You cannot get a prenup without marriage. A prenuptial agreement is defined as a contract made in contemplation of marriage and effective only upon marriage, so if you never walk down the aisle, the document never activates. The instrument built for unmarried couples who want the same kind of financial clarity is a cohabitation agreement, which works under ordinary contract law and takes effect as soon as both partners sign.
Why a Prenup Needs a Wedding
The rule comes from the Uniform Premarital and Marital Agreements Act, adopted in some form by roughly half the states, which describes a premarital agreement as one made “in contemplation of marriage and to be effective upon marriage.”1Uniform Law Commission. Uniform Premarital and Marital Agreements Act States that follow their own prenup statutes rather than the uniform act keep the same core requirement. You sign the document while single, which is what sometimes confuses people, but it sits dormant until a marriage license and ceremony bring it to life. No wedding, no enforceable prenup. A family court will not divide assets or set support based on it.
You cannot get around this by calling the document something else. Courts look at substance, not the label at the top of the page. A contract between two unmarried people that tries to mimic prenup protections gets treated as a cohabitation agreement regardless of what it’s titled, and it lives or dies under contract law rather than family law.
The Cohabitation Agreement: What Actually Works
A cohabitation agreement is a private contract between two people who live together, defining their financial rights and obligations toward each other. Because it is a contract like any other, it is governed by the same principles that apply to a business partnership or a real estate deal, not by family law. That distinction shapes everything from how disputes get resolved to which court hears them.
The legal foundation traces to a 1976 California Supreme Court decision recognizing express contracts between unmarried partners as enforceable, provided the agreement is not based solely on a sexual relationship. That principle has spread widely, and most states now recognize written cohabitation agreements as valid contracts, though enforcement standards vary. Written agreements are far easier to enforce than oral ones; several courts have refused to recognize implied or oral arrangements between unmarried partners for lack of proof. If you are going to the trouble of defining financial terms with your partner, put it in writing.
What a Cohabitation Agreement Can Cover
The core purpose is drawing clear lines around money and property. Before drafting, both partners should lay out a full picture of what they own and what they owe: bank balances, investment accounts, real estate values, vehicle titles, and outstanding debts. That disclosure protects both sides and gives a court a baseline if the agreement is ever challenged.
From there, the agreement can address:
- Separate property owned before the relationship, identified specifically by deed reference or account number so it does not get mixed in with shared finances.
- Joint purchases such as a home or vehicle, with ownership percentages spelled out. If one partner pays 70% of the mortgage, the agreement can grant them 70% of the equity on sale.
- How rent, utilities, insurance, groceries, and other recurring costs get split.
- Who carries which debts, and what happens to jointly incurred debt if the relationship ends.
- Who keeps the furniture, appliances, and other household belongings. This sounds trivial until you are arguing over it.
Specificity matters. Vague language like “we will split things fairly” gives a court nothing to enforce. The more precise the dollar amounts, percentages, and asset descriptions, the more likely the agreement survives a challenge.
What a Cohabitation Agreement Cannot Do
Child Custody and Support
No private contract between parents can permanently settle child custody, visitation, or support. Courts decide those questions based on the child’s best interests at the time of the dispute, not on what two adults agreed to years earlier. A cohabitation agreement can state preferences about custody, but a judge can override every word if the terms don’t serve the child. Child support waivers are even more problematic: a provision limiting or eliminating a parent’s support obligation is unenforceable because support belongs to the child, not the parents. Courts will ignore that clause.
Inheritance
A cohabitation agreement is not a will. In most states, unmarried partners have no inheritance rights under intestate succession laws. If your partner dies without a will, the estate passes to blood relatives, a legally married spouse, or adopted children. You inherit nothing by default, regardless of how long you lived together or what your cohabitation agreement says.
An agreement that spells out wishes about post-death asset distribution can support a surviving partner’s claim in probate court, but it cannot force the court’s hand the way a properly executed will can. Draft both documents and make sure they say the same thing. Name each other as beneficiaries on retirement accounts and life insurance policies as well, since those designations override wills and cohabitation agreements alike.
