Cohabitation Agreements in New York: Protect Yourself Without Marrying

More couples than ever share homes, mortgages, businesses, and children without marrying. New York law has not caught up with them. There is no common-law marriage in New York, and when an unmarried couple separates, the default rules give the financially weaker partner almost nothing: no property division, no maintenance, no inheritance.

A cohabitation agreement replaces those harsh defaults with rules you choose. It is the single most effective legal protection available to unmarried couples in New York — and one of the least used.

Why New York Law Makes This Agreement Essential

In Morone v. Morone, 50 N.Y.2d 481 (1980), the New York Court of Appeals drew a bright line: courts will enforce an express agreement between unmarried partners — even an oral one — but will never imply an agreement from the couple's conduct, however marriage-like the relationship was.

That rule has two practical consequences. First, everything depends on what you can prove was actually promised. An oral promise is enforceable in theory and a nightmare to prove in practice: the case becomes one partner's memory against the other's. Second, a clear written agreement is close to bulletproof by comparison. You are not asking a court to reconstruct a decade of kitchen-table conversations; you are handing it a signed document.

What a Cohabitation Agreement Should Cover

The home. Who owns it, in what shares, and what happens on a breakup: buyout rights and pricing, a forced-sale mechanism, how mortgage payments and improvements are credited, and who may remain in occupancy (and for how long) while the buyout or sale plays out. If the home is titled in one name but both contribute, say exactly what the contributing partner earns — an ownership percentage, a reimbursement right, or nothing.

Money and expenses. Which accounts are joint and which are separate, how household expenses are split, and what happens to jointly held funds at separation. Remember that under Banking Law § 675 a joint account is presumptively a true joint tenancy — if an account is joint only for convenience, the agreement should say so.

Property acquired during the relationship. Furniture, vehicles, art, crypto, points and miles — and, critically, appreciation of each partner's separate assets. The agreement can keep everything separate, create sharing rules, or anything in between.

Businesses and careers. If one partner works in the other's business, or gives up income or relocation opportunities for the relationship, define what compensation or equity (if any) results. These are exactly the "I sacrificed for you" claims that Morone bars unless they were made express.

Support. New York implies no support duty between unmarried partners — but an express, written support promise (amount, duration, conditions) is a contract a court can enforce. Conversely, the agreement can confirm that neither partner will owe the other support.

Debts. Who is responsible for which liabilities, and indemnification if a creditor pursues the wrong partner.

Dispute resolution. Mediation-first clauses, attorney's-fee provisions, and choice of law.

What a Cohabitation Agreement Cannot Do

It cannot fix custody or child support in advance. Custody and parenting time are always decided by the court under the child's best interests as of the time of the dispute, and child support belongs to the child: any support terms must comply with the Child Support Standards Act, and courts are not bound by parental waivers. You can express intentions, but the court has the last word.

It cannot create marital rights. Signing a cohabitation agreement does not give either partner a spouse's inheritance rights, tax treatment, or governmental benefits. If you want your partner protected at your death, you need wills, beneficiary designations, and (where appropriate) joint titling — the agreement should be part of a coordinated plan.

It cannot be one-sided to the point of unconscionability. Like any contract, an agreement procured by fraud, duress, or overreaching is vulnerable. Full financial disclosure and separate counsel for each partner are not technically required — but they make the agreement far harder to attack.

The Formalities: Do It Right

Put it in writing, have both partners sign, and have the signatures acknowledged before a notary in recordable form. A signed writing avoids the Morone proof problem entirely; the acknowledgment removes "that's not my signature" disputes and matters for any real-estate terms.

The acknowledgment has a second benefit. If you later marry, New York gives full effect to agreements made before marriage only if they were written, subscribed, and acknowledged in the manner required to record a deed (Domestic Relations Law § 236(B)(3)). A properly acknowledged cohabitation agreement can be drafted to survive a later marriage and operate as a prenuptial agreement — an enormously valuable feature for couples who "might get married someday." If your agreement was informal and you have since married, a postnuptial agreement can cure the gap.

Cohabitation Agreement vs. Prenup vs. Postnup

All three are private contracts about property and support; the difference is timing and legal framework. A cohabitation agreement governs partners who are not marrying (or not yet); ordinary contract law controls. A prenuptial agreement is signed before a wedding and takes effect at marriage under DRL § 236(B)(3), controlling equitable distribution and maintenance at divorce or death. A postnuptial agreement does the same work after the wedding. Couples who move from cohabitation to engagement should upgrade their agreement — the economics of a marriage (maintenance rights, equitable distribution, elective share) are different in kind from those of cohabitation.

When to Sign One

The best time is before the big commitment: buying property together, one partner moving into the other's home, a partner leaving a job or relocating, merging finances, starting a business together, or having a child. The agreement is easiest to negotiate when the relationship is strong and the stakes are still theoretical.

Frequently Asked Questions

Are cohabitation agreements enforceable in New York?

Yes. Under Morone v. Morone, 50 N.Y.2d 481 (1980), express agreements between unmarried partners are enforceable under ordinary contract law. What New York courts will not do is imply an agreement from the relationship itself — which is precisely why the agreement should be express and in writing.

Does a cohabitation agreement need to be notarized in New York?

An ordinary contract needs only signatures, but we strongly recommend a notarized acknowledgment in recordable form. It defeats later signature disputes, supports any real-property terms, and — if drafted to survive marriage — lets the agreement satisfy the DRL § 236(B)(3) formalities that New York requires for agreements made before marriage to be given full effect in a divorce.

Can a cohabitation agreement decide custody or child support?

No. Custody and parenting time are decided under the child's best interests at the time of the dispute, and child support must comply with the Child Support Standards Act. An agreement can state the parents' intentions, but it cannot bind the court on either subject.

What happens to our cohabitation agreement if we get married?

It depends on how it was drafted. An agreement that was signed, and acknowledged in deed-recordable form, can be written to continue in effect as a prenuptial agreement under DRL § 236(B)(3). An informal agreement generally will not carry into the marriage — in that case, sign a prenup before the wedding or a postnup after it.

We never signed anything and we're separating. Do I have any rights?

You may. Express oral promises are enforceable if you can prove them; equity may impose a constructive trust on property your ex holds (Sharp v. Kosmalski, 40 N.Y.2d 119 (1976)); jointly titled real estate can be partitioned (RPAPL § 901); and joint accounts are presumptively joint (Banking Law § 675). See our full guide to unmarried partners' rights at breakup.

This article is attorney advertising and is provided for informational purposes only. It does not constitute legal advice, and reading it does not create an attorney-client relationship. Every case is different; consult a qualified New York matrimonial attorney about your specific situation.