage ends, New York’s equitable-distribution law — Domestic Relations Law §236(B) — divides the property acquired during the marriage fairly between the spouses, regardless of whose name is on it. When an unmarried relationship ends, none of that applies. The differences are stark:

• No equitable distribution. Title controls. The house, the car, the retirement account — each belongs to the person named on it, even if the other partner paid toward it for years. See our property division page for how different the rule is for married couples.
• No spousal support. Maintenance under DRL §236(B)(5-a) and (6) is available only to spouses. A partner who left a career to run the household has no support claim when an unmarried relationship ends — New York has never recognized “palimony” absent an actual contract.
• No inheritance rights. If your partner dies without a will, New York’s intestacy statute (EPTL 4-1.1) distributes everything to their legal family — children, parents, siblings. An unmarried partner inherits nothing, and unlike a spouse, has no right to claim an elective share against a will that leaves them out.
• No automatic say in a crisis. Without a health care proxy and power of attorney, an unmarried partner may have no legal voice in medical or financial decisions if the other is incapacitated.

None of this depends on fault or fairness. It is simply what the statutes say — and the only way around it is an agreement.

The controlling case is Morone v. Morone, 50 N.Y.2d 481 (1980). The Court of Appeals drew a clear line: New York courts will enforce an express agreement between unmarried partners about property and finances, applying ordinary contract law — but they will not imply an agreement from the fact that a couple lived together, shared expenses, or acted like spouses. Some states allow “implied partnership” claims between cohabitants; New York deliberately rejected that path, reasoning that the conduct of people in an intimate relationship is too ambiguous to reconstruct into a contract after the fact.

Two practical consequences follow. First, the partner who contributed without an agreement is largely out of luck — courts occasionally entertain narrow equitable claims (a constructive trust, for example, where property was conveyed in reliance on a promise), but those cases are difficult, expensive, and unpredictable. Second, and more usefully: if you put your understanding in writing, New York will hold you both to it. The same legal system that offers unmarried couples almost nothing by default gives them nearly complete freedom of contract. One caution from the case law: the agreement must rest on ordinary consideration — mutual promises about property, services, and finances — not on the intimate relationship itself.

A cohabitation agreement is flexible — it can be as narrow as one house or as comprehensive as a prenup. The issues we most often address for Buffalo and Williamsville couples include:

• The home. Who owns it, in what shares, who pays the mortgage, taxes, and repairs — and what happens on separation: buyout rights, a forced-sale timeline, how appreciation is split, and credit for down payments or renovations.
• Separate vs. shared property. What each partner brought in stays separate; what counts as jointly acquired and how it is divided.
• Bank accounts and expenses. Whether accounts are pooled or parallel, how household costs are shared, and whether unequal contributions create any reimbursement right.
• Debt. Whose student loans, credit cards, and car loans are whose — and a commitment that neither partner is responsible for the other’s debt.
• Support on separation. Whether either partner will pay anything to the other if the relationship ends. The default is zero; an agreement can create a defined, limited obligation if that is what you both want.
• Pets. Who keeps the dog is a real dispute — and unlike in a divorce, where courts now apply a “best interest of the companion animal” standard, an unmarried couple’s pet is just property. An agreement can decide it in one sentence.
• The exit process itself. Notice periods, who moves out, and a commitment to mediate disputes before anyone sues.

A good agreement is paired with the estate-planning documents the law will not supply: wills, health care proxies, powers of attorney, and beneficiary designations on life insurance and retirement accounts — because a cohabitation agreement governs a breakup, not a death.

The hard limit is children. No private contract can bind a New York court on custody or parenting time — those are always decided by the court based on the child’s best interests at the time of the dispute. The same is true of child support: the Child Support Standards Act (Family Court Act §413) applies to every parent, married or not, and parents cannot contract away a child’s right to support. For unmarried fathers, the more urgent issue is usually establishing paternity in the first place — without an acknowledgment of parentage or a court order, a father has no enforceable custody rights and the child has no support order.

An agreement also cannot make you married. It creates contract rights between two people; it does not create a marital status the outside world — Social Security, immigration law, a hospital in another state — must respect.

The most common flashpoint we see in Erie County is the jointly deeded house. When an unmarried couple takes title together and later separates, neither can force the other to sell by agreement — so the remedy is a partition action under Article 9 of the Real Property Actions and Proceedings Law. Partition is a full lawsuit: the court orders the property sold (or, rarely, physically divided) and allocates the proceeds, with litigation over who paid what along the way. It is slow, public, and expensive — often costing a meaningful fraction of the equity being fought over.

The one-page alternative is deciding these questions in advance: a buyout formula, an appraisal mechanism, a deadline to refinance the mortgage out of the departing partner’s name, and a fallback sale procedure. Every one of those terms is enforceable under Morone — and every one of them is unavailable if it was never written down.

Because a cohabitation agreement is an ordinary contract, New York does not impose the strict execution formalities that govern prenups. But “not required” is not the standard we recommend. To give the agreement the best chance of surviving a challenge:

• Put it in writing and sign it. An express oral agreement is theoretically enforceable under Morone, but proving one is exactly the swearing contest the Court of Appeals warned about — and agreements that cannot be performed within a lifetime or that convey real estate interests run into the statute of frauds.
• Acknowledge it before a notary, the way a deed is acknowledged. It costs nothing and removes any later dispute about the signatures.
• Exchange honest financial disclosure. Agreements signed in the dark are the ones courts view with suspicion.
• Get independent review. When each partner has their own attorney — even briefly — claims of duress or overreaching lose almost all their force.
• Update it at life events. Buying a home, having a child, a big inheritance, or an engagement should each trigger a review.

If marriage is on the horizon, plan the handoff deliberately. A prenuptial agreement must satisfy DRL §236(B)(3) — written, subscribed, and acknowledged with deed-level formality — and it can resolve a question your cohabitation agreement cannot: how the years you lived together before the wedding are treated if the marriage later ends. Couples who built assets during a long premarital period often use a prenup to define those contributions on their own terms rather than leaving them to the default rules; see our guide to whether prenups are enforceable in New York.

New York gives unmarried couples a strange bargain: almost no rights by default, and almost unlimited freedom to create their own by contract. Most couples never make the choice consciously — they simply drift years deep into shared finances on the assumption that the law sees what they see. It does not. If you own a home together (or one of you is paying toward a home you don’t own), if one partner has stepped back from a career, or if children are in the picture, the conversation is worth having now, while you agree with each other. We help couples throughout Buffalo and Western New York put these agreements in place — and we represent partners untangling a separation where no agreement was ever made.