Medical Decisions
If your unmarried partner becomes incapacitated, you have no automatic right to make medical decisions or even access their records. Blood relatives typically get priority. Unmarried couples need separate documents beyond a cohabitation agreement: a healthcare proxy authorizing your partner to act on medical decisions, a living will outlining end-of-life wishes, and a HIPAA authorization form granting access to medical records. Without these, you could be shut out of the hospital room.
Federal Benefits No Contract Can Fix
A cohabitation agreement protects you from each other. It does nothing about the federal benefits reserved for married spouses, and no contract can change that.
The largest gap involves gift and estate taxes. Married spouses can transfer unlimited assets to each other without triggering gift tax through the marital deduction.2Office of the Law Revision Counsel. 26 USC 2523 – Gift to Spouse Unmarried partners do not qualify. Every transfer between unmarried partners above the annual gift tax exclusion of $19,000 per person in 2026 counts toward the lifetime exemption and could eventually trigger tax liability.3Internal Revenue Service. Whats New – Estate and Gift Tax That matters when one partner buys the other a car, pays off their student loans, or adds them to a property deed.
Social Security survivor benefits are another gap. A surviving spouse can collect on a deceased partner’s earnings record, but eligibility generally requires a legal marriage of at least nine months before the death.4Social Security Administration. Who Can Get Survivor Benefits An unmarried partner of 30 years gets nothing from Social Security no matter what the cohabitation agreement says. The SSA recognizes some valid non-marital legal relationships, but these are narrow exceptions that vary by state.
Unmarried couples also cannot file joint federal tax returns, cannot roll over a deceased partner’s IRA without tax consequences the way a spouse can, and typically cannot cover each other under employer health insurance plans. A cohabitation agreement should account for these disparities, for example by building in provisions for one partner to maintain their own retirement savings or life insurance to compensate for the missing spousal safety net.
Making the Agreement Hold Up
Cohabitation agreements do not legally require each partner to have their own attorney, but skipping that step is one of the fastest ways to get an agreement thrown out later. When both partners use the same lawyer, or when one has counsel and the other does not, courts are more receptive to arguments that the unrepresented party did not understand the document or felt pressured. Separate attorneys eliminate that argument almost entirely. A straightforward review typically runs a few hundred dollars per person and climbs higher when significant assets, business interests, or real property are involved.
Notarization is generally not required for validity but is strongly recommended. A notarized signature creates a formal record that both parties signed voluntarily and that their identities were verified, making it harder for either partner to later claim they never signed or were coerced. Notary fees typically run $2 to $25 per signature. Store the original in a fireproof safe or bank safe deposit box, and keep copies with both partners and their attorneys.
Revisit the document when life changes. An agreement drafted at 25 with a shared apartment and a car loan may not reflect your life at 40 with a house, investment accounts, and children. A new home purchase, a child, a significant income change, or a business launch all warrant an update. Some couples build in a formal review clause every five or ten years; others tie reviews to specific milestones. Either approach beats discovering your agreement is outdated during a breakup.
State-Specific Complications
Most states enforce written cohabitation agreements, but a small number create complications. A couple of states still have laws on the books prohibiting cohabitation itself, and courts there may refuse to enforce a contract built around an arrangement they consider unlawful. If you live in a state where cohabitation carries any legal cloud, talk to a local attorney before relying on a standard template.
A handful of states recognize common law marriage, which is a different wrinkle. If your state considers you legally married based on your conduct, living arrangement, and how you present yourselves to the community, you may actually have access to divorce court protections, and your cohabitation agreement may be treated more like a prenup. Requirements vary widely by state, including how long you must live together and what evidence of mutual intent is required. Confirm whether your relationship might already qualify as a legal marriage before deciding which document you need.
If You Later Marry
A cohabitation agreement stops working the moment you get married. Marriage triggers a different legal framework, and the cohabitation contract has no effect after the ceremony. If you want the same protections to carry forward, you need a prenuptial agreement covering the same terms.
If marriage is a possibility down the road, draft the cohabitation agreement with a prenup conversion in mind. Use parallel asset disclosures, similar division terms, and similar language so translating one into the other is a straightforward process rather than a ground-up rewrite. Ask your attorney during the cohabitation drafting what a future prenup would need to look like, and keep the two documents structurally close